# Outside Air Kits, Do you recommend them?



## MountainStoveGuy

Recently, i have had lots of inquries about outside air kits, i know this has been discussed before, but i thought i would rekindle the discussion. Its my view, that they can be dangerous, expecially in a situation of a poor drafting chimney. I have had customers tell me that they have had smoke and sparks flying out the side of there house. Reverse draw presents a problem with the perfect "storm" exists. ie; super cold chimney, poor desingned chimney, windy conditions, and a new fire. I read sometime back in Hearth and Home that the industry was shying away from them, and the only reason they exist is so they dont miss the mobile home market, which the federal governmet required outside air kits on all stoves. So my questions to dealers and homeowners...  dealers, do you sell them and reccomend them? Homeowners, do you have one installed and what do you think it has done to improve performance? Do you think its a valid point that it makes a stove less efficient pulling freezing outside air and having to warm it to combustion temps?


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## begreen

This is a good question. We are really tightening up the old farmhouse this summer and I wonder if it's going to be an issue with our 3CB.

My understanding is that in a lot of modern, air-tight houses, there isn't enough combustion air for a robust fire. We've had posters on the forum that couldn't get their stoves working well until they cracked open a window. In that circumstance I would want an outside air supply. If there isn't enough oxygen for a robust fire, how much is left for people?


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## MountainStoveGuy

That is a situation that i havent realy come across, i  think that scenario is due to a combination of 2 things, to much negative pressure AND a tight house. My house is brand new. I built it myself over a two year span. I have 2x6 walls, blown cellulose insulation, tyvek on the inside and out. Good windows, good doors, etc. My house is tight. I dont have a outside air kit and i dont have any problems. I also dont have many fans exiting the house.  Only a bathroom fan, which gets very little use.


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## Shane

I agree that negative pressure is more likely a culprit than construction that is "too tight".  One thing I've thought of though is that colder air is more dense so wouldn't that be a good thing?


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## Corie

I always thought that too Shane.  As far as cars go, they operate most efficient when the intake air is coldest so one would think that a woodstove would operate in a similar fashion.  However, I've ALWAYS been told that was wrong, but without much explanation.

I guess the secondary part of the equation makes it a little more understandable, since ice cold air will cool the combustion air.


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## KP Matt

This always starts lively debates. Personally an outside air kit would be the very last thing I would do. If you need to crack a window doesn't that say more about your draft than your air supply?

Anectdotes abound, I'd like to see the numbers: how much oxygen does a stove require to maintain good combustion, how much air infiltration does a tight house allow, etc. If these houses were really that tight wouldn't you have strange phenomena like ears popping when you open/close the front door? Candles or oil lamps in the other room should noticeably brighten when the front door is opened.


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## MountainStoveGuy

Draft, tightness of a home, and negative pressure are all closely related. If you have stong draft, and its pulling hard, that alone creats negative pressure, add a exaust fan thats running, that creats more negative pressure, it the fan creates to much negative pressure it will nutralize the chimney, On the other hand, exaust fans create equalization points in the home when there not in use, wich is why i leave my bathroom doors open. As far as oxygen for combustion, i have no idea, but i can tell you it doesnt take much. The air is thin at my house. If your house didnt have a chimney, or any kind of exaust point except for the attic, i would guess that KPmatt's scinearo would happen.


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## Todd

My stove is in the basement and has to compete with the clothes dryer, water heater, and sometimes bathroom fan. I could notice a difference in the burning of my stove when they are all running. To compensate this effect I installed a Condar Air supply Ventilator near the stove and haven't had any problems since. I think it keeps positive pressure in my basement and helps the heat rise to the next floor. Maybe it's no better than an open window, but it's got a filter, and a flapper valve to control the amount of air that enters. Also think a little fresh air inside your home is good to have in the winter months.


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## HarryBack

my 2 cents:

I mostly sell pellet stoves, so my comments are thusly skewed. I like outside air. In a closed system. For instance, outside air, vented thru the sidewall, with the pellet stove vented out thru the sidewall as well....NOT the chimney. Most intakes should have a damper as well, hopefully negating backdrafts. Also, these days, most quality pellet stoves have vac switches that will eventually shut the stove down if it doesnt sense normal operating pressures. Tight homes are common around here, and when a customer calls complaining that their stove isnt throwing heat, the last thing they are going to beleive is that its THEIR home thats the issue...they figure that you are a shyster and are trying to find reasons why its their fault as to why the stove isnt heating well. Good Luck winning THAT argument. If theres an intake on the kit, that takes THAT variable out of the equation.


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## MountainStoveGuy

Taking that varible out of the equasion could potentially burn the customers house down in the case of a wood stove. As far as outside air to a pellet stove, i still believe that that dont run as efficient sucking in 10* air for cumbustion, there is no pre heat on a pellet stove, at least in the case of a wood stove the air gets pre heated, so by the time it gets it gets to the secondary burn chamber its hot, the argument there is that the cold air brings the over all temp of the stove down and doesnt get as complete combustion as it would if it was sucking 60* air. I hear you that customers dont want to hear that there house is broke, but sometimes, no alot of times thats the case, expecially in these modern tight homes with there commercial kitchens with overhead range hoods that suck 500cmf of air out of the house.


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## Roospike

This is my thought .... If your central gas heat system has to be installed with guidelines as per so much air per room size it is in , # of other units sucking the same air ,, bla . bla . bla .  Then you would think a wood stove , coal stove , pellet stove would have be the same.   ELK on isle 1 please , ELK ... Isle 1 . We need to get the Elk man in here in this subject .  When i installed a new fernace in our last house the area of the gas furnace had to have so much inlet air and had to be insuch a way .  Just something to think on . I was also told / or i read that if you use no inlet air supply then its draws air through any crack in the house it can find as per the stove has to cycle so much air an hour . On the other hand with a fresh air supply your homes hot air would be pushed out any cracks the house might have . In short the air cracks in the house are not going to go away but at lease its pushing hot air out on not cold air in .


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## Roospike

http://www.chimneysweeponline.com/hooa3.htm


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## Roospike

http://www.chimneysweeponline.com/hooa.htm


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## suematteva

Roospike thanks for that post best explanation that i have heard.


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## MountainStoveGuy

I dont think a web site is the definitive answer on this subject, expecially a web site that retails hearth products.  A outside air kit is a nice $100 add on in some cases. Most gas furnaces that require outside air are located in basements, where negative pressure is prevelant. Gas appliances that are getting reverse draw emit carbon monoxide,wood stoves emit carbon monoxide and smoke. You can at least smell the smoke and know you have a problem, on the other hand, when you get smoke coming out side of your outside air supply, you may or may not notice. It sounds like the web site hasnt had a problem with it, i tell you i have, only twice in ten years, but hey its happened. I havent heard any one speak up yet and tell me how much they love there outside air kit. If you do please post.  Im looking for personal experences here, weither you a hearth dealer or a consumer. Not web site links.


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## elkimmeg

To outside air or not to outside air that is the question Without loosing everbody after the first few sentences the answer is yes and no. First lets stick with wood stoves The formular to calculate the amount of combustion air from free flowing interior space is 1000 btu requires 50 cubic ft. IF competing appliances are in the same space like  clothes dryer 150 cfms removed, fuel fired hotwater heater furnace then wood stove all in a cellar  none are working effeciently  What can happen is one appliance can cause the adjacent one to backdraft. Air has to come from somewhere  the furnace can backdraft the hotwater heater or the dryer can backdraft the furnace  
 Backdraft is pulling co and co/2 into the living space.

 Deffinition of free flowing air space is a room or  rooms that air comunicates freely to make up the vollume. Doors to adjacent rooms.. those rooms can not be considered free flowing due to the door being able to be closed unless it is a louver door

Woodstove not in the cellar in a very tight home: In Canada outside air kits are not an option but required. 
 How effective are they? Well pressure nutralization has been mentioned.  The problem is the wind does not come from the same direction at all times. If one looks at what hapens when wind hit a home, it produced a positive pressure where it first makes contact.. For simplicity, the front of the home, as it hit the home, it is redirected all around the home up left right leaving a negative pressurization on the opposide of the home,where it first made contact. 

 Ok now you have the principle down where do you place the outside air feed? which side?  Remember wind does change directions 
An outside air feed on he negative side will draw air from your fire defeating its purpose. This theory was presented by Daneast or downeast a former member to this forum. It was his contention to  split the system and run feeds to opposite sides 

 Remember a woodstove is not an induced combustion, therefore a weaker draft system then burners or hotwater heaters.
 The location of outside air feeds for induced combustion is less of an issue. Air will be drawn in to those appliances. Really the outside air feed should be connected to the burned head of combustion chamber.

When there are competing appliances in close proximity,  it is best to feed the largest induced appliance first.

I purposely stayed away from quoting code but there are vollumes that address  these issues.  Again in the case of a wood stove with one outlet there can be a 50/50% chance the feed produces a negative effect. But when the house is so tight even one inlet might make a difference. 

I know I did not do the topic justice so as replys come in, maybe I can explain it better

 BTW spent the Day on Block Island.  Me and the wife had a real good time we biked atleast 25 miles. What a happening place

 while most were in the 90's we got to about 80 all the cooler ocean water around us  15 miles out in the sea.


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## KP Matt

I don't think Canadian code has required outside air kits since 1995.

http://www.wettinc.ca/WETTinkWinter2005.pdf



> The section has been completely rewritten to reflect a shift away from requirements for the supply of outdoor combustion air towards rules for managing house pressures or the consequences of smoke spillage.



WETT is a/the Canadian non-profit wood energy training and education association; as I understand it their pronouncements are based on the relevant national (Canadian) building code.

The idea is that outside air at best doesn't work, at worst can be dangerous, and the real solution is to design building systems better or make them more intelligent.


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## elkimmeg

I am familliar with Wett but thankls for the link and review.  USA and Canada codes are simmilar as both reconise EPA
 One builder in my area does install mechanical venting systems in basements. I have said many times this forum are  my educational 
 renewal. 

 Unfortunately they only addr5essed wood stoves in the 4 page link and did not really get into  outside air direct connections to other appliances


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## velvetfoot

I too am thinking of adding outside air, only to the oil burner heater (chimney) in the basement of my 3 year old house.  The kit that Burnham sells has a negative pressure relief damper that opens to the inside room air if the outside is blocked.  I am adding a radon fan in the basement, at some point, but they are the only two air consumers in the basement.  I did notice the kitty door in the basement wouldn't close in the winter because of the stack effect and I had to add some weight.  I also noticed that the air mixing damper (or whatever it's called) on the burner flue had a tendency to flap open even when the burner was off:  that's not supposed to do that, I don't think - perhaps it needs some adjustment.  Anyway, the prefab fireplace on the first floor had some kind of outside air arrangement.  It couldn't be turned off.  It was QUITE cool around the fireplace, which was remedied by blocking the inlet on the outside of the house.  The insert we got was not connected to use outside air;  the installer said they've never done that.

I am nervous about adding outside air to the oil burner...

I did add CO detectors on all levels.  They make combo units that I was able to retrofit to existing hardwired smoke detector system very easily.


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## Chuck Pearson

<<any one speak up yet and tell me how much they love there outside air kit.

I love the outside air kit on my wood burning fireplace insert.  I have had it since the fireplace was installed.  I would rather have the cold outside air cooling the fire than have the cold outside air cooling me as it is sucked through cracks in the house.  I like keeping the warm house air in the house instead of feeding the fire with it.  I like the smoke going up the chimney instead of being sucked into the house due to negative pressure.  Wind on the side of the house could create negative pressure but it would have to be very high negative pressure to overcome the draft of a good fire.  The laminar effect near the wall surface will reduce the negative pressure anyway.  My inlet is on the west side which is where winds come from most often.

I also love the outside air kits on my gas furnace and on my gas water heater.


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## Roospike

I would say that the only people that can answer this question(s) are the people that have actually used them . The pro's or the cons of how they work . Everybody else is just going off what they have heard or have read. ( my self included )  Based on common sence i can give my opinion like every one else. As Chuck Pearson has stated with his own experence , and what would make sence. The fresh air has to come from somewhere.


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## tradergordo

Vintage 181 said:
			
		

> Roospike thanks for that post best explanation that i have heard. (referring to chimneysweeponline link)



I thought so too at first (a while ago) after reading that site.  It made sense.  I was dead set on getting and installing an outside air kit.  There is one problem though - they are wrong.  This can be (and has been) tested scientifically.  The benefit of providing a supply of outdoor air to wood stoves is not supported by research results.

Please read The Outdoor Air Myth Exposed

Also note that even though chimneysweeponline was confronted with this report, and they even comment on it, they show a lack of understanding of the problem.  The issue is negative pressure - this is not caused by down winds (to your chimney) as chimneysweeponline seems to imply.  Nor can it be fixed with an anti-down drafting chimney cap.  Negative pressure forms when ANY sufficient wind at ANY time blows against the side of your house opposite the outside air connection.  We are NOT talking about wind blowing straight down your chimney (which is a problem that can be corrected with a better chimney cap).  The negative pressure formed near the outside air termination can cause air to come down your chimney through ANY opening regardless of the type of chimney cap you have.

Read the report I linked to above, it gives all the details.  In general, fireplaces that are vented by natural chimney draft should draw the air for combustion from the room in which they are located. Where necessary the indoor air pressure should be controlled to minimize depressurization.


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## velvetfoot

The Burnahm outside air kit has a backflow preventer damper which would close in the event it gets clogged or there is negative pressure, causing the burner to draw air from the room.

Page 36 of this document has a diagram:
http://www.burnham.com/pdfs/CurrentPDFfiles/8142824.pdf


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## MountainStoveGuy

Im a fan of the passive kits, like the condar asv-90. Good link tradergordo, thats exactly what was happening to my customers, The outside air was on the east side of the house with a marginal chimney. Wind blows here usually from west to east. The installed it against my recomendation and then had the guts to call me and tell me my stove i sold them was broken (Jotul Oslo).  There exact words "this stove shouldnt send smoke and sparkes out the side of my house, i want my money back". Thats exactly what they got, i didnt argue a bit, i explained the problem was the outside air kit, they didnt believe a word i said. I picked it up the next day to avoide getting into a lawsuit when there house burnt down.


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## tradergordo

Here's more from another reputable source (A Guide to Residential Wood Heating - written and distributed by a branch of the Canadian government):

*Does Outdoor Air Reduce Smoke Spillage?*
It has been widely believed that you could reduce or eliminate smoke spillage by supplying outdoor air through a duct, either directly to the appliance's combustion chamber or indirectly to the room in which the appliance is located. However, research shows that outdoor air supplies may not work. Smoke spillage occurs at the same level of room depressurization, whether or not an outdoor air duct is installed. The same research shows that wind effects around the house can reverse the flow in these ducts, which may create a fire hazard if the duct is connected directly to the combustion chamber.

Some building codes require that you provide wood-burning fireplaces with outdoor combustion air. You must comply with this requirement, but *be aware that performance will not improve*. And take steps to protect combustible materials around the duct from overheating if the gas flow reverses.


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## tradergordo

velvetfoot said:
			
		

> The Burnahm outside air kit has a backflow preventer damper which would close in the event it gets clogged or there is negative pressure, causing the burner to draw air from the room.
> 
> Page 36 of this document has a diagram:
> http://www.burnham.com/pdfs/CurrentPDFfiles/8142824.pdf



Looks like a good design - but now you need even MORE draft to overcome this mechanism (intake air now has to force open a louver).  This probably works well in an oil fired furnace/boiler because they use more intake air than a wood stove.  I'm not sure how well it would work with a woodstove, but I suppose in the worst case you would just be drawing air from the room all the time which would be about equivalent to not having the outside air kit at all.  Then again, perhaps the forces from negative pressure events could still weaken your draft even though air flow isn't running backward.


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## tradergordo

MountainStoveGuy said:
			
		

> Im a fan of the passive kits, like the condar asv-90. Good link tradergordo, thats exactly what was happening to my customers, The outside air was on the east side of the house with a marginal chimney. Wind blows here usually from west to east. The installed it against my recomendation and then had the guts to call me and tell me my stove i sold them was broken (Jotul Oslo).  There exact words "this stove shouldnt send smoke and sparkes out the side of my house, i want my money back". Thats exactly what they got, i didnt argue a bit, i explained the problem was the outside air kit, they didnt believe a word i said. I picked it up the next day to avoide getting into a lawsuit when there house burnt down.



Hah!  You should send them a copy of that report.  They probably bought another stove from someone else and had the same problem.  What a shame.  Yes, these outside air kits could be dangerous.

p.s.  The passive kits don't work either!


*Passive make-up air supplies*
A passive make-up type air supply is one that is not connected directly to the fireplace or stove combustion chamber. Since it is connected only to the house environment and not to the appliance, it flows air into a house only when the pressure inside is lower than the pressure outdoors, since air only flows to zones of lower pressure.  Passive air supplies don't make wood burners work better, they just make the house leakier.


Passive air inlets are nothing more than holes in the wall.  Wind effects may force air into the house or suck it out of the house, depending on the location of the hole relative to wind direction.


 Wind effects around the house also affect the direction and volume of flow through a passive inlet. If the weatherhood of a passive inlet is on the windward side of a building, wind pressure is likely to force air into the building; if the weatherhood is on the downwind side, the negative pressure zone created by the wind is likely to draw air out of the house, possibly depressurizing it. 
More importantly, it is misleading to think of the hole in the wall approach as supplying combustion air. In fact, passive air supplies provide air only in response to pressure differences. In cold weather, when temperature difference produces a pressure difference due to stack effect,  if a passive make-up air supply is located below the neutral pressure plane of the house (and there is no wind effect and no exhaust systems are operating), air will flow into the house. If, on the other hand, the passive inlet is located above the house neutral pressure plane, air will flow out.   

Passive air inlets do not supply combustion air, but flow air only in response to pressure differences.  Here, the flow direction depends on where in the house the passive hole is located.


It is useful to keep in mind a key physical principle: 
AIR FLOWS TO ZONES OF LOWER PRESSURE through any available opening.

The real problem with the passive make-up air strategy is that it does not reliably supply combustion air, nor does it reliably reduce combustion spillage. *Under favorable conditions it may tip the balance of driving and adverse pressures in favor of successful venting. This is why some fireplace specialists have reported performance improvements after the installation of a passive supply. However, it is also possible for a passive supply to cause spillage if air is drawn out of the house into a low pressure zone caused by wind effects. A remedial strategy that only works sometimes, and that may make the problem worse, is not a good strategy. A passive make-up air supply is really nothing more than another uncontrolled leak in the house envelope. A leaky house envelope is no guarantee of successful venting.*


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## velvetfoot

I think it could work.  Then again, we couldn't even tell HOW the outside air was routed to the old zero clearance fireplace, just that there was a short duct to somewhere in there.  It'd be nice to have a more engineered layout, similar to the oil burner example above, which who knows, might still be controversial in certain circles  .  As I said, the area around my fireplace got quite cold from the outside air.


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## Todd

tradergordo said:
			
		

> MountainStoveGuy said:
> 
> 
> 
> 
> Im a fan of the passive kits, like the condar asv-90. Good link tradergordo, thats exactly what was happening to my customers, The outside air was on the east side of the house with a marginal chimney. Wind blows here usually from west to east. The installed it against my recomendation and then had the guts to call me and tell me my stove i sold them was broken (Jotul Oslo).  There exact words "this stove shouldnt send smoke and sparkes out the side of my house, i want my money back". Thats exactly what they got, i didnt argue a bit, i explained the problem was the outside air kit, they didnt believe a word i said. I picked it up the next day to avoide getting into a lawsuit when there house burnt down.
> 
> 
> 
> 
> Hah!  You should send them a copy of that report.  They probably bought another stove from someone else and had the same problem.  What a shame.  Yes, these outside air kits are dangerous.
> 
> p.s.  The passive kits don't work either!
> 
> 
> *Passive make-up air supplies*
> A passive make-up type air supply is one that is not connected directly to the fireplace or stove combustion chamber. Since it is connected only to the house environment and not to the appliance, it flows air into a house only when the pressure inside is lower than the pressure outdoors, since air only flows to zones of lower pressure.  Passive air supplies don't make wood burners work better, they just make the house leakier.
> 
> 
> Passive air inlets are nothing more than holes in the wall.  Wind effects may force air into the house or suck it out of the house, depending on the location of the hole relative to wind direction.
> 
> 
> Wind effects around the house also affect the direction and volume of flow through a passive inlet. If the weatherhood of a passive inlet is on the windward side of a building, wind pressure is likely to force air into the building; if the weatherhood is on the downwind side, the negative pressure zone created by the wind is likely to draw air out of the house, possibly depressurizing it.
> More importantly, it is misleading to think of the hole in the wall approach as supplying combustion air. In fact, passive air supplies provide air only in response to pressure differences. In cold weather, when temperature difference produces a pressure difference due to stack effect,  if a passive make-up air supply is located below the neutral pressure plane of the house (and there is no wind effect and no exhaust systems are operating), air will flow into the house. If, on the other hand, the passive inlet is located above the house neutral pressure plane, air will flow out.
> 
> Passive air inlets do not supply combustion air, but flow air only in response to pressure differences.  Here, the flow direction depends on where in the house the passive hole is located.
> 
> 
> It is useful to keep in mind a key physical principle:
> AIR FLOWS TO ZONES OF LOWER PRESSURE through any available opening.
> 
> The real problem with the passive make-up air strategy is that it does not reliably supply combustion air, nor does it reliably reduce combustion spillage. *Under favorable conditions it may tip the balance of driving and adverse pressures in favor of successful venting. This is why some fireplace specialists have reported performance improvements after the installation of a passive supply. However, it is also possible for a passive supply to cause spillage if air is drawn out of the house into a low pressure zone caused by wind effects. A remedial strategy that only works sometimes, and that may make the problem worse, is not a good strategy. A passive make-up air supply is really nothing more than another uncontrolled leak in the house envelope. A leaky house envelope is no guarantee of successful venting.*
Click to expand...


My Condar ASV-90 seems to work for me. I have checked it out during windy days and it doesn't suck the air out of the house. My old stove use to smoke when I opened the door when the clothes dryer was running, after installing the make up air it didn't smoke any more. It does equal the pressure in the house, and I sapose it leaks cold air in too, but it's not enough to freeze me out of my house. I can leave the air ventilator wide open on a below zero day, and the stove still keeps the house at 80 degrees. Tight houses need something to equalize pressures and get some fresh air inside if not for combustion for health reasons also.


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## MountainStoveGuy

In the case of a customer that insists on outside air, sometimes a passive system is meeting in the middle. I agree, i dont think they work any better, but one thing for shure, they wont burn down the house.


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## elkimmeg

tradergordo: All research only test or mentions  the one outlet location. Go back and read my  response concerning multiple locations.
 Have you found any research the proves my theory wrong and what if one puts a  damper vlave to flow in the direction of highest pressure so  it is not a constant opening at all times. Code requires damper bafflets in bath exhaust fans?  same can be applied here but multi outlets or inlets This way one side actas for incoming pressues and one acts for out going pressure


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## KP Matt

This from a guy who claims:



> Regular wood stoves and fireplaces use room air for combustion and suck outside air in through every crack, which makes them virtually useless in subzero weather because they bring in cold air faster than they can heat the room.



Open fireplaces, generally true. Regular wood stoves, on the other hand, are certainly not virtually useless in subzero weather, regardless of how poorly insulated your house might be and whether you have an outside air kit. I don't think there's any money to follow over at woodheat.org as concerns their rejection of the value of outside air kits. Are they making money removing people's old outside air kits?


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## KP Matt

If a system was to malfunction in Washington state, sending smoke and sparks out the side of the house as described by MSG, most of the sparks would land in puddles and soggy moss. A banana slug might get singed.

I was a little too critical of the Ripples character; his blog has some interesting things on it. But I think he is a little naive in his acceptance of the outside air kit, if in fact it is not required by code in his location.

If I might ask, how much does an outside air kit cost? Installed?


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## MountainStoveGuy

So maybe this thread needs to point towards more hands on data, there are two schools of thought, both on oppisit ends of the spectrum. I have stated my real life experence dealing with ouside air kits. I stated in the first post that there needs to be a "perfect storm" for this to happen, a very high percentage of installs would be fine. I think its important to identify your install and see if its a canadate for outside air. To totally dismiss the danger aspect is ignorant, to say that outside air kits will always work is ignorant as well. There is a danger, i have seen it. But i have also seen plenty that work. So from a dealer standpoint, do i default to the no outside air kits theroy and protect my butt, or do i leave it to the average consumers hands to make there own decision? When we are talking fire burning appliances in peoples homes i tend to air on the side of caution.


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## Roospike

MountainStoveGuy said:
			
		

> So maybe this thread needs to point towards more hands on data, there are two schools of thought, both on oppisit ends of the spectrum. I have stated my real life experence dealing with ouside air kits. I stated in the first post that there needs to be a "perfect storm" for this to happen, a very high percentage of installs would be fine. I think its important to identify your install and see if its a canadate for outside air. To totally dismiss the danger aspect is ignorant, to say that outside air kits will always work is ignorant as well. There is a danger, i have seen it. But i have also seen plenty that work. So from a dealer standpoint, do i default to the no outside air kits theroy and protect my butt, or do i leave it to the average consumers hands to make there own decision? When we are talking fire burning appliances in peoples homes i tend to air on the side of caution.


 You would have one hell of a time selling cars , thats for sure...........HA ! Well MSG has a story about the out side air kit. There are other posters here with actual out side air kits that say they have had no probelms .  Anybody at all that has an actual out side air kit that has had a problem ?  The issue was bashed over last year on here and dont ever recall ANYBODY that had an issue that actually had the out side air unit.  Lots os storys tho . You would think if the out side air kits was such an issue #1 wood stove co wound not have them on ther stoves #2 The kits couldnt be sold #3 they wouldnt be CODE for moble homes & #4 They wouldnt be CODE for some states.  I also searched the net for storys of issues with these outside ait kits and didnt find any news storys nor could i find a court case about them . Just a bunch a bla , bla , bla . We have heard posters here DO that have outside air kits with no problem ...........Any body have one that DOES have a problem ? Anybody ?


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## tradergordo

Another informative study would be for everyone with an outside air kit to go inspect the insides and around the intake vent and look for some signs of soot (evidence of it running backwards).  Oh, and the danger from the thing running backwards isn't really because of sparks that might fly out and ignight something outside the house (although that is certainly a concern) - the danger I was thinking of was directly igniting the house.  Most outside air kits use super thin single wall piping to the outside.  Think about it this way - would you use the same material as a chimney going from your stove to your roof for example?   Perhaps it would take extreme conditions to actually set a house on fire this way, perhaps it has never happened (yet) but than again how long have these been in use?  It might take a decade or longer before any houses burn down.  

The one way valves seem like a good idea for safety although I don't know if the airflow is then restricted?  Notice that the passive kit mentioned here (condar) has an optional part you can purchase separately to restrict airflow to a single direction.

Elk - as for installing "x" number of holes in your house instead of just one... I don't know if that would really solve the problem?  It may help though.  Then again, if you are trying to avoid cold drafts which seems to be a big selling point for outside air kits, adding extra holes to different sides of your house probably isn't going to work for you.

I see both sides of the debate - like I said originally, I was at first dead set on buying an outside air kit...  but now I think its probably not going to have any benefit to me and in the worst case senario could be dangerous.  One thing I would like to do is actually get or borrow an air pressure meter and actually test my house to see if negative pressure is generated from the wood stove, and if so, how much?   I would also test while the gas clothes dryer was running, and maybe turn on all the vent fans (kitchen and bathrooms) just to see how much negative pressure I can even generate in my house.  Has anyone here done such a test?

I think the bottom line on this issue is that more research still needs to be done.


----------



## Roospike

tradergordo said:
			
		

> Another informative study would be for everyone with an outside air kit to go inspect the insides and around the intake vent and look for some signs of soot (evidence of it running backwards).  Oh, and the danger from the thing running backwards isn't really because of sparks that might fly out and ignight something outside the house (although that is certainly a concern) - the danger I was thinking of was directly igniting the house.  Most outside air kits use super thin single wall piping to the outside.  Think about it this way - would you use the same material as a chimney going from your stove to your roof for example?   Perhaps it would take extreme conditions to actually set a house on fire this way, perhaps it has never happened (yet) but than again how long have these been in use?  It might take a decade or longer before any houses burn down.
> 
> The one way valves seem like a good idea for safety although I don't know if the airflow is then restricted?  Notice that the passive kit mentioned here (condar) has an optional part you can purchase separately to restrict airflow to a single direction.
> 
> Elk - as for installing "x" number of holes in your house instead of just one... I don't know if that would really solve the problem?  It may help though.  Then again, if you are trying to avoid cold drafts which seems to be a big selling point for outside air kits, adding extra holes to different sides of your house probably isn't going to work for you.
> 
> I see both sides of the debate - like I said originally, I was at first dead set on buying an outside air kit...  but now I think its probably not going to have any benefit to me and in the worst case senario could be dangerous.  One thing I would like to do is actually get or borrow an air pressure meter and actually test my house to see if negative pressure is generated from the wood stove, and if so, how much?   I would also test while the gas clothes dryer was running, and maybe turn on all the vent fans (kitchen and bathrooms) just to see how much negative pressure I can even generate in my house.  Has anyone here done such a test?
> 
> I think the bottom line on this issue is that more research still needs to be done.


Please dont take this question(s) the wrong way. #1 Do you know how the out side air kit would be installed on your stove ? What brand stove ?  Unsure about other make and models , I can only speek for the Pacific Energy Summit stove.  The outside air kit IS hooked up to the stove BUT, its not a direct air hook up.  On the PE stove the outside air is hooked up to the back of the ash pan . The ash pan is where the air supply comes from to the stove , Its not an air tight system . I myself could not see how outside air kit could pull the air supply from the stove to change the draft . As stated , its hooked to the stove but not direct to the air supply.


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## Roospike

Copied a page of the PE Summit owners install guide. Shown in the picture where the air inlet supply can be installed . I would think if the air was pulled from outside (with outside air kit ) from a draft it would be more common to pull inside house air then to pull air from the fire or the chimney.


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## thechimneysweep

As the author of the website articles at http://www.chimneysweeponline.com/hooa.htm and http://www.chimneysweeponline.com/hooa3.htm , I thought I'd chime in here.  I visit the forum infrequently and just stumbled across this thread today, and have comments about several statements that have been made above.  In no particular order, here they are:

First, the one I'm a little steamed about.  Ours is a retail website, but that doesn't affect the facts or opinions we present in our Sweep's Library.  Most of those articles began as handouts we gave out to our chimney cleaning customers over 20 years ago, before we even had a retail store or internet website. These articles have been refined, expanded upon and corrected when necessary in the ensuing years, and we stand behind them. The insinuation made above that we promote outside combustion air because we profit from it is both unkind and untrue: aside from the fact that we happen to have more integrity than that, the parts we use to install an outside air intake to a Pacific Energy stove, for example, sell at any hardware store for about $15.00.

There is no need to wait for a decade of experience to determine the safety of direct outside air connection.  Direct OA connection to the firebox has been a legal requirement for all modular and manufactured homes throughout the US for over two decades, and there has never been a report of a hazardous situation of any kind that resulted from the outside air hookup (even in the unique super-wind-pressurization scenario described in another post above).  Further, ALL woodstove and fireplace installations in Washington State have required direct OA hookups for over a decade, with still not a single safety problem reported.  We're talking tens of thousands of installations, and not a single documented case of damage of any kind caused by an outside air system.

Hot air does burn more efficiently in a woodstove than cold air.  But the air introduced into the firebox by an outside air kit isn't necessarily cold: every woodstove we've ever seen that burns outside air has preheat chambers built into the sidewalls of the hot firebox through which the air must travel before it hits the fire.  We have witnessed hundreds of cases where outside air improved the burn, but never a single case where it impeded it, regardless of the outside  temperature.

By the way, these preheat chambers, along with baffling in the intake area and the industry-standard "airwash" design that introduces the combustion air into the firebox through a slot at the top of the viewing window, ensure that no burning material with enough density to cause a fire could  possibly be forced from the floor of the firebox, up the inside of the glass, through the airwash slot, downward through the preheat chambers, around the baffling, through the intake pipe and all the way to the outside of the house in any conceivable atmospheric condition.  MountainStoveGuy's statement that he has had customers report smoke and sparks "flying out of the side of their house" through their outside air intakes makes those customers the only reported witnesses to this phenomenon in history.  And if he relates this tale to Jotul's engineers, he is in for a lengthy explanation of why this would not be possible with today's stove designs.

There are many advantages to burning outside combustion air in a woodstove or fireplace.  It helps prevent exhaust intrusion into the room from the stove or fireplace (or other appliances in the home) due to room depressurization.  It helps prevent cross-drafting.  It ensures that the fire always has access to sufficient air for efficient combustion.  It prevents drafts in the room caused by cold outside air being drawn in due to house depressurization.  And these statements are not hearsay: I have personally witnessed the effectiveness of outside combustion air in hundreds of installations.


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## MountainStoveGuy

Why dont you explain why its impossible for smoke and sparks to come out of a modern stove? Im not here to prove anything to you, im hear to open up debate, you obviously think your findings are the gospel on this matter, but you can find otherweb sites that offer the oppisit views. This thread was not started to get links to websites. Yours included. I wanted first hand information from dealers and users. So when you say you have witnessed the effectivness of outside combustion in hundreds of installations, does this mean you tried them with and without air kits? sorry it miffed you that i mentioned that your a retailer, but hey, these things cost money and in this debate i dont think a link to a retailer that sells these things is a source. Like i said a few times in this thread, it would take a perfect storm for this to happen, and to think that my customer is the only one out there, is rediculious.(or maybe your suggesting that i made it up) There was a lengthy discussion of this topic and cases at the HPBA classes last spring.


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## elkimmeg

MSG I  am not defending tim the chimney sweep, but offering common sense to this situation before all is lost trying to win a debate.
 Lets start with some premises we all agree hot air rises and that cooler air is heavier?  Please explain how ahot a spark can travel threw a cooler air intake.  It suposed to be rising and the cooler outside air intake is located at the bottom of the stove? For some reason your  novice owners, did not grasp the dynamics of running a modern EPA stove,  they  concocked  stories,   that it was the stove or outside air to fault for the innability to opperate it correctly. IF you believe their wide eyeed embelishments, than  anything I say further is falling on death ears. You did the right thing by returning them the money and removing the stove. Did they provide any concrete evidence or just hearsay? I telling you what I say?,, from novices that did not know how to opperate a stove?

 The question is is outside air needed in a tight house? Any appliance needing combustion will take air from the path of least
  resistance. That includes inside air or outside air if available. That fact somehow was missed. Outside air is a supplement to inside air when combustion can not be  fullfilled by inside air. Don't believe me then why is the air inlet directed to indoor air? Why not have it  to regulate the outside air feed? The out side air feed is supplemental not primary.  2001 International Mechanical codes require provisions for an outside air feed into every fireplace. that's code required.  Why? research has indicated that having a super tight home is not all that Healthy.  IT like we errored  in one way so we have to make it up another way. 

 Plain and simple MSG you were manuplitated  and BS  you know it and that's why you started the thread.  You were placed in a no win situation and you made the right decision


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## Roospike

MountainStoveGuy said:
			
		

> Im not here to prove anything to you, im hear to open up debate, you obviously think your findings are the gospel on this matter, but you can find otherweb sites that offer the oppisit views. This thread was not started to get links to websites. Yours included. I wanted first hand information from dealers and users. So when you say you have witnessed the effectivness of outside combustion in hundreds of installations, does this mean you tried them with and without air kits? sorry it miffed you that i mentioned that your a retailer, but hey, these things cost money and in this debate i dont think a link to a retailer that sells these things is a source. Like i said a few times in this thread, it would take a perfect storm for this to happen, and to think that my customer is the only one out there, is rediculious.(or maybe your suggesting that i made it up) There was a lengthy discussion of this topic and cases at the HPBA classes last spring.


 Again , If this is the case ........ Then we have already had post of owners that have an outside air kit with reports of NO PROBLEMS , NO ISSUES .  Any post of owners that have had any issues ? no ? We didnt have any last time this topic came up , nor did we the time before.  Its a great topic but i think you are just grasping for straws now. I couldnt even come up with any news storys about outside air kit problems. Hey ! I have a friend that has seen a U.F.O. " sparks and smoke comming out the side of his house when it landed on his roof." Ok ......Its getting a bit silly .  BTW Good post thechimneysweep . Thanks for the attachment pic Coaster. Onward. The debate moves forth . Good points all .


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## velvetfoot

Well, I know the entire hearth area on my fireplace was darn cold when I had zero clearance fireplace (unused).  Does the typical Washington State design have any provision for dealing with this?  I remember the fellow from Alaska had outside air coming in to his stove!  There must be an optimum design.


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## thechimneysweep

MountainStoveGuy: 

I don't want to get into a pissing match with you, because I've read some of your posts and I have respect for your experience and opinions.  I spoke up here because I perceived an attack on my business ethics, and because I think you're very wrong on the subject of outside air.  I want to respond to three points in your latest post:

First point: I did explain why the flashback your customers described can't happen: reread paragraph 5 of my post above.  

Second point: I can't find "other web sites" that offer opposite views.  As far as I can determine, there is one: a Canadian guy named John Gulland who has a website named www.woodheat.org. I have long since given up debating outside air with this guy, who bases his opinion on the possibility of a backflash that can't possibly happen (see paragraph 5 again), along with a study done in 1989 that didn't even try to determine that outside air was a bad idea.

Third point: You say you were looking for viewpoints from dealers and users, and I am both.  I've been a hearth product retailer for 26 years, and have personally burned 62 different woodstoves.  On top of that, I've been a Chimney Sweep, an installer, a troubleshooter and dispenser of free advice for the same number of years.  The only ax I've got to grind is to get accurate  information out to people so they can make intelligent decisions about heating their homes.  If you don't want to listen to my opinion, who are you waiting to hear from?


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## MountainStoveGuy

No, no pissing matches here. Your points are as valid. It seems that i should start selling OAK's! . I have always been in the netural slot with this subject, some of the posts on here might not reflect that, i was trying to get some debate on both sides of the fence. I realize that most installs are safe, i have a hard time grasping the idea that its impossible to reverse draw through the stove. Thank you for your imput, you must realize the post in reguards to someone not quoting a retail website was not a intentional attack on you, And your opinion stated here by you was a very good post, It would seem this debate is over. I hope everyone got a good education, i did.


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## tradergordo

No need to get so heated or personal.  I think debate is good.  I know I've flip flopped back and forth a couple times already and maybe will again at some point.  To imply that someone is on one side of the fence to sell something, or that someone else got conned by a lying customer is just plain mean spirited (and not provable) so lets not go there.

If I have enough spare time, I would love to design a "myth busters" style test for this.  We could simulate wind with fans, and a house with maybe a scale size box/shed/aquarium?  Have to calculate normal draft in a chimney, and calculate what would be required to overcome that draft with pressure differences and exactly how hard a wind would have to be blowing, etc.  A separate issue to test is what can actually be expelled from an air intake in a modern stove.  This experiment is actually much simpler so maybe someone here can volunteer to do it (again if time permits I'll do it and make a digital video).  Just connect a fan up to the flue of a stove (blowing air INTO the stove) and see what you can blow through the firebox and out the air intake?  Maybe start with something simple first like the smoke of a match, and then move to something bigger like a handful of confetti/paper scraps.  But all this begs these questions - even if there are no big sparks - is it safe to have 1000 degree hot air blowing out these outside air kits?  And if it is safe, would it be safe if even tiny embers were included with that hot air blast?  And what materials are being used in the outside air connections?  And what would it take to melt those materials?  And why apparently are their no code specifications for these materials and how they are connected?


I do think the people who say its IMPOSSIBLE for these $15 outside air connections (are you using the standard thin flex aluminum tube and vents they sell at HD and Lowes typically for dryer vents?) to run backwards have more explaining to do.  Yes, hot air rises.  This force can be counter balanced by the fact that air is also pulled from high pressure to low pressure.  I do not believe it takes extraordinary conditions for this to happen (as implied by chimneysweep) but who really knows without scientific testing?  

I wouldn't be surprised if a stiff breeze on the side of the house opposite an outside air kit wouldn't be enough to overcome the natural draft of the stove and get the thing running backwards.  And I really do not think MSG's customer made up the story about his outside air connection running backwards but who are we to know?  For what its worth, I went to two stove shops while I was shopping for stoves, and of course asked them both about outside air kits.  The one store owner just plain told me it wasn't necessary (these modern wood stoves do not use that much air), the other told me he did not recommend them because they can run backwards.  That was actually the first time I had heard this, and was what started my investigation.  I didn't press for more information from this stove shop, but perhaps I should have.

I think the question is - if it only ran backwards on windy days (which might be one or two days out of the week) and even then, only for 20 or 30 seconds at a time - would it be a safety issue?  Probably not in reality.   Hence the lack of reported problems.  

These designs (images previously posted) that use the outside air connection as SUPPLEMENTAL are actually MORE disconcerting to me than a straight air-tight outside air connection.  There is much greater risk from the former of putting noxious fumes and possibly sparks into the actual living space (room the stove is located in) than if it was an air-tight outside air connection where downdrafts would just go outside.

As for healthier indoor air - this is/was probably the biggest concern I had.  After reading the chimneysweeponline article I was concerned that not using the outside air connection could leave me living in an oxygen deprived, negative pressure environment.  I see the arguments on both sides of this debate but I would think, ESPECIALLY in a tight house, you would actually end up with BETTER, not worse, indoor air quality when you DO NOT use an outside air connection.  Why?  Because without the connection, you are constantly REPLACING your indoor air with fresh outdoor air, this actually serves to remove stale air from your house and continually refresh it (this is also one argument for using a passive outside air device).  This of course assumes that your house isn't so tight that you depressurize it when running the stove.  Again, the only way to really know if you fall into this category is by testing.  As for efficiency - the cold outside air has to be warmed no matter which method you use (outside air connection cold air is warmed in the stove, cold air seeping in from cracks in the house is warmed outside the stove - both imply a loss of efficiency).


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## Todd

tradergordo said:
			
		

> As for healthier indoor air - this is/was probably the biggest concern I had.  After reading the chimneysweeponline article I was concerned that not using the outside air connection could leave me living in an oxygen deprived, negative pressure environment.  I see the arguments on both sides of this debate but I would think, ESPECIALLY in a tight house, you would actually end up with BETTER, not worse, indoor air quality when you DO NOT use an outside air connection.  Why?  Because without the connection, you are constantly REPLACING your indoor air with fresh outdoor air, this actually serves to remove stale air from your house and continually refresh it (this is also one argument for using a passive outside air device).  This of course assumes that your house isn't so tight that you depressurize it when running the stove.  Again, the only way to really know if you fall into this category is by testing.  As for efficiency - the cold outside air has to be warmed no matter which method you use (outside air connection cold air is warmed in the stove, cold air seeping in from cracks in the house is warmed outside the stove - both imply a loss of efficiency).



Me too. That is why I went with the air supply ventilator. It draws air to equalize the pressure and keeps a small amount of healthy fresh air circulating into the house.


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## thechimneysweep

tradergordo, I'm not the mean-spirited type, and wasn't attacking anyone personally.  It is pretty hard to respond to a specific point made in a specific post without referring to that poster, wouldn't you agree?  MountainStoveGuy has assuaged any rankled feelings I might have had in his gentlemanly post above, and there are no hard feelings.

I am, however, going to kick this horse just one more time, as you bring up some points that bear examination.

Your call for real world testing of the possiblility of OA flashback assumes that there has been no real-world testing, and that is not the case.

With tens of thousands of outside air kits installed in every conceivable weather pattern and wind condition in every area in this country for decades now, there has never been a documented case of outside air flashback.

That's tens of thousands of real world tests, every time the wind blows.  Including freak situations you could never hope to duplicate in laboratory testing.  For thirty years.  Zero flashbacks.

You are absolutely correct, lightweight, uninsulated aluminum dryer vent fittings are approved for outside air delivery to woodstoves and fireplaces.  We've been using it since the late 70's, and have no safety concerns with it.  Insurance companies have no problem with it, code authorities accept it, and stove and fireplace manufacturers almost universally offer the outside air option without fear of lawsuits.  The reason?  Tens of thousands of installations have proved that outside air flashback can't happen.

As to the passive nature of many outside air connections at the stove, this is just one of the built-in safeguards that ensure that outside air flashback won't happen.   It prevents the extreme suction from the firebox out the intake pipe that would be necessary to pull enough heat or embers through the system to cause a fire, by diluting it with room air.


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## begreen

Tom, FWIW I really appreciate your contributions to this discussion. It has been educational. I couldn't understand how stove manufacurers would provide stove modifications to allow outside air unless they were conviced that a) the market wanted this, b) there was a real, tangible benefit, and c) it was safe and reasonably liability free. After all, they have the most to lose.


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## MountainStoveGuy

The first thing i did today was call jotul and hearthstone. I havent talked to hearthstone, but i have talked to Jotul. Here is Jotuls position on the issue. Im quoting Mike in the tech department. "there potentially dangerous, there has been many documented cases involving house fires due to out side air kits backdrafting" "the scientific data done by the R&D department shows that there is little to no improvement on overall efficiency or performance" then i asked, then why do you sale them? There responce, "we as a manufacture are boxed in a corner, washington state required them and we dont want to miss market share"  "when dealers or customers call here, we absolutly do not recommend them"
I will keep you posted on hearthstones responce.
Ryan

Elk if you have time, can you call VC? or any VC dealer out there, can you get there opinion?


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## tradergordo

MSG - way to take the initiative in directly contacting the manufacturers!

Tom- this is DIRECTLY opposed to what you have stated.  Someone on one side of this debate is ill-informed.  Let's find out who!
Are there really "many documented cases involving house fires due to out side air kits backdrafting" as stated directly from the tech at Jotul?  How are we going to locate these documented cases?  Are they just urban ledgend?  Has the Canadian government also been duped somehow (their "residential guide to wood burning" document that I previously linked to in this thread says "The same research shows that wind effects around the house can reverse the flow in these ducts, which may create a fire hazard if the duct is connected directly to the combustion chamber").

And what about Jotul's comments that "the scientific data done by the R&D department shows that there is little to no improvement on overall efficiency or performance" which is also basically what is stated in the Canadian document.  

I think the Jotul guy had a great answer for why all the stoves have the OA adapters and kits - politicians basically FORCED them into it!  And in all fairness, I'm sure the politicians thought they were doing the right thing but at least if you believe these references to research and documented problems, it turns out to not be such a good idea.  

I know we are going to get to the bottom of this!




			
				MountainStoveGuy said:
			
		

> The first thing i did today was call jotul and hearthstone. I havent talked to hearthstone, but i have talked to Jotul. Here is Jotuls position on the issue. Im quoting Mike in the tech department. "there potentially dangerous, there has been many documented cases involving house fires due to out side air kits backdrafting" "the scientific data done by the R&D department shows that there is little to no improvement on overall efficiency or performance" then i asked, then why do you sale them? There responce, "we as a manufacture are boxed in a corner, washington state required them and we dont want to miss market share"  "when dealers or customers call here, we absolutly do not recommend them"
> I will keep you posted on hearthstones responce.
> Ryan
> 
> Elk if you have time, can you call VC? or any VC dealer out there, can you get there opinion?


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## MountainStoveGuy

I was directed to Mark Lewis, the head tech to talk about the cases that they have documented. He is on vacation untill next week.


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## MountainStoveGuy

Hearthstone called me back, The lead tech there stated this, "out side air kits have a resonably safe margin for operating properly, our stove design realy prevents and chance of that happening, BUT, our testing shows that there is no benifit in terms of performance to use outside air kits". Then the million dollar question, why do you manufacture them? statement "two reasons, the state of washington requires them, and in the rare case of a huge open fireplace competing for air, if used at the same time, can present a problem."


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## tradergordo

Coaster said:
			
		

> I know this might sound silly, but one of my concerns is that the outside air opening on the side of the house would be buried in snow.  My place is in the Michigan UP, and annual snowfall is around 20 feet or so.



Someone earlier in this thread linked to a manual for a boiler or furnace with a pretty high-tech outside air kit.  The instructions in that manual specifically state that you should locate the outside air termination 2 feet above the highest expected snowfall height. That might not be possible for some people.  Your concern also brings up another possible problem with outside air kits in general - unless there is a filter of some kind,  they will probably be sucking in snow every single time it snows and that H2O is going directly into your firebox.  Not sure what effect that might have on your burning, creosote formation, or the cast iron parts of the stove.


MSG - sounds like more of the same, only I'd like to know what the heck "reasonably safe" means?  Do YOU want "reasonably safe" or do you want "safe"???  At any rate, they seem in agreement that there is basically no benefit and they only sell it because politicians essentially forced them to.


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## MountainStoveGuy

Last but not least, I just got off the phone with quadrafire, The tech i spoke to (which i no personaly) stated that there has never been a case of backdrafting in one of there stoves, he also stated that there isnt realy a reason to install one unless there is extreme negative pressure issues in the home. He stated that the baffle system is what realy prevents the backdraft to happen. He also stated that they arent very effective because the outside air kits arent air tight, and test have shown that there is little benifit except to combat negative pressure. 

So now i want to stir the pot alittle more, my brain works in funny ways, and i try to corralate everything i have heard from the manufactures this morning. Jotul is the only company that i talked to that stated they have documented cases. That brings me to two conclusions. 1) the tech was wrong, (mike is good i doubt that) 2) Jotul is the only one of the three that made catalytic stoves.  Does this make sense? In a cat stove there isnt a baffle system with a buch of little holes that the heat and smoke has to travel through to get out. On a cat, there is very little resistance and i think it would be very possible. Now thats is my own conclusion, no one stated that. 

SO, i feel that its reasonably safe to sell a OAK to a customer that wants it for new construction and is buying a secondary burn stove. BUT, one thing that all three agree about is that they offer little to no benifit, and can actually be a detriment to the over all performace. 

The plot thickens. It would be intresting to see what other manufactures have to say on the issue.


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## MountainStoveGuy

Now that im so courious, i got to lookin under all the stoves.  They all seem to have the air hooked up to the cumbustion chamber, not through the ash pan. What caught my eye though, is that the some of the slots (like the mansfield, the 80K btu hearthstone beast) only has a .75" by 2" slot for combustion air. with that little hole, how much air can realy be leaving the house??


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## thechimneysweep

Hearthstone's outside air intake openings are at the bottom rear of the stove.  The outside air must travel through a passageway to the front of the stove, turn a corner, travel vertically through preheat chambers on both sides of the door and then enter the firebox through a narrow slot across the top of the viewing window.  There might be an air pump strong enough to pull burning material off the floor of the firebox and backwards through all that chambering, but wind depressurization isn't ever going to do it.

I'm amazed at the Jotul rep's response to MountainStoveGuy's inquiry.  Jotul markets their stoves in something like 14 countries: I find it hard to believe that they would incorporate an outside air design that allows backflashing, just to benefit from product sales in Washington State.  My guess is that, if Jotul really did have documented cases of backflashing, they have long since redesigned their intake system to eliminate the possibility.


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## MountainStoveGuy

Tom ,just to clarify, it wasnt the rep, it was the tech department. Do you think that cat stoves would have a easier time to backdraft? You can see, from my last posts from the manufactures that im trying to be fair and clear on there opinions, all three said basicly that there a waste of time, and can be counter productive. Im not trying to justify either way on this subject, that for the readers to decide.  Are we shure that the euro models are avalible with outside air kits? Some of euro stoves out there arent even avalible with outside air, (RAIS and SCAN). From what i can tell, Jotuls OAK intakes are very similar in design to the other stoves that i have on the floor.


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## KP Matt

So can stoves which have no provisions in their desisgn for an outside air kit be installed in Washington state? Or do you jury rig something, or just use a passive "hole in the wall"? I notice the Jotul 602 and 118 manuals make vague reference to outside air, but they don't seem to have any fixture or knock-out that would allow for the easy installation of an outside air kit. 

As I understand it previously more jurisdictions required outside air kits; stoves which haven't been re-designed since the era when many jurisdictions required outside air kits naturally will still incorporate outside air kits into their design - it doesn't cost anything since they already have it, plus they don't want to miss out on the 6,000,000 potential customers in Washington state. 

People who buy such a stove that has a knock-out or an optional outside air kit are going to say to themselves "surely if the manufacturer saw fit to make provision for an outside air kit then that must be the safest, healthiest and most efficient way to go; so sure, I'll take the outside air kit - heck it only costs $50 more!"

The real test is whether new stoves that have been designed and introduced since most jurisdictions did away with the outside air requirement still incorporate the new design - from a business point of view designing, testing, incorporating a new outside air feature might not be worth it given that all it does is give access to a market of 6,000,000. Completely different decision compared to retaining an existing outside air kit.


----------



## MountainStoveGuy

If its Jotul's stance that there indeed dangerous, im shure they already know about it. Which brings up a good point, were the the other companies, for liability sake, not giving me the whole story? i dont think thats the case. Also its possible that these cases came from cat stoves that they produce, like Tom has said more then once, and i agree with him, it would be real hard to make the hot gasses and solid particles like coal and ash, reverse through a baffle system like the seconday burn system has, Jotul is the only company that i questioned that made cat stoves. I think this has something to do with it.


----------



## Todd

MountainStoveGuy said:
			
		

> Jotul is the only company that i questioned that made cat stoves. I think this has something to do with it.



I think the earlier Hearthstones were cat stoves, and didn't Quadrafire make some also? Keep up the investigation, this is getting very interesting.


----------



## MountainStoveGuy

KP Matt said:
			
		

> So can stoves which have no provisions in their desisgn for an outside air kit be installed in Washington state? Or do you jury rig something, or just use a passive "hole in the wall"? I notice the Jotul 602 and 118 manuals make vague reference to outside air, but they don't seem to have any fixture or knock-out that would allow for the easy installation of an outside air kit.
> 
> As I understand it previously more jurisdictions required outside air kits; stoves which haven't been re-designed since the era when many jurisdictions required outside air kits naturally will still incorporate outside air kits into their design - it doesn't cost anything since they already have it, plus they don't want to miss out on the 6,000,000 potential customers in Washington state.
> 
> People who buy such a stove that has a knock-out or an optional outside air kit are going to say to themselves "surely if the manufacturer saw fit to make provision for an outside air kit then that must be the safest, healthiest and most efficient way to go; so sure, I'll take the outside air kit - heck it only costs $50 more!"
> 
> The real test is whether new stoves that have been designed and introduced since most jurisdictions did away with the outside air requirement still incorporate the new design - from a business point of view designing, testing, incorporating a new outside air feature might not be worth it given that all it does is give access to a market of 6,000,000. Completely different decision compared to retaining an existing outside air kit.




the 602,f118,f100 and 3cb, are not mobile home approved and do not have a outside air kit avalible for them.


----------



## thechimneysweep

To answer one poster above, we can't sell a stove or fireplace in Washington State unless it has provision for direct connection to outside combustion air.  This applies to all wood, gas and oil stoves, fireplaces, furnaces, water heaters, etc.  Basically, if it has a fire in it, it must burn outside air.

There are cases where direct connection to outside air isn't possible (like installing an insert in a fireplace in the middle of the house, with no exposure to an outside wall or crawlspace).  In these cases, we can apply for a variance from the code authority, who might allow a passive makeup air kit installed in the nearest outside wall.

On another point brought up above, it isn't the case that more jurisdictions required outside air at one time and then stopped requiring it.  Thirty or so years ago, OA wasn't required at all.  Then HUD began to require OA for stoves, fireplaces and furnaces installed in mobile and modular homes, which were of tighter construction than the stick-built homes of the day.  Washington State passed its requirement much later in the game, about ten years ago as I recall, in response to the tighter building practices of today.

Although not required, many woodstoves and manufactured fireplaces offered the outside air option even thirty years ago, including high-tech models from other countries like the Kent Tile Fire from New Zealand and the Stack Vista from Australia.  The reason is, providing a source of outside combustion air to the fire can solve many common problems woodburners might encounter.   Here are a few:

Difficulty starting a fire unless a door or window is open.

No difference in the burn when the draft control is turned from low to high.

The smell of gas or oil exhaust from the furnace or water heater in the house whenever the stove or fireplace is burned.

Cold drafts in the house whenever the stove or fireplace is burned.

Smoke pouring in from fireplace B whenever there's a fire in fireplace A.

Smoke leaking into the room through the stove's air intake opening whenever the Jenn-Aire, bathroom exhaust fan or clothes dryer is used.

We've retrofitted outside air many, many times over the years to solve problems like these, and it definitely works.  In fact, nowadays, here in Washington State where outside air is mandated for all new installations, we seldom hear complaints about these problems at all.

As to the decision to connect your stove to outside air or not (assuming you're not in a mobile home or in Washington State), I'd say if you're not experiencing any of the problems that derive from burning room air, including those that appear above, there's no reason to do it.  But if you are having a problem, please don't avoid the outside air solution because somebody told somebody they heard of instances of flashback.  Unless, it seems, you've got a Jotul.


----------



## MountainStoveGuy

Tom, i would be courious how you would adress the perfomance issues stated by all three manufactures that i called. 

Coaster, Jotul does not sell direct to the public, They as a manufacture rely on us dealers, to convey correct information to the consumer. Its the dealers responsibility to determine weither or not a air kit is needed. Thats why most dealers will tell you to avoide them, except the washington state dealers, where there required by law. And in Jotuls defense, they didnt say that there Jotuls were the problem, they were speaking on air kits in general, and stoves in general. Not once did they say that yes, jotuls should not be hooked up to outside air, nor did they say there was many cases of of back flash in our stoves. They worded it very carefully when they talked to me. The Jotul OAK system is just like the others, it terms of how it works and where it draws the air around. Jotul did mention that they absolutly do not recommed them, except in extreem cases of negative pressure, but i think that comment was made in the contex that there worthless on improving efficiency, not that there stove will burn your house down.


----------



## MountainStoveGuy

Ohh no, i agree, we as american's love to file suit. Its a good thing that its next to impossible to happen. Im not going to loose any sleep. And, just because a manufacture states that they know of cases where this has happend, they didnt state that it happened because of there stove. That doenst make them liable for anything. I will say once again that from what i have learned here from tom, looking first hand at all the stoves, and what manufactures have told me, that it is near impossible for a modern secondary burn stove to backflash.  Any one feel like commenting on the statements made by the manufactures off the topic of backflashing? I think we have that coverd now. EXCEPT, one point that never got adressed. Can a catalytic stove backflash? No complicated baffles in those types of stoves.

All the manufactures agree to some extent that there a waste of time, and virtually offer no benifits in terms of efficiency, and can actually negativly affect the installation due to not properly sealing the penetration, and the leaky hookups.


----------



## thechimneysweep

MSG, if you're referring to the tech support guys' statements that a direct connection to outside combustion air doesn't accomplish much, I would say you're talking to the wrong people.  Being a dealer, you're in a position to have received bad information from tech support personnel in the past, as I have more times than I want to count.  My bet is, if you talk to the design engineers who decided to incorporate the outside air option, they'd tell you the same thing I've been saying: outside combustion air is an invaluable tool to solve a myriad of problems a homeowner might experience with a woodstove.  I'll also bet that, assuming the techie that answers your call knows what he or she is doing, if you called back and described one of the problems I outlined in my last post, that same techie will recommend outside air as a solution.  How about a buck and a beer?

I didn't really mean to pick on Jotul, was reaching for a little levity there.  But it does seem odd that none of the manufacturers our company does business with has ever heard of a single incidence of outside air flashback, yet the Jotul guy claims to have heard of "several".  On the surface, it would seem that if Jotul is in the unique position of having experience with several incidents of flashback not shared by the rest of the industry, there's at least a strong possibility those incidents involved Jotul stoves.  

Actually, I think it is more likely that Mike the tech guy was just shooting from the hip with his statement, and can't cite any documented cases of flashback at all.  Since you've got his ear, why don't you call him back and ask for detailed info?

Whoops, just noticed you've asked twice now what I thought about cats vs non-cats and the likelihood of flashback.  I don't sell any catalytic models, but from what I've observed, the incoming combustion air goes through the same preheat chambering and airwash slot at the top of the door in cats as it does in non-cats.


----------



## MountainStoveGuy

The techs i talked to are the senior techs at hearthstone and quadrafire, typically they shoot me strait. The Jotul tech is not the senior man ( i will be calling him next week ) but sounded fairly confident in his statement. I think i need to clarify something. I think people install OAK's for one of two reasons, or mabey both. 1st, major negative pressure problem and they need to isolate the chimney, 2nd the customer precieves that this is a way to get more bang for there buck out of there wood. So to wrap this thread up, I think these statements are true. 

1)outside air kits on MODERN stoves are not dangerous, however, they need to be installed properly per the manufactures specs.
2)outside air can fix problems related to draft due to extreme negative pressure, but the typical installation wont require one.
3)outside air does nothing for the burn efficiency of the unit, its not a performance enhancing tool.


----------



## elkimmeg

Only the state of Washington expericiences flash back on outside air installations

All mobile home installations have outside air flash backs

 No goggle searches comes with any incidents of wood stove outside air flashback  incidents

Only Jotul reports this being an issue.

I talked to VC as you recomended and I mean head of productions. He could not recall one incident of outdoor air flash backs. Again he admits  VC supplies the OA for sales in the state of WA plus mobile homes And it was Canadian code till recently. Has anyone checked to see if OA is required in Europe.  What is their position on this issue. 

By the fact OA is required for mobile homes  OA must serve a purpose  though not needed in the larger  residential dwellings.

Why does the state of Wa require it? What do they know we should know?  Let the post roll on

 Some raised a real valid point  out door vents are required by code to be located 1' the average  snow fall dept. I have asked the state  what dept to base the location. 4 years later I have not received an answer. This is being hashed out now, because carbon monoxide issues on  Direct vent exhaust exits from basement location appliances. People have died from snow blockage of the exhaust vents. I also would imagine if fresh air feeds to these appliances get blocked there is a chance for improper combustion and improped exhaust This being so then it is not a streech that it also could cause back drafting. Naturally all direct vent furnaces are suposed to have and oxegen depletion sensor that shuts them down or sensors that shut them down when levels of  exhaust fumes reach dangerous levels, But we do not live in the ideal world  in the case of these deaths  the automatic sensors or shutoffs did not work. Here is another part of my final inspections tyennise ball works good in the 2.5" pvc vents. I stuff it in to cause automatic shutdown  I give the appliance up to an hour and a half to go in the shut down mode


----------



## MountainStoveGuy

Great post elk, thanks for checking. We have established pretty well that flashbacks arent likeley to happen, no need to argue weither its possible or not, its a moot point. not enough data to support it. 

I do beleive that are needed, in certain rare situations of extreem negative pressure. The common factor here is that all three said they do nothing for efficiency of the stove, and that there only purpose is to take the flue out of the house envelope where negative pressure exists. 

If washington is anything like my state, states make stupid decisions, and stupid laws, all the time. I would flip that question around, why is washington the only state that requires it? what does the other 49 states know that washington doenst?


----------



## begreen

thechimneysweep said:
			
		

> To answer one poster above, we can't sell a stove or fireplace in Washington State unless it has provision for direct connection to outside combustion air.  This applies to all wood, gas and oil stoves, fireplaces, furnaces, water heaters, etc.  Basically, if it has a fire in it, it must burn outside air.
> 
> There are cases where direct connection to outside air isn't possible (like installing an insert in a fireplace in the middle of the house, with no exposure to an outside wall or crawlspace).  In these cases, we can apply for a variance from the code authority, who might allow a passive makeup air kit installed in the nearest outside wall.



When I bought the 3CB, there was no discussion of outside air. And no warning of getting a variance for it. Is this code provision for all houses or just mobiles? Seems like a lame provision unless qualified for certain types of construction. My understanding is that a lot of 3CBs are sold in state. This is the first time I've heard of the provision. If it's posted online, would you be able to pass on the code section so I can read up on it? Thx.


----------



## thechimneysweep

The original intention of the Washington State Ventilation and Indoor AirQuality Code (VIAOC), Sections 402.2, 402.3, and 402.4 was to mandate outside combustion air for all combustion-containing appliances, including wood, gas and oil burners, that were to be installed in new construction.  The reason was to prevent the problems caused by negative pressurization in new, tightly-built homes, which would also have some combination of kitchen or bathroom exhaust fans, clothes dryers, range hoods, attic ventilators, etc. already vacuuming air out of the home.

Unfortunately, the eventual wording referred to "new installations" instead of "installations in newly built houses."  Because of this wording, the majority of the code jurisdictions in Washington State have chosen to interpret the law as requiring outside air for all newly installed combustion-containing appliances in any house, even old leaky homes that are in no danger of developing negative indoor pressurization.  Our service area spans four code authorities, and all four require a direct outside air feed for all new installations, even in older homes.

There are exceptions: the code authority in King County, I'm told, enforces the original intention of the law, and only requires outside air hookups to appliances installed in newly constructed  homes.


----------



## begreen

Thanks Tom. Great explanation and yes, I'm in King county. That explains why it wasn't an issue here in our old farmhouse. Thank goodness they had the common sense to interpret the original intent and not literal writing of the code.


----------



## elkimmeg

> I would flip that question around, why is washington the only state that requires it? what does the other 49 states know that washington doenst?


    The smart a-- answer is 49 other states voted for Richard Nixon  in 1972 before he got impeached 
 One state did not. who was right in this situation.. I think with Washington  it has to do with the smog alerts air quality thing There are studies where OA   improves combustion. Improved combustion reduces particle pollutants










> If it’s posted online, would you be able to pass on the code section so I can read up on it? Thx.



 Unless I  convert it to Adobe Acrobat I can scan it in and post  to my web space 2003 has an intire chapter  address in Combustion air. 

 Here is the best  description for requiring combustion air by code. I walk into your basement and start sizing it up there are other fuel burning appliances that  the free flowing interior space  has enough combustion air to support now you want to install a wood stove. that competes with the combustion air space. Well  the additional required combustion air has to come from some place
 The obvious option is a fresh outdoor air feed. 

Code language also has wording concerning real tight homes ans requiring OA  so mabe its not just the state of washington but  lax code enforcement in the other 49 states except one town in the easter part of MA Letme get back into this I have to convert over to
a windows cvomputer


----------



## Shane

It seems that interpretation is where things always get screwed up.  I run into many instances where someone interprets something.  The worst one recently is finding a chunk of Simpson Duravent pellet flex installed in an attic the other day.  (the new lighter stuff not the heavy older stuff) It was a matter of inches from combustible framing and was serving as an offset.  I told the guy that he couldn't do that.  He informed me that stove shop #1 told him that's the way to do it but didn't have the pipe, he then went to stove shop #2 who also told him he could do that and sold him the flex.  "The tag says 0 clearance to combustibles".  I shook my head and wrote up the inspection report condemming the stove.  Scary stuff if those stores really did give him that advice.


----------



## MountainStoveGuy

I participate in this forum to keep sharp. Expecially in the off season. I also require my employess to keep up here on company time. I dont want to be one of "those" dealers. Im very happy this thread created the intrest that it did. 1300 views is telling you that this is a foggy topic that people are intrested in. I can tell you i have learned alot myself.


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## elkimmeg

http://www.mass.gov/bbrs/780CMR_Ch3620.pdf

3610.6.4Air for combustion and ventilation:
Solid fuel-burning appliances shall be installed in a
location and manner to assure satisfactory
combustion of fuel, proper chimney draft and
maintenance of safe operating temperatures.
Combustion air may be obtained from interior
spaces when the interior space containing the
appliance has a volume, in cubic feet equal to one
twentieth
(1/20) of the output Btu rating of all
fuel-burning appliances in the space. When
buildings are so tight as to preclude adequate
infiltration, provisions shall be made to introduce
outside air for combustion and ventilation

2003   NFPA  211 

12.3 Air for Combustion and Ventilation.
12.3.1  Solid fuel-burning appliances shall be installed in a location and manner so as to provide ventilation and combustion air supply to allow proper combustion of fuel, chimney draft, and maintenance of safe temperatures.
12.3.2  Where buildings are so tight that normal infiltration does not provide the necessary air, outside air shall be introduc


----------



## BrotherBart

Thanks for the post Elk. I now know I don't need outside air. You could fling a cat through any one of the air leaks in this place.


----------



## elkimmeg

BB I'm sitting on the fence on this issue. One question asked was why do stove manufactures  provide optional outside air kit provisions?. Many said it was to open their markets to the state of Wa.  There is another answer to be code compliant in tight homes, and stoves installed in areas with insufficient combustion air.   Which also explains why OA is required in mobile homes there is not enough air vollume to support proper combustion. Plus not all rooms qualify to supply combustion air Bath rooms  do not qualify. If I dig deep enough in the fire codes, I sure there is language that rules out bedrooms. Even common sense tells one not to oxygen deplete bedrooms.


----------



## Roospike

elkimmeg said:
			
		

> BB I'm sitting on the fence on this issue. One question asked was why do stove manufactures  provide optional outside air kit provisions?. Many said it was to open their markets to the state of Wa.  There is another answer to be code compliant in tight homes, and stoves installed in areas with insufficient combustion air.   Which also explains why OA is required in mobile homes there is not enough air vollume to support proper combustion. Plus not all rooms qualify to supply combustion air Bath rooms  do not qualify. If I dig deep enough in the fire codes, I sure there is language that rules out bedrooms. Even common sense tells one not to oxygen deplete bedrooms.


 I know it states that most gas heaters are not to be used in bedrooms , lack of oxygen . I was going to call Pacific Energy about the Outside air issues but just never got around to it yet , maybe Monday . I did ask about the outside air kits from my local dealer when i bought my stove last october , but got a deer in the headlight look from them, like i did with most of my questions that were not "standard questions".


----------



## begreen

I've been looking at many stove manuals today for clearances to combustibles. While in there, I looked into outside air information. Jotul had the most complete explanation. Here is what they have for the Oslo:

Outside air may be required if:
1. The Jøtul F 500 does not “draw” steadily, smoke rollout occurs,
fuel burns poorly, or back-drafts occur whether or not there
is combustion present.
2. Existing fuel-fired equipment in the house, such as fireplaces
or other heating appliances, smell, do not operate properly,
suffer smoke roll - out when opened, or back-draft whether
or not there is combustion present.
3. Opening a window slightly on a calm (windless) day alleviates
any of the above symptoms.
4. The house is equipped with a well-sealed vapor barrier and
tight fitting windows and/or has any powered devices that
exhaust house air.
5. There is excessive condensation on the windows in the
winter.
6. A ventilation system is installed in the house.

If these or other indications suggest that infiltration air is
inadequate, additional combustion air should be provided from
the outdoors.


----------



## Roospike

BeGreen said:
			
		

> I've been looking at many stove manuals today for clearances to combustibles. While in there, I looked into outside air information. Jotul had the most complete explanation. Here is what they have for the Oslo:
> 
> Outside air may be required if:
> 1. The Jøtul F 500 does not “draw” steadily, smoke rollout occurs,
> fuel burns poorly, or back-drafts occur whether or not there
> is combustion present.
> 2. Existing fuel-fired equipment in the house, such as fireplaces
> or other heating appliances, smell, do not operate properly,
> suffer smoke roll - out when opened, or back-draft whether
> or not there is combustion present.
> 3. Opening a window slightly on a calm (windless) day alleviates
> any of the above symptoms.
> 4. The house is equipped with a well-sealed vapor barrier and
> tight fitting windows and/or has any powered devices that
> exhaust house air.
> 5. There is excessive condensation on the windows in the
> winter.
> 6. A ventilation system is installed in the house.
> 
> If these or other indications suggest that infiltration air is
> inadequate, additional combustion air should be provided from
> the outdoors.


 Makes sence .  How many time has one heard to "open a window" for better draft . Not that i have to but have heard it many times over the years . mostly to get the fire rolling/started. good input B.G.


----------



## suematteva

elkimmeg said:
			
		

> BB I'm sitting on the fence on this issue. One question asked was why do stove manufactures  provide optional outside air kit provisions?. Many said it was to open their markets to the state of Wa.  There is another answer to be code compliant in tight homes, and stoves installed in areas with insufficient combustion air.   Which also explains why OA is required in mobile homes there is not enough air vollume to support proper combustion. Plus not all rooms qualify to supply combustion air Bath rooms  do not qualify. If I dig deep enough in the fire codes, I sure there is language that rules out bedrooms. Even common sense tells one not to oxygen deplete bedrooms.



Elk or Others,

Does it say anything about OA and basement installations?  A snorkel type setup was not recommended.

I spoke with two people from Hearthstone about OAK and am not sold on adding the thing on..Fully described the stove location and the type of burning, quality of wood and size, running temps of the stove, cresote level and house age, usual wind direction.  Age of house...This debate is very install specific.

My friend with a Jotul, basement install. Swears by it.  He burned two years with out it.  Added on loves it.  When cold 10 f the intake pipe will have rime ice for two ft in..I would have to say it it really pulling air.  

When manufacturers test stoves for burning performance in a lab how do they do it?.Is an outside type air kit used..Every home is obviously different yet they would have to use average home scenario.


----------



## scfa99

Just re-read my Quadrafire 7100 manual.

Page 21, warning box "IMPORTANT! outside air knob on front of fireplace must be in the open to operate firepace properly".

"Outside air is required to minimize the effects of negative pressure within the structure."

Page 9, "outside air is required for combustion".

So as a consumer, these statements imply that i HAVE to use it.  very confusing.


----------



## MountainStoveGuy

Thata correct, you have to hook some built in fireplaces to outside air. Since its a sealed front unit and its built in the wall that makes sense. You absolutly HAVE to use it. That unit has a second combustion air port designed to pull combustion air from another part of the house to help circulate inside air.


----------



## elkimmeg

Elk or Others,

Does it say anything about OA and basement installations?  A snorkel type setup was not recommended.

I spoke with two people from Hearthstone about OAK and am not sold on adding the thing on..Fully described the stove location and the type of burning, quality of wood and size, running temps of the stove, cresote level and house age, usual wind direction.  Age of house...This debate is very install specific.

My friend with a Jotul, basement install. Swears by it.  He burned two years with out it.  Added on loves it.  When cold 10 f the intake pipe will have rime ice for two ft in..I would have to say it it really pulling air.  

When manufacturers test stoves for burning performance in a lab how do they do it?.Is an outside type air kit used..Every home is obviously different yet they would have to use average home scenario.[/quote]

 Snorkel  code calls fro an exit location 1' above average snow fall But nobody can tell what the average dept of snowfall in in all locations.  Many are snorkeling the inlets and outlets locations to raise them to add extra margine of safety. There are issues, that add to the total length of the run and additional resistance or friction.

 Your friend has a differnt location different stove  and should insulate that  air supply if he is getting ice in there

 I know all the  EPA test results I have reviewed  they are in open areas.  I supose to spec them they have to test them.


----------



## suematteva

elkimmeg said:
			
		

> Elk or Others,
> 
> Does it say anything about OA and basement installations?  A snorkel type setup was not recommended.
> 
> I spoke with two people from Hearthstone about OAK and am not sold on adding the thing on..Fully described the stove location and the type of burning, quality of wood and size, running temps of the stove, cresote level and house age, usual wind direction.  Age of house...This debate is very install specific.
> 
> My friend with a Jotul, basement install. Swears by it.  He burned two years with out it.  Added on loves it.  When cold 10 f the intake pipe will have rime ice for two ft in..I would have to say it it really pulling air.
> 
> When manufacturers test stoves for burning performance in a lab how do they do it?.Is an outside type air kit used..Every home is obviously different yet they would have to use average home scenario.



 Snorkel  code calls fro an exit location 1' above average snow fall But nobody can tell what the average dept of snowfall in in all locations.  Many are snorkeling the inlets and outlets locations to raise them to add extra margine of safety. There are issues, that add to the total length of the run and additional resistance or friction.

 Your friend has a differnt location different stove  and should insulate that  air supply if he is getting ice in there

 I know all the  EPA test results I have reviewed  they are in open areas.  I supose to spec them they have to test them.[/quote]

Thanks Elk.

When I referred to "snorkel"  meant more a basement installation.  Snorkel (my analogy) meaning pulling the air from up above the foundation wall...Understand about the min 1 ft above average snowfall....In an above thread i think the term was low oxygne area (or something like it)..Would this include a basement..trying to understand why they do not recommend OAK in basement. thanks matt..am going to get my stove manual..


----------



## velvetfoot

I just read that for one particular burnham boiler cold air can result in flue temps that might be below condensation point causing possible corrosion.  (This is research for my possible purchase of an OAK for my oil burner).

Wouldn't cold air be denser and result in better combustion?


----------



## elkimmeg

There is language that allows   adding the basment location for combustion make up air  Most basements have competing appliances and it is not good to interupt what is already working.  The definition of outside air id air taken beyond the exterior of the home.. I think  it best to continue additional air to the outside,  a sealed passage can travel threw the basement.  Colder air also contains more oxygen and is better for combustion.  It is also denser and  more is available for combustion. IF an insert is spected for only outside air and placed in a firebox  Then it is not going to work  Particularly if there are no provisions for  room air to enter the combustion chamber. This debate can go on and on but all agree there are circumstances where outside air is the only solution.


----------



## tradergordo

"When buildings are so tight as to preclude adequate infiltration, provisions shall be made to introduce outside air for combustion and ventilation"

So does this rule out direct connection outside air kits (because they do not provide ventilation which appears to be a requirement of this code)?

"Even common sense tells one not to oxygen deplete bedrooms"

The assumption (and I've seen it several times now from OA proponents) seems to be that a stove using room air depletes the room of oxygen.  Based on what I've read, this is rarely the case (which is probably another reason why all the stove manufacturers techs have been saying the OAK's are unnecessary).  Only in the event that a stove depressurizes the room would you have oxygen depletion - in all other cases, you would actually be INCREASING oxygen levels in a bedroom (or any room with people in it) by using room air for your stove.  Why?  Because the stove draws in fresh air and exhausts stale air (air you've already depleted of oxygen by breathing it in then out).

I think a lot of people assume that modern high efficiency air tight wood stoves use a lot of air like an open fireplace.  The code you quoted seems to assume the same use of air per BTU from every appliance - not sure that is a reasonable assumption:

"Combustion air may be obtained from interior spaces when the interior space containing the 
appliance has a volume, in cubic feet equal to one twentieth (1/20) of the output Btu rating of all 
fuel-burning appliances in the space."

Also not sure what "in the space" means, in the same room?
So if my math is right, you can only use room air with a 50,000 BTU stove when it is in a "space" equivalent to 17.7 feet x 17.7 feet x 8 foot ceiling (and no other fuel burning appliance is in the same "space").

"When buildings are so tight as to preclude adequate infiltration, provisions shall be made to introduce outside air for combustion and ventilation "

How do you measure infiltration for adequacy?  Do you actually run the appliance while observing an air pressure meter or is it just based on the equation above?





			
				elkimmeg said:
			
		

> http://www.mass.gov/bbrs/780CMR_Ch3620.pdf
> 
> 3610.6.4Air for combustion and ventilation:
> Solid fuel-burning appliances shall be installed in a
> location and manner to assure satisfactory
> combustion of fuel, proper chimney draft and
> maintenance of safe operating temperatures.
> Combustion air may be obtained from interior
> spaces when the interior space containing the
> appliance has a volume, in cubic feet equal to one
> twentieth
> (1/20) of the output Btu rating of all
> fuel-burning appliances in the space. When
> buildings are so tight as to preclude adequate
> infiltration, provisions shall be made to introduce
> outside air for combustion and ventilation
> 
> 2003   NFPA  211
> 
> 12.3 Air for Combustion and Ventilation.
> 12.3.1  Solid fuel-burning appliances shall be installed in a location and manner so as to provide ventilation and combustion air supply to allow proper combustion of fuel, chimney draft, and maintenance of safe temperatures.
> 12.3.2  Where buildings are so tight that normal infiltration does not provide the necessary air, outside air shall be introduc


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## elkimmeg

Alll good valid questions I'm on myMac now but I willl supply the actual description of open air space  the short version id  any ajoining rooms that do not have a door that can be closed or it adequate sized grills are space  in the walls so that air can communicate between rooms Louver doors allow air thansmission as well Forget the 1/20  code also establishes for every 1000 BTU of an appliance output 50 cubic ft of free air is needed to support proper combustion. This becomes a huge problem, when people finish off basements.  and partition off the burner and hot water heaters in small confined spaces. 

If what you say is true then please educate all about the oxygen  Ventless gass heaters  have oxygen depletion sensors that shut down the  units when the oxygen levels  drop to approaching unsafe levels.. I have wittnessed then shut down with test equipment measuring the oxygen levels..  

There are companies that test green homes  that presurize homes and measure infiltration or escaping  If anyone is interested I will try to post a copy of how it is done and the testing results.  This one builder certifies his homes to be energy star compliant. 

 Condensttion of cold air by burnham I doubt that Cold dry air has less moisture so what's to condensate? If they were bringin warm moist air in a cool envoirment I can see how that could condensate but not the opposite way around. There is another way to bring in outside air called air in a can that is not directly connected to the burner head or combustion chamber 

later tonight I will cut and paste the acctual code about open space when I'm on my laptop. This is a good discussion

You did not click on the link at the top of the codes it is the entire chapter concerning combustion air

http://www.mass.gov/bbrs/780CMR_Ch3620.pdf


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## tradergordo

thechimneysweep said:
			
		

> ..."it isn't the case that more jurisdictions required outside air at one time and then stopped requiring it.  Thirty or so years ago, OA wasn't required at all.  Then HUD began to require OA for stoves, fireplaces and furnaces installed in mobile and modular homes, which were of tighter construction than the stick-built homes of the day.  Washington State passed its requirement much later in the game, about ten years ago as I recall, in response to the tighter building practices of today."



From Outdoor combustion air in the Canadian national building code

*Made mandatory in 1990, removed entirely in 1995*
The 1990 National Building Code (NBC) of Canada had mandatory requirements for outdoor air supplies for fireplaces, but, when the findings of Canada Mortgage and Housing Corporation (CMHC) research on outdoor air supplies were tabled during the revision cycle leading to the 1995 edition, the requirements were removed.  

Here is some background on the evolution of outdoor air supplies in the NBC. 

The 1990 NBC contained the following Article (clause): "9.22.1.4 Combustion Air.  Fireplaces, including factory-built fireplaces, shall have a supply of combustion air. (See Appendix A)" 

Appendix A-9.22.1.4. read in part: "The intent of this Article is to allow the fireplace to be operated without affecting, or being affected by, other appliances or exhaust equipment.  For this to occur, the fireplace must be provided with a supply of combustion air dedicated to the fireplace only; an opening to the exterior should be provided at or near the fireplace opening." 

The Article went on to require outdoor air for factory-built fireplaces in accordance with the manufacturer's instructions and gave a series of prescriptive requirements for outdoor air supplies for site-built masonry fireplaces. 

In the proposed revisions sent out for public comment in August 1993, it was proposed to delete Appendix note A-9.22.1.4. with the following reason given: "Combustion air supplies as currently prescribed are generally ineffective.  The requirement to provide combustion air is being deleted from CAN/CSA A-405, Design and Construction of Masonry Chimneys and Fireplaces and from the Code." 

The '95 NBC contains the following: "9.22.1.4. Combustion Air.   Where a supply of combustion air is provided directly to the fire chamber of a fireplace, including a factory-built fireplace, the installation shall comply with the "Outdoor Air Supply" requirements provided by CAN/CSA A-405, Design and Construction of Masonry Chimneys and Fireplaces."  This is the only reference to combustion air for fireplaces. 

The supply of outdoor air was made non-mandatory and this wording was included because the CMHC research that showed outdoor air supplies to be ineffective, also showed that direct-to-combustion chamber supplies could be hazardous because of the potential for wind-induced reverse flow of combustion gases through the supply duct.  The A-405 requirements proposed ways to provide outdoor air safely if you choose to supply it. 

Like most building codes in North America, the NBC included outdoor combustion air requirements for combustion equipment on the assumption that it was a good strategy to reduce spillage susceptibility.  Unfortunately the assumption was acted upon before any research had been done to explore how outdoor air supplies actually behave. 

The research reports that influenced the Standing Committee of Part 9 of the NBC are: 

1) Fireplace Air Requirements, ORTECH for Canada Mortgage and Housing Corporation, 1989 

2) The Effects of Glass Doors on Masonry Fireplace Spillage and Surface Temperatures, Virginia Polytechnic Institute for Canada Mortgage and Housing Corporation, 1994 

Copies of these reports are available from the CMHC information centre at (613) 748-2367.  

Although the two studies were conducted by two labs with different set-ups, different protocols and different appliance types (1. factory-built, 2. masonry), they arrived at the same conclusion: The susceptibility to combustion spillage due to room depressurization is not affected in a predictable way by the presence or absence of air supplied from outdoors, whether supplied to the combustion chamber or indirectly through a supply duct terminating near the fireplace. 

In both studies the reference room depressurization at which spillage was induced was 10 Pa.  In 'Fireplace Air Requirements', none of the five tested fireplaces spilled at 5 Pa depressurization despite the fact that all were very different in their configurations and features, although all did have glass doors.  The tests at the two depressurization levels were done with and without outdoor combustion air supplies. 

Once the research findings were in and analyzed, the underlying physical process became clear:  That is, air flows to a zone of lower pressure through any available opening, regardless of our wishful thinking.  In retrospect, this principle appears rather obvious, although for most of us it was not until revealed in the lab. 
...


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## tradergordo

elkimmeg said:
			
		

> If what you say is true then please educate all about the oxygen  Ventless gass heaters  have oxygen depletion sensors that shut down the  units when the oxygen levels  drop to approaching unsafe levels.. I have wittnessed then shut down with test equipment measuring the oxygen levels..



You are forgetting that an airtight wood stove drafts.  The draft is a critical component of the system.  In fact I would argue that most draft problems are the result of improper installation (and not due to using room air).  In my opinion it would be better to fix a bad installation rather than just slapping on an outside air kit.  The draft of the stove is what pulls fresh air into the house as stale air is exhausted from the house.  A ventless gass heater obviously cannot do this.  So yes, ventless devices, even candles, can deplete a room of oxygen.




			
				elkimmeg said:
			
		

> There are companies that test green homes  that presurize homes and measure infiltration or escaping  If anyone is interested I will try to post a copy of how it is done and the testing results.



I'm interested.


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## elkimmeg

I think Canada has a colder climate than most of USA. Colder air has different oxygen and density levels at colder temp Testing for atmosphere conditions in mid Ontario is, not the same as in Virginia. agree?  A good part of Canada is also  close to  or above the Arctic circle, none of the lower 48 is, in-fact at least a thousand of miles away.  Canada also  requires liners in Every masonry setup. They also have  greater distances to combustibles, than we do, from 36" to 48".  Are you saying we should enforce Canadian code? Almost every masonry chimney application would be illegal here. Almost every clearance to combustibles would be illegal. The reason aditional metal liners are required, and not here, is the colder climate conditions.. So at what point do we use their a codes, and can they even apply here to our warmer climates. It obvious the Canada recognised theire climate to require  different code. Could it be outside air colder more density exhibits different characteristics the warmer more moist air here? Please quote   reference to studies here. The Virgina Tech study  was a Canadian study  but where here or Canada?. As a code official what do you want me to do?  choose to ignore code and enforce other codes?  Enforce what I choose. I enforce what is written. Now if you want to introduce your finding, I would be more than willing to help you go threw the code revision process. I have read these studies  before and they  present valid points.  None of these studies went far enough to have multi  openings on different pressure sides of the homes as I suggested. These studies were doom to failure because wind does not  blow in the same direction at all times.  One outlet is not enough.  and all your fact finding is proving this. Find me facts where multi openings are failing.

tradergordo We agree on many common issues , like correcting poorly  installed  stoves/  venting systems.  Remember the min Verticle height provides of min satisfactory opperation, not optium.  Higher chimneys draft better, interior chimneys draft better.

 What about location factor of the chimney requiring outside air? exposed chimniys need more assistance and draft poorer than interior chimneys EVEn the NFPA reconsise this  fact the way ther revised the 2003 cros-sectional codes


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## KP Matt

Elk, I'm surprised at you - Vogelzang = bad, Ventless gas heater = acceptable? (goodhumoured ribbing) 

I'd venture a guess that the primary reason ventless appliances have automatic switches is not because they deplete oxygen levels but because, by definition, they pump carbon monoxide into the air. Humans can survive reasonably low oxygen levels (ever been in the mountains) but carbon monoxide?


For the CMHC studies they are here:

http://www.cmhc.ca/publications/en/rh-pr/tech/95-202.pdf

http://www.woodheat.org/outdoorair/outdoorcmhc.htm (actually just excerpts - the full report is available elsewhere online)

And for good measure, a less than glowing piece on unvented gas fireplaces: http://www.cmhc.ca/publications/en/rh-pr/tech/97-116-e.pdf

What I'm wondering is, if modern stoves in modern houses NEED an OAK (and I will assume that stove efficiency gains have outpaced house insulation improvements), how could open fireplaces have EVER worked at all, given the fact that they use SO MUCH air?


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## stuart

This brings me to a question this past winter i had my stove up on high,as i was sitting i can hear the room expand or contract with the warmth, realy warm, could i need fresh air input? If i need to install fresh air pipe ,1 1/5 round pipe can i run it out the side of the house about 10 ft from stove to get fresh air from the breez way??


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## elkimmeg

This being a  familly forum, I can not truely express what I think about Ventless heaters. I can say you will not find one in my house.

 In time the Vogelzang  and scandia  pieces of ------------ stoves will re appear in post. ITs been almost two months since I comented about them.

 There are situations /conditions where OAK are a solution.  I think of them as suplemental air unless, the entire stove is designed and recieves  all combustion air from outside, then it is spected and mandatory to be installed per specs. 

In the office I will copy a report certifying a home to energy star standards in the mean time I am sure a web search has that info , for those who can not wait. I have seen them put  a rubber membrane blatter in the door way with a blower to suck out the air. I have seen magnetic  rubber sheets blocking  HVAC vents testing leakage. I have seen balance reports  of duct work for every room
 In order to qualify for energy star homes the HVAC duct work can only loose 12% in heat transmission,  the normal is up to 35%
 I have worked with the builder and HVAC contractor and come up with solutions that achieved this 12%.  First we designed the placements and duct run outs to be the shortest possible. Second to reduce friction, all bends 90 degrees or more are made with smooth galvanized elbows, This reduces  friction and maxumises vollume bending a flexible duct oblongs the diameters and increases friction and restricts air flow. All joints are sealed with duct mastic, including metal elbows. All  take offs are gasketed and duct sealed.
 All flexible ducts are R6.0 not 4.2. Plemums and trunk lines are R6.0, about 2" of foil wrap fiber glass insulation. The furnaces and exchangers are caulkked or masticed preventing more leaks. High low returns  with dampers distrobute heat or Ac more evenly. 
Really its too bad  code does not govern placement. or I could really enforce more energy saving effeciencies. I do have the power of suggestion and the ability to educate. 

 The international codes does require an outside air feed for new construction in fireplaces. IT's up to the user /owner, whether he uses it


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## tradergordo

I wrote to John Gulland hoping he might share some more thoughts with us on this debate.  Doesn't look like he has much to add to what has already been written.  I believe John also has in the past been a contributor to code changes related to this subject (in Canada).  I think his point makes a lot of sense in that the burden of evidence should be on the outside air proponents to do some actual research instead of just talking about anecdotal evidence.  The reason so many jurisdictions dropped outside air requirements from code is because of the research already done in this area.  This research is now pretty old, and stoves are more efficient today.  You would think the state of Washington, which requires OAKs could fund a study, or perhaps an insurance company as was done in Canada.

Anyway, this is what John G. had to say via email (bold was added by me):



> Hi Gordo,
> Thanks for pointing us to that thread. It has been quite a while since I read an exchange like that on outdoor air supplies and it reminded me of many similar debates over the past 15 years at training courses, workshops and standards committee meetings. The arguments of the outdoor air proponents are always the same: opinions backed up by undocumented anecdotes. I really wish those who promote outdoor air supplies would finance some decent research on the subject in the attempt to challenge the studies that demonstrated the problems with outdoor air, but after all these years no one has.
> 
> I used to promote outdoor air back in the 1980s until the research was done in Canada that debunked the whole thing. *I don't have a vested interest in the issue, except that I don't care for the idea of people having to pay for a tradesman to punch a hole in their house wall and then ascribe magical properties to it. *
> 
> I look at it this way: I've done what I can do to popularize the research and there is not much I can add to what I've already written. Also, in Canada the main codes and the WETT training program don't promote outdoor air, so I figure my work here is done. Obviously I have no say about or mandate to intervene in the US discussions. I certainly have no desire to engage in that debate again. Feels like old news to me.
> 
> Thanks again for pointing us. On one hand it is a little sad that the debate still rages after all these years, but I feel good about not having to be involved any more.
> 
> Regards,
> _John Gulland
> The Wood Heat Organization Inc.
> www.woodheat.org
> A non-commercial service in support of responsible home heating with wood _


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## KP Matt

I think this is what Elk was referring to, Blower Door Tests:

http://www.eere.energy.gov/consumer/your_home/energy_audits/index.cfm/mytopic=11190


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## webbie

tradergordo said:
			
		

> I wrote to John Gulland



John is the God of house pressurization and has written books and worked for the Canadian Government and other such orgs in relation to this. You can rest assurred that his conclusions and opinions are as close as you will get to the facts.

In other words, it's like asking Elk about nail spacing........if he doesn't know, then no one does!

Given this long thread, are there any budding authors among us who want to try and distill it all into fact and give us a new wiki article?  I'm pushing the wiki, because combined knowledge, edited by folks who like to write, is the cat's meow on subjects like this.....

Please....pretty please......

http://www.hearthwiki.com


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## KP Matt

Shouldn't the Wiki have (1) a "Pro-Outside Air" and (2) an "Anti-Outside Air" entry? As well as something describing (3) the range of Outside Air Kits available, and (4)a review of the history and current state of code, industry acceptance, insurance and any related information pertaining to the requirement to/not use outside Air? 

That breaks it into more manageable pieces, and should preclude problems of bias.


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## webbie

KP Matt said:
			
		

> Shouldn't the Wiki have (1) a "Pro-Outside Air" and (2) an "Anti-Outside Air" entry? As well as something describing (3) the range of Outside Air Kits available, and (4)a review of the history and current state of code, industry acceptance, insurance and any related information pertaining to the requirement to/not use outside Air?
> 
> That breaks it into more manageable pieces, and should preclude problems of bias.



Well, it can all be one article and we can add/edit. First it could say what it is and why it might be used in mobile homes and such - then it could mention use for wood and pellet stoves.

It could mentions the questions and the general conclusion of the experts (that most don't need it).

It could eventually cover most of the bases.


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## elkimmeg

With all the discussions, I want to re state my stand. If inside air satisfies code and proper opperation  and draft, I see no need for oak
If an insert is spected only to function with outside air then outside aire is the only correct way to install it. If your home is modern and fairly tight possibly the optional outside air kit should be considered, if you have spillage, hard startups  and draft issues. 
I look at outside air as  supplemental. I also believe that the outside air feed should split to reflect presurization of prevailing winds that two openings are necessary on opposite sides of the home to achieve effectiveness.


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## elkimmeg

KP Matt said:
			
		

> I think this is what Elk was referring to, Blower Door Tests:
> 
> http://www.eere.energy.gov/consumer/your_home/energy_audits/index.cfm/mytopic=11190



Thanks  thats exactly what I witnessed the one with the gages 

BTW these home earned a 5 star Home Energy Rating Certificate an effeciency rating of 89%. Some ranked the top rating 5 star plus 90 to 100%. Check out how they were rated goggle rem/rate   July one New revisions were made for qualifying energy star homes.

 As things turned out today the builder and hvac contractor called me today to ask what I think they should do to make further improvements for the up commind revisions. My suggestion was to switch to Trane furnaces.  They carry one of the highest Energy star ratings. Another unknown to most, they are made by American standard. Almost identicle to American standard but cheaper. 

 To me any extra money spent for Trane is worth it. Simply put quality is worth the additional price.  better than Carrier.


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## begreen

Trane is good equipment, though from the quotes I've been getting, the are currently marked up very highly in our area. I also like York's new Affinity 8T systems. They are as efficient and offer a better value while still having the same Copeland compressors and Johnson controls.


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## elkimmeg

Yess Begreen You can subsitiute York for Trane   maybe better bang fot the $$$ American Standard it great equipment. But for pricing. I will think of others


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## Woodstove master

I had to join this forum to post in this topic. It has been a huge debate as I see. I have done a tone of research about outside air for combustion and have a very good understanding of it and also how the sparks may have come out of the outside air vent.

First I will give my learned and proven points of why outside air is a must. Some are in this post but a few are new.

1. Out side air venting will provide the needed air supply to a stove much better than a tightly sealed home with inside air.

Remember we are all here to get the most heat for our money. To heat efficiently we want all drafts sealed. As we do this we decrease the ability of the wood stove to get the required air needed for adequate combustion as we create a negative pressure in the home. When this happens we pull outside "cold" air into the home. I know of many people who have wood stoves and pellet stoves installed without the outside air kit. All of them complain about the heating ability of the unit and that the outside rooms are always cold.

2. Outside air vent will not blow your freshly heated air up the chimney. When we use inside air for combustion we are using the air we just paid to heat. Now we are sending it outside! I want to keep the air I just heated with the stove in the house. 

3. Outside air is usually much colder than the inside air and thus will be higher in oxygen content. "Cold air is more dense and has a higher % in oxygen". This will help the fire burn more efficiently. The more oxygen you introduce into a fire the hotter it burns and it is more efficient. This will also reduce your chances of developing creosote and having a chimney fir by increasing the flue temperature above where creosote develops. Yes the air will be pre-heated some on its way thru the stove but will still be higher in oxygen content. I don't care how cold the inlet air is as it cannot decrease the temperature of an 800 degree fire in any significant level.

4. When outside air is used, the stove then creates a natural positive pressure inside the home effectively sealing out any cold air from being able to enter through cracks, leaks in the homes exterior. "warm air has more pressure" When compared to outside cold air it is significant enough to make huge differences in heating capability.

5. Humidity changes. An outside air vent will stop the home from dehumidifying. When inside air is used you are creating negative pressure pulling in cold "dry" outside air. Not only will it cause some health issues in some people but it can create a long term fire hazard. When we create the high temperatures we do near and especially above  the stove it slowly over years will cause the flammable materials to dry over time at the cellular level eventually causing a fire. The material actually changes its composition lowering its flash point over time to a point that will ignite during normal operation of the stove. Most fires that start near wood stoves will not occur for 6 to 10 years after installation due to this effect. Most start in the ceiling around the area where the chimney goes through and or wall. I am A 16 year Firefighter / Paramedic. I must also mention that dry air seems much cooler than it would at normal humidity levels. When my stove had inside air I could not keep it above 20% to 30% humidity in my home even with a 12 gallon dual fan humidifier. Now I can save electricity of running that unit and the more humid air is more comfortable. When at normal humidity I can keep the house at 70 to 72 and be comfortable. With inside air and 25% humidity I had to keep the house at 85 to 90 to fell comfortable. This uses more fuel than necessary.

I have used the same stove both ways. For the first year it was inside air. It did not heat well at all and used a lot of wood. I have a 1500 sq/ft mobile home that is well sealed. It did not matter, the negative pressure still pulls air from the outside rooms and they were very cold. You will use less wood by using outside air as you can see the advantages it gives. For the past 4 years I have used an out side air boot. The stove has almost doubled its heating and I use a third less wood. I had to make sur to seal the outside air kit 100% to make sure it will not draw any inside air. The kits are not built very well as far as how well they seal. I used 600 degree silicone sealant at all connections. Started a fire and then used an incense stick to check for leaks. If there were any leaks you would see the smoke enter the unit at the leak. I have a 100% sealed system. Now I get to keep all the air I heated, it is safer, more efficient, and I no longer have to use A huge humidifier as I did the first year as the home got so dry.

I cannot tell enough of how important it is to use and outside air kit installed and sealed correctly. I have all info needed to settle this debate above and more if need be.

in my next post i will go over the back drafting problem.


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## Woodstove master

By the way I have an Avalon wood Stove the "rainier". This is a high tech double walled stove.


Now for the sparks from the outside air vent. I do not doubt for a minute that this actually did occur as i have seen it many times myself but it is not related to the outside air boot, it happens with inside air too. If this is a new stove then i must say that it must have been all the wrong circumstances at the same exact time to cause this. If an older stove with a poor deisign then one or both of the following.



1. Stove design does not reduce the chance of back draft.  

2. Chimney is not high enough above the peak of the roof to stop the chance of a downdraft. Local codes here in New York state that the top of the chimney has to extend beyond the peak of the roof by no less that 2 feet. 

I had an old single wall wood stove that had a square hole in the back of it with a flap that controls air inlet. I have had on windy days sparks fly out this hole inside my home. This scared the heck out of me and started the research. This was such a poor design that you could look into the hole and see embers! A small downdraft because of a chimney that was lower that the peak of the roof and "bam!" sparks fly backwards. My research led me to extend the chimney by one 4 foot section bringing the top 28" above the peak of the roof. It was hard to start fires in this stove also. More on that below.

A downdraft occurs in this situation when the wind blows from the opposite direction of the chimney from the other side of the roof to the side the chimney is on. When this happens the wind speeds up over the peak of the roof as it was passing over an airplane wing creating down force in this case. The wind hits the chimney at a pressure higher than the draft in the chimney and it runs in reverse.

Having the top opening of the chimney terminate at least 24" above the peak of the roof will keep it above this downdraft preventing this from occurring, the wind will just blow by the base of the chimney. 

This 2 foot rule applies no matter how far you are from the peak of the roof. My girlfriend has a 45 degree angled roof  on a two story home and the chimney was at the outer edge of the home. This made us have to make the chimney 16 ft tall and use cables to secure it to meet this rule and prevent a back draft. Safety first. OF course more expensive but better than placing a two foot section above the roof and having it downdraft and burn the house down. 

You can imagine the effect if both of the above were true in the same application it would be a recipe for disaster.

I live on top of the largest hill in the area and the wind is always blowing. So bad at times during winter storms to blow shingles off the roof, siding off, and twice broke windows. Never once have I ever had any back draft of any kind with my proper installation. If the chimney is tall enough it should produce a draft more powerful then wind blowing by the opening providing it is at least 2 ft above the peak of the roof. This will also help you start the fires as an adequate draft will increase available oxygen to start the fire and keep it going. If your chimney is high enough above the peak of your roof and tall enough from the top of the stove you should get such a strong draft that it will actually increase with the wind blowing. I know this is true with my unit in the fact that it has to be turned down by the air inlet when the wind rips up as it increases the temperate of the fire by increasing the draft. I hear the wind blow and watch the air increase from the air inlet in front of the stove making the fire brighter. When wind blows by a properly installed chimney on a cold windy night / day it will actually create a vacuum at the opening if the chimney by the act of the wind blowing by and helping to increase the exit of the hot air. "cold hard science proves it as hot air rises. When given enough hight to do so can increase dramatically. Just like a gun. The longer the barrel, the more time the bullet has to increase its speed and energy. This goes the same for chimneys. My answer to any stove problems would be the hight of the chimney and or outside air.

I have a newer stove also and agree to prior post that it is nearly impossible for a back draft to cause sparks to fly out the inlet. There is just too much space for it to have to travel to get out of the stove the wrong way. You would have to create a vacuum so strong that it would suck the coals from the bottom of the stove up 14" to the air wash inlet, through the screen in it down the sides, around a baffle then through the outside air boot. 

I say it is much safer to have the sparks have to fly through the extra space of the outside air inlet and deposit outside rather than not having the outside air boot and having the sparks land inside my house where they are much more likely to cause problems.

I think It is settled! Outside air is a must. I have seen many chimney fires and fires caused by improperly installed chimneys or stove and no fires originating from a direct cause of an outside air boot. It just does not make sense.


----------



## Woodstove master

One quick note on sealing the outside air kits. You need not only seal the outside air boot but the old inside air inlet also as that will not longer be used. If you do not properly seal this, it will defeat the purpose of the outside air kit.

My kit came with a plug that slid over the front air control nob and is supposed to seal the square inlet. Well it does not fit well at all. The hole for the nob shaft was 3 times too big creating a huge air leak. I used 600 degree silicone to seal around it. I then used a rubber gasket around the knob rod opening tight enough to still allow it to move and also seal the air entry.

It does not end here. You must also check the bottom of the stove for air inlet leaks with a good strong fire going after the outside air boot is hooked up and the old inside air inlet sealed. Many stoves have breakouts in the bottom for other accessories like ash pans and blowers. You have to make sure that the breakout does not run along the path of the outside air or you will have a major leak. Mine had this exact problem and had to be sealed off. I ended up having to seal 6 different places around the front and bottom of the stove to ensure that it only gets its air from outside. Maybe this is why the efficiency of these outside air kits are being scrutinized. Installing them as per given directions will not do the job 100%. Without that how can we judge the effectiveness of the product?

Remember to just start a good fire and light an incense stick. You want the fire to be burning well with the air inlet wide open to create a good draft and look for leaks. If there are leaks it will suck the smoke into it. Place the smoking tip of the stick around the front , bottom and outside air boot. You should only see the smoke rise not go into any vacuum leaks. If you find one seal it, find another, seal it till all leaks are found. Now you will have a true outside air boot / kit. P.S. Turn off the blower and or all fans you have in the area to have a calm area without drafts and watch where you breathe as not to blow the smoke all over the place.

Any questions just ask.


----------



## builderbob

Webmaster said:
			
		

> tradergordo said:
> 
> 
> 
> 
> I wrote to John Gulland
> 
> 
> 
> 
> John is the God of house pressurization and has written books and worked for the Canadian Government and other such orgs in relation to this. You can rest assurred that his conclusions and opinions are as close as you will get to the facts.
> 
> In other words, it's like asking Elk about nail spacing........if he doesn't know, then no one does!
> 
> Given this long thread, are there any budding authors among us who want to try and distill it all into fact and give us a new wiki article?  I'm pushing the wiki, because combined knowledge, edited by folks who like to write, is the cat's meow on subjects like this.....
> 
> Please....pretty please......
> 
> http://www.hearthwiki.com
Click to expand...


So, taking as gospel then that outside air accomplishes nothing, I apply that to the Travis Fireplace Xtrordinaire zc woodburner.  It uses air cooled chimney, two 6 inch outside air ducts for shell cooling, and one 6 inch outside air duct for combustion.  I conclude the Travis FPX sucking in all this outside air is sucking in a lot ot it for no good reason?

Let the firebombs begin.

BTB


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## elkimmeg

First of all welcome to the hearth.

 I agree with a lot of what you are saying but there are points I will disagree with  These points apply to two separate
 scenarios A newly tight home and an older more leaky home 

 a tight home is  the most beneficial for outside combustion air.  The lower you stove is situated  below the neutral presser plane the more benificial outside air becomes

 situations when competing appliances vi  for the combustion air it is beneficial for combustion air coming from outside

The next issue is health of inside air the tighter we build homes the less air changes occur.  the level of stagnant inside air increases   As we move to improve the insulation envelope,

 we have to deal with stagnant inside air issues .Years past mold never seemed to be a problem because homes were not as tight
 Now if my stove combustion air demand causes leakage infiltrations of fresh air,  that may not be all that bad.  ITS like we got so concentrated  at leak prevention, that it caused other issues like indoor health. Now tight home rely on bath exhaust kitchen hood exhaust to try to make up  fresh air changes. I here you about exhausting heated inside air, but that may not be a bad trade off for healthier air.

Lets discuss the outside air kit  It is usually installed in the most convient location to the appliance. No thought process to positive and negative air pressure effect caused by wind hitting the home Using the same principal for chimney height when wind hits a side of a home that is positive pressure zone. As it deflects around the home ,the reverse side becomes a negative pressure zone. Knowing cold air has a northern direction and warm air has a south direction the positive and negative sides of the home change with wind direction so where do you place the inlet?

 For one, you do not want to place in on the negative side but this is impossible to do when wind directions change
 Here is where the design fails the outside air dust should be teed and have two inlets on opposite sides of the home fitted with a one way flapper device to prevent  negative pressure inside air escape or a combination of inside  combustion air when the outside air location is in the negative pressure zone again the one way flap is engaged.

Unfortunately, I mentioned many times no thought is given to the location of the outside air inlet location  other than for convience.

What you said about outside air is only partially true  it is designed flawed

Aslo it is true that if all combustion air is take from the outside there is less leakage in the home's envelope. Again this can be debated as whether it is better to have air changes and healthier indoor air.  there is a trade off here as to which is the worst of evils.

the leaky home  one dies not need outside combustion air but maybe using a correctly designed one  would prevent leakage.  There has to be a balance here healthy inside air and leak prevention.  

You explained the chimney height conditions. There is nothing I can add to what you have said. It is well explained.  This post runs 8 pages long and a year later we are still debating outside air. Some appliances require it, per the listing and manufacture specs. There is no debate  from me where the appliance is tested and requires it. As an inspector I require it.

I also look at the indoor volumes to determine sufficient combustion air is available and factor the current existing demands. I will require  the additional inside air provisions or outside air provisions it the demand cannot be met completely within   Cellars  with multi combustion appliances are problematic locations one they are in the negative pressure zone and two other appliances may already use the  existing volumes. No wonder n basement location stoves under preform. start adding playrooms and  partitioning off boiler rooms and it creates all kinds of negative problems and increases health risk of back drafting appliances in the boiler room You bet I look at those situations and require corrective measures or I won't issue a permit for the new stove


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## Todd

Welcome Wood stove master,
I have seen this debate go back and forth for years and I still can't figure it out. I use a Condar air supply ventilator that is located about 3' away from my stove. Some people say it's just another open window, but being so close to the stove I think it supplies combustion air to the stove, eliminates negetive pressure in my basement caused by other appliances besides the stove, and helps with the stale air problem. I looked into the OAK for my stove and if I installed one it would ruin the looks of my hearth. As far as firewood consumtion, I think that's great your saving fuel, but I only go through 3 full cords burning 24/7 as it is, and I doubt I would go through less than that if I installed an OAK.

On the other hand, I have a fireplace on my main level that use to really suck some air out of the house. It was so strong that it would pull air and smoke down through the other flue and out the basement stove. Not good, so I did modify it with some air tight doors and outside air through the ash dump. Problem solved. Now I can burn both if I want. With fireplaces I can see the advantage of an OAK, but woodstoves use much less air and I don't really know if it's an advantage.


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## Highbeam

The OAK is required in my jurisdiction. It is really no problem to install and mine pulls air from a ventilated crawlspace so there are no wind currents. I don't think the plumbing on the hearth is ugly though it is certainly noticable.


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## Woodstove master

You all make very valid points that I mostly agree with. One thing I am not sure of is how much air these new stoves pull as one mentioned. I can only speak from experience and I have proved it in repairing several installations either myself or a recommendation after inspection. They all improved significantly.

"So, taking as gospel then that outside air accomplishes nothing, I apply that to the Travis Fireplace Xtrordinaire zc woodburner.  It uses air cooled chimney, two 6 inch outside air ducts for shell cooling, and one 6 inch outside air duct for combustion.  I conclude the Travis FPX sucking in all this outside air is sucking in a lot ot it for no good reason?

Let the firebombs begin.

BTB "

I love that! I thought I was the only one to use 6" outside air for shell cooling, I was wrong. I did not mention It on my last post as I did not think much would happen since the last post was a long time ago. This setup also saved me some cold outer rooms. I know this as I did the outside air for combustion one year and the air cooled shell with outside air a year later. Both increased the temp of the outer rooms and the temp of the main room the stove is in. 

As far as sucking it in for "no good reason"? Who cares, it comes from outside and goes through the chimney and out the top back to the outside.... You have a safer and cooler chimney to avoid house fires. The later is the benefit that does not have me worry if I have a fire in the stove when not home. The shell of my chimney can be touched with the bare hand this year. Before the outside air, I would need to call "911" after touching it. A major safety improvement and no more inside hot air to cool the shell.

Great debate guys! I got more than I bargained for. I look forward to more reading / learning.


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## elkimmeg

You are defeating the purpose of the chimney. We all know a warm chimney draws better. Cooling it down negates it ability to draw cooling it down, also aide the the development of creosote

Pick you poison chimney fire from creosote  or cooler = safer.  Now if you need outside air to cool that chimney down to be safe, then I suggest there exist other problems, like too close to combustibles. 

 You also failed to address the wind effect upon a home in relationship to the outside air inlet. Never addressed the one way flapper.  You make statements but don't address issues I presented. 

I welcome good constructive debate we all can learn. Nobody has all the answers. This is not anti outside air, as I stated there are situations that require it . I just wish the deliver system was designed correctly and not for convience ,a system that addresses the down falls


  These stove are designed and the designing is an ever going process, where less is better. The longer heat remains in the stove the more is delivered to the living space, One way to hold heat in a stove is to reduce  inlet air, less air exiting up the chimney.  Really its not all that much.  All modern appliances have reduced inlet or combustion air requirements. 150k Btu furnace high efficiency  gas furnace only needs a 2.5" pvc combustion air inlet.

This in not bring it on that is the wrong approach this is an educational discussion

 another point you did not address healthy inside air


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## stoveguy2esw

cooling a chimney is never a good thing, cooling the outer shell of a chimney to give closer clearances isnt necessarily a bad thing as long as the internal "working" part of the flue can be kept at a proper temperature. personally , i would not want an "air cooled" chimney it brings too much margin for error into play. intake air is going to vary in temperature and stack temps will as well, i'd hate to see what would happen in the extreme cold air flowing to cool and a lower stack temp from a small fire for example. puts too much on the operator to maintain large fires even when not needed.

now outside COMBUSTION air is a different animal all together, there is absolutely no factor that is worsened by outside combustion air. cooler air is more oxygen dense creating more complete combustion, having OCA defeats negative pressure (which exists in all homes, not just new ones) and also doesnt waste heat from ejecting preheated air through the flue to outside. i would recommend it on any device that it could be equipped with it


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## BrotherBart

Edit: Asked a question and then found the answer.


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## builderbob

stoveguy2esw said:
			
		

> cooling a chimney is never a good thing, cooling the outer shell of a chimney to give closer clearances isnt necessarily a bad thing as long as the internal "working" part of the flue can be kept at a proper temperature. personally , i would not want an "air cooled" chimney it brings too much margin for error into play. intake air is going to vary in temperature and stack temps will as well, i'd hate to see what would happen in the extreme cold air flowing to cool and a lower stack temp from a small fire for example. puts too much on the operator to maintain large fires even when not needed.
> 
> now outside COMBUSTION air is a different animal all together, there is absolutely no factor that is worsened by outside combustion air. cooler air is more oxygen dense creating more complete combustion, having OCA defeats negative pressure (which exists in all homes, not just new ones) and also doesnt waste heat from ejecting preheated air through the flue to outside. i would recommend it on any device that it could be equipped with it



Darn good discussion, everyone!!  Very informative.

BTB


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## WILDSOURDOUGH

Wife and I are on our second year of building "The Last Home" We built an ICF (Insulated Concrete Form) Basement-(stove and us living down here now- we hope to move upstairs by christmas but stove will stay down), SIP walls for the house and standard truss and R 38 roof with standing seam metal top. The house is TIGHT now and I am installing my Lopi Leyden with a 4" air intake from outside to the 3" air fitting on the stove bottom. I am doing this because- 

1. I have a Gas kitchen range, an outside venting microwave (vent hood kind) and 3 bathroom fans- all sucking air OUT>
2. The manual talks about it, the laws in Washington state and Manufactured Homes require it. (maybe Canada too)
3. This dissussion has convinced me that it's the right thing for me.

May provide better combustion (or not), but at least it won't be drawing my heated air from the inside of the house out- kinda why fireplaces are not so efficent eh.


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## kevinmoelk

Howdy everyone... I'm not going to read through 9 pages of responses, I'm a little late to the dance...

In any case, let me just offer my own personal experience.  I live in WA state, so an OAK is required.  No big deal.  I ran a 3" OAK to my stove and let me tell you it burns great.  For experimental purposes I've disabled the OAK before and since I live in an older home you can feel the air leaking past windows and doors.  When you open the door a big "whoosh" of air will come in as the pressure equalizes in the home.  With the OAK in place, these problems do not exist.  Suffice it to say, though I'll be leaving WA state next year to live in Maine, I will install and use an OAK there too.

-Kevin


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## elkimmeg

I have been thinking about another point said Again the original point is true but not applied to wood stove combustion
 cooler out side air contains more oxygen a true statement no disputing that.

 but in the case or wood stove burning cool is not necessarily better .  In order to achieve secondary combustion the stove temps inside the fire box has to 
 exceed 1000 degrees Combustion air  outside fed or from with in many stoves channel it around the fire box super heating it.  Cool air coming out the secondary air tube would not promote secondary burn but retard it cool air entering the cat combustor chamber or secondary combustion chamber would prevent this secondary combustion from occurring

 for secondary combustion these stoves channel that air around the firebox to super heating  to ignite secondary combustion.  In this case ,using heated room air would require less heating to  temps. It would also  not need to dissipate additional heat from the fire box to heat it There is no advantage for secondary combustion using cold outside air including the extra oxygen.


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## tradergordo

"Woodstove master", first, welcome to the forum, I appreciate your contribution.  But most of your arguments (possibly all of them?) have been debunked.  I think Elk hit on the important things already - indoor air quality is #1 for me - and your setup is downright awful - a super tight home with absolutely no ventilation is a recipe for problems.  Couple no ventilation with high humidity, and you have even more potential for problems. 

As for the "back draft" issue - as Elk mentioned - you did not address the problem at all in your comments - chimney height is irrelevant to the wind induced negative pressure problems related to OAKs (especially a SEALED OAK like you have).  Although I think at this time this issue has to be considered somewhat irrelevant because thus far no one has been able to produce any documented fires that resulted from such a configuration...

Several (possibly all of them now?) stove manufacturers advise against sealed outside air connections.  Most outside air flanges on new stoves are engineered to prevent a seal (sounds like yours was too!).  Why do the manufacturers not recommend sealed OAKs?  As a firefighter, do you really think its a good idea for people to be modifying their stoves?  Why do all of the owner's manuals warn against modifying the stove?

I haven't searched all of the manufacturers, but here is a statement from Jøtul on this subject:

_"Jøtul North America ONLY requires the use of the outside air kit where required by local code and *does NOT promote or recommend the use of a directly connected outside air source*. All ducting must be non-combustible and clearances to combustible materials must be maintained."_


Do you claim to know more than the industry professionals who build our stoves??

(I also find it interesting that from what I've seen, almost NO ONE who uses an OAK follows Jøtul's advice in maintaining clearances on their OAK ducting - typically people use super thin dryer vent type material with no special consideration for clearances to combustibles. But as I already said, I think this is a minor and possibly irrelevant point)

p.s.  Very few natural gas furnaces use OAKs, and they require SUBSTANTIALLY more air than your woodstove.  Why do you think this is the case?


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## Jags

elkimmeg said:
			
		

> I have been thinking about another point said Again the original point is true but not applied to wood stove combustion
> cooler out side air contains more oxygen a true statement no disputing that.
> 
> but in the case or wood stove burning cool is not necessarily better .  In order to achieve secondary combustion the stove temps inside the fire box has to
> exceed 1000 degrees Combustion air  outside fed or from with in many stoves channel it around the fire box super heating it.  Cool air coming out the secondary air tube would not promote secondary burn but retard it cool air entering the cat combustor chamber or secondary combustion chamber would prevent this secondary combustion from occurring
> 
> for secondary combustion these stoves channel that air around the firebox to super heating  to ignite secondary combustion.  In this case ,using heated room air would require less heating to  temps. It would also  not need to dissipate additional heat from the fire box to heat it There is no advantage for secondary combustion using cold outside air including the extra oxygen.



Elk, I think you are giving too much credit for a 40 to 80 degree temp. differential (meaning outside air is 40 to 80 degrees colder than inside air).  When looking at the big picture of 1000 degrees for secondary combustion, I really doubt that the difference in temps from outside to inside will be the deciding factor in the reburn process.  Does it make a difference? Sure, if you are a piece of electronic monitoring equipment, but probably not to us humans.  Possibly the temp difference would cause the end of "fire" cool down to happen a little sooner, but heck, if your gonna be heating, its time to throw another log on anyhow.  Just my $.04.


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## elkimmeg

Jags I agree but the point is that inside air was at least equal for secondary burning as outside air

 Don't get me wrong outside air has a place and valid use.  It is not one size fits all situation for requirement.

Like I said this is to be an educational debate for me. the rest, and woodstove master ,who resurrected this debate

Woodstove master put a lot of though into his post make some valid points but is now finding there are other valid concerns.

 what happens if the OAK is on the leeward side of a home with decent breeze the negative pressure side it is possible to draw from that stove  to the outside it could actually starve the stove

 that is why I suggested two opening on opposite sides  with the one way flapper and that is the reason it has to be non combustiable and clearance distances required incase negative pressure draws combustion air out of the stove


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## Jags

Agreed, this has been a good discussion.


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## tradergordo

Jags said:
			
		

> I think you are giving too much credit for a 40 to 80 degree temp. differential (meaning outside air is 40 to 80 degrees colder than inside air).  When looking at the big picture of 1000 degrees for secondary combustion, I really doubt that the difference in temps from outside to inside will be the deciding factor in the reburn process.  Does it make a difference? Sure, if you are a piece of electronic monitoring equipment, but probably not to us humans.  Possibly the temp difference would cause the end of "fire" cool down to happen a little sooner, but heck, if your gonna be heating, its time to throw another log on anyhow.  Just my $.04.



The stove will use the same amount of oxygen for a given burn (heat output) regardless of the air temp so the "density of oxygen" in the air is irrelevant.  Think about it this way, lets say you hooked up a tank of pure oxygen to your sealed outside air flange.  Wouldn't you just be forced to turn your air control all the way down to control the fire (assuming it could be controlled)?  

You control the burn with your air control, it doesn't matter how oxygen dense the incoming air is because you will adjust for it either way so that you get the same heat output.  Besides, the cold air immediately heats up and is then no more oxygen dense than the room air, I think people vastly overestimate this "oxygen density" difference between cold and warm air.


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## delwalk

How does this conversation apply, if at all, to wood pellet and corn burning appliances? For reference I've been looking into the Selkirk Direct Temp system for combining the exhaust flue with preheated air intake for my pellet stove. I'd be interested in whether or not such a design might alleviate the problem with wind induced pressure differentials since both intake and exhaust are subject to the same pressure.

Someone brought up the idea that oxygen concentrations are higher at low temperatures than at high temperatures. That's true, sorta. The amount of oxygen by volume is greater at low temperatures but not in relation to other gases (i.e. percentage). If outside air containing 4.5% oxygen is pre-heated by passing around the combustion chamber it is still 4.5% oxygen (assuming minimal loss to oxidation of the appliance) when it reaches the fuel. Combustion efficiency is improved by raising the temperature of all of the reactants and increasing the amount of time the reactants are in contact with one another. Air preheating is used in a variety of commercial furnaces to increase combustion efficiency and is one part (the other being oxygen enrichment) of the improved efficiency of modern blast furnaces.

It seems reasonable that the indoor air would have a slightly lower oxygen concentration than the outdoor air for a given building with oxygen consuming occupants. However I don't know that the difference in oxygen concentration is great enough to adversely impact the appliance.  Lower concentrations of oxygen should just mean increasing the air flow to the appliance but I doubt the difference between indoor and outdoor is enough to cause more than a point or two different in efficiency, if at all. Assuming the stack temperature can be kept high enough to efficiently exhaust flue gasses and prevent creosote condensation it would seem to me that a system that combines both into a single pipe, such as the Direct Temp product, would be ideal. I don't believe there is a similar product for wood burning appliances unfortunately.

Someone please let me know if I'm completely off base here. It's been some time since I've taught chemistry and I haven't had opportunity to apply that knowledge to wood burning appliances.


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## tradergordo

" I’d be interested in whether or not such a design might alleviate the problem with wind induced pressure differentials"

Yes it would.  And as you've stated, cooling the flue gasses this way is no good for wood stoves, but might work nicely for other combustion appliances.


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## stoveguy2esw

the cooler air being more dense is a small difference related to the rest of the benefits of OCA. as for reducing combustion efficiency by "wasting" the energy in heating the air is minimal, but look at it this way , if a cubic foot of air has a certain amount of oxygen molecules within it and a cooler cubic foot has more, even heating this air inside the combustion chamber does not reduce the amount of oxygen molecules, it will actually maintain , and would thus increase positive pressure inside the firebox (although it would be a miniscule amount) this cannot hurt draft , only benefit it even in a small way. its really the smallest difference gained by OCA. but its present. leave this as a draw or tie.

the biggest benefit in my mind is the neutralization of pulling in air through leaks in windows under doors and such, this effect will reduce the overall efficiency of the device in an indirect way. heated air pulled out of the house replaced by lower temperature ambient air. for every BTU produced and released into the house, some must go to heating the cooler air being pulled into the structure through leaks, combine that with the BTU's lost by pulling preheated air out of the structure you are trying to keep warm at the same time. this effect will happen anyway due to the effects of other appliances in the home such as dryers, bathroom vents,range hoods etc. now i agree that sealing up a house in some climates could lead to unhealthy interior climates (high humidity and such) to this extent a different method of ventilation would be a viable option. to this end , check out this product  http://www.condar.com/asv.html  ive recommended them in the past for various reasons, mostly in my line of work to help folks with old fashioned units that may not be OAK capable but are in houses that are fraught with negative pressure. its a nice little product. 

i also am not sure that i like the idea of an unsealed OAK kit as well in relation to high wind downdrafting to me to make them totally effective is not an easy task , the downdraft would have the effect of pushing smoke through the intake , this with an unsealed OAK would result in smoke release into the structure, although with a sealed OAK it would have to carry the smoke outside and the resulting heat could be an issue, putting a valve in that does not allow backdrafting out of the stove itself could be an answer, but if this sticks then the stove would starve and pent up energy when released (as in opening the stove door which would feed a starving fire a large quantity of air that could ignite the fuel pent up in the stove would be extremely dangerous acting like a vapor explosion)  a better solution in my mind would be a wind directional cap or a monsoon cap that was designed to protect the top of the flue against this type of downdrafting.

by the way ,im having a really good time with this one myself. great thread


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## Woodstove master

"You control the burn with your air control, it doesn’t matter how oxygen dense the incoming air is because you will adjust for it either way so that you get the same heat output. Besides, the cold air immediately heats up and is then no more oxygen dense than the room air, I think people vastly overestimate this “oxygen density” difference between cold and warm air." 

You do not understand how this works. This is scientific facts that nobody can change. I explain below.

Your secondary burn will only happen if there is enough oxygen left over after the primary burn is done. The more oxygen you have the better the main fire and secondary burn will work.. We are not talking only 4%. Regular outside air has 21% oxygen and will increase density with colder temperatures. Notice I said "density" not percentage. The percentage of cold outside air will still be 21% but the colder air can hold more of it, therefore being more dense with oxygen. Therefore cold outside air gives more oxygen density "per litre" than inside warm air. When humans breathe in this 21% we use 5% of it leaving 16% oxygen exhaled. With a family of 5 in your house you can see how the indoor air can be much lower in %. This will get worse as the % drops. Say it drops to 15%, breathe that in and exhale 10% etc... So to give your fire enough oxygen to have a complete burn it certainly will not hurt to use outside air and guarantee at least 21% oxygen in your inlet that is more dense. So in terms of molecules of oxygen, you will get more the colder it gets. In relation to heating the higher concentration thus losing the concentration as the air would be hotter is false as someone else stated briefly. If the air has 21% on a cold day but is more dense and is pre-heated in the stove this air will still have 21% oxygen, it does not just disappear, it changes in density. When the density changes as the temp goes up that oxygen has to go somewhere in a sealed system, it is taken up by the combustion process. There is no change in percentage by heating the air in a sealed system. The other molecules in the air expand at the same rate as the O2 molecules so the percentage of O2 molecules in air stays constant. So to sum it up: Outside air will always have 21% oxygen regardless of temperature but be able to carry more of it at low temperatures as the molecules are closer together, therefore "more dense". When the air heats up it expands with the same number of molecules of oxygen with less density. You still deliver more oxygen after heating. So this is a two fold positive outcome. I am a 16 year Paramedic also, and I am required to understand oxygen levels in most situations and have 4 years of college in Para-medicine taught by Doctors. I am considered a "Clinician" in NYS as are Doctors. Just in case anyone has any doubt. You can find this info on the web in many forms anyhow.
The outside air can be a big difference. This is why we use refrigerators. The higher concentration of oxygen actually reduces the growth of certain types of bacteria. In emergency rooms you must log once a shift that you checked the temp of the unit with an analog thermometer and must be at a minimum temp. 

Maybe it is overestimated. I give the facts and you be the judge. that is what this is all about. The only way to tell is to conduct experiments to see what the difference is. I do notice that with outside air I get more blue flames in my wood stove then I did with inside air. Blue flames are efficient burning and hotter.


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## Woodstove master

I am not cooling the chimney itself. I have triple wall stove pipe going through and old 12" fireplace shell. It is the outer shell of the 8" pipe that was on the fireplace. This is the part that goes through the ceiling into the roof. It is only about 2 feet long. I have about a 3" space of air around the triple wall pipe from my wood stove that used to get very hot from radiant heat. I am cooling this air space as not to overheat the surrounding structures. I am in no way cooling the inside temp of the stove pipe. The cold air would have to go through the steel outer shell of the triple wall pipe, then the 1" fibre insulation, then the inner steel wall to decrease the 750 degree or higher temp. Not going to happen. With this setup there is no temperature change inside the pipe. The triple wall then goes outside for 6 more feet exposed to outside temp. If cooling this pipe's outer shell was a problem then I would as everyone else would have creosote buildup inside their chimney where it is exposed to outside air. There is no difference. I am just protecting my house.
I live in a double-wide manufactured home and the OAK is under the house in the area protected by skirting, so there is no wind under the house. In my situation the OAK will work fine. I can see the problems with one outside on the wrong side of the wind. Your fix with two pipes is a good idea, I agree.

Regarding the *pellet stove outside air inlet*. I think you will see an even greater change using outside air with a pellet stove. The fire is fan fed by a fan which helps keep greater oxygen levels at the base of the fire to keep it burning at a high temperature. This then goes out the exhaust pipe to the outside. These fans produce a high volume of air. They have to, to be able to feed the fire then exhaust the emissions out the pipe. If you use inside air you are producing a negative pressure in your home and blowing the just heated air outside. This effect is worse with pellet stoves as the fire is fan forced. You might just as well open a window and place a small fan in it all winter blowing outside. I also have a new pellet stove installed in my house in addition to my wood stove. I bought it when I could not find any wood to burn two years ago and also to supplement the wood stove as I routinely work 12 to 24 hours shifts and the wood stove cannot run for more than 9 to 10 hours. For the first week with the pellet stove I used inside air. Man was it cold in the house. The stove had to work at high levels and the outside rooms were freezing. I thought pellet stoves did not work well. I ordered and installed the outside air kit. What a huge difference it was. This stove heats like a monster now. I rarely place it above 3 out of 6 on the temp setting. I now have a thermostat hooked up to it so it runs itself. My step father just bought one and refuses to try outside air. IT is freezing in his house and the stove runs all the time using way more pellets than need be. You must be careful when purchasing the unit though. I got lucky as mine has a sealed outdoor air inlet. I have seen ones that only use what they call 50% outside air. This is stupid as the air will come from the point of least resistance. It will not come down a 10 foot 2" pipe from outside, it will do nothing. The best way to test is to place your hand over the inlet on the back of the stove in the store with it running. If you cover the outside air inlet with your hand it should put the fire out. I have tried this many times and in some stoves it did not change the rate of burn at all. These stoves have holes drilled in them to take air from inside regardless of outside air. This totally defeats the purpose. I have the St. Croix Afton Bay stove. So yes I would recommend 1000% an OAK, more so then an wood stove as they use much more air and are fan fed.


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## Woodstove master

Fire Honor Society
I agree that chimney height has nothing to do with wind induced negative pressure. It is the height in relation to the peak of the roof. If it is lower the wind can blow over the roof and into the chimney IE "wind induced negative pressure". I most certainly did go into detail about it on my post "14 October 2007 02:01 AM" Extensively. If you read this you will see I did not say that the height alone is the problem.

*"Do you claim to know more than the industry professionals who build our stoves??"*

No, not exactly, but just because they build the stoves does not make them "experts". Scientific proof does. It does not mean they will tell you it is ok to modify your stove in any way. I know a lot of companies that you could say are "professionals" in their industry but are idiots. These wood stove companies statements are hugely based upon liability. This goes for most companies, especially these days with all the law suits. They will not give statements or directions on how to modify their stoves in any way as it will place all the liability on them for doing so if something goes wrong. This is why they sell "outside air kits" and explain to follow directions exactly or risk fire / injury / death. This does not mean that if we build our own kits that they are not safe. It does mean that if something went wrong it would not be the liability of the manufacturer due to not using approved setup / kit with the unit. The kit can cost $150 for some stoves. I made mine for $23 and is probably better / safer than what I saw in the store. The kit in the store that came directly from the manufacturer was a piece of junk, very flimsy, not sealed well. This would let sparks out if installed as they state. If a backdraft occurred.

I do believe that if the manufacturers could talk "off the record". They to have modified the stoves themselves to make them work better. The manufacturers are not going to go to the extra effort that I did to make sure my stove seals well, experts or not, it would cost too much money and profits would go down, designs would have to change. This is not to mention that if they go too far they are opening themselves up to further liability if the mods failed and or did not work correctly. The manufacturing process alone does not provide for adequate seal anyhow. Many more things would have to be done. Do the kits work? Yes. Do they work as good as they could? No. Same goes for everything else. There is always room for improvement in any design. Otherwise we would still have the model T. Yes I would modify it also.

The stove companies are wrong? maybe so, but not all of them. Do they back it with scientific proof, doubt it. At least not all of them. The FDA here in America is a complete and utter joke. They approve all kinds of chemicals in drinks and foods these days that are causing cancer and many other diseases and killing people. FDA is a big deal also. They to are looked at as "professionals" but they are wrong....

I only used the *silicone* around the plate that covers the old inside air inlet. This is at the lowest point of the stove in the front where the blower is attached. It is 6" from the base of the firebrick and two plates of steel away. This is the coldest part of the stove ALWAYS! I could put my tongue on it after a full fire has burned for hours and I would not get burned. Not that I would ha ha ha. Therefore there is no heating of the silicone to produce excess chemicals in the house. Otherwise the kit is solid steel.
My house is not as sealed up as you may think. I have 3 vent pipes. One for above my kitchen stove, and one in each bathroom for ventilation. The one way valves are cheap and do not work well. I open my door several times a day to go outside and when I come back in also...The house is otherwise as tight as I can make it. My humidity levels are at the normal for inside a home. It is nowhere near "high". It just stays at a more constant and normal level now that I have OAK. Not to mention the power savings from not having to run a dual fan humidifier to keep 20% humidity in my house, 20% is very low, humidifier could not keep up with what the stove took out without an OAK. 

*"But most of your arguments (possibly all of them?) have been debunked"* I am not arguing, this is a discussion forum!

"All debunked" Please. I don't think they are "all debunked" at all, no way.

I think you need to look at what this forum was designed for. You have turned it into an argument with your statements against me. I do not want it to be that way. You did not even read what I posted, or you did not understand it? I am only stating what I know with actual proof of seeing it work myself many times over. Seeing many house fires as I posted. Some of my writings are opinions, most are "facts". You should be able to tell them apart if you read what I write. I am giving advice based upon the installation and the specific needs. Basically in my case and experience. Not everything works 100% for everyone else. There are way to many variables. Although you cannot change "scientific facts".

In reading this forum someone should be able to base their decision on observed facts and or opinions. This is how we learn, this is how we research to find real world answers. Not by calling the companies. Not by "arguing".


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## tradergordo

I'm getting misinformation overload from reading your posts.  We can definitely agree on one thing - WE NEED SCIENTIFIC TESTING.  So far, I haven't seen any that supports the use of OAKs.   If you have a link to some controlled studies that would shed some light on this, please post it!

"Your secondary burn will only happen if there is enough oxygen left over after the primary burn is done"

With all due respect, you do not understand how modern woodstoves function.  Perhaps you should read up on this.  Secondary combustion air is supplied directly to the baffles/air tubes/secondary combustion chambers independent of the primary air supply in virtually all modern EPA stoves.  This ensures that there is always a supply of oxygen for secondary combustion.

OK - so how much does the density of oxygen at different temperatures contribute to oxygen supplied per unit volume of air?  This is a pretty important question since it seems to be the crux of your argument (argument is defined as "A fact or assertion offered as evidence that something is true" by the way).
Anyway, using the ideal gas law: PV= NkT
One mole at standard atmospheric pressure and room temperature will occupy 0.84945116885055 ft^3 of volume.
The same mole of air at a freezing temperature (say 32 degrees) will occupy 0.791497822860405 ft^3 of volume.  

So on that basis alone, there is about a 7% difference.  Now here is where some real testing would have to come into play.  What temperature does the cold intake air reach by the time it actually hits the firebox?  My guess is that it rapidly warms and expands.  And how does this minor difference in expansion affect draft?  Remember that as far as draft is concerned, we are talking about the air going from 32 to 1000 vs. 70 to 1000 degrees F.

My guess is that this makes no difference to the heating performance of the stove because you are going to adjust the air control to achieve the same burn rate with either stove.   But I will admit that at full air the stove with the cold air intake MIGHT burn SLIGHTLY hotter and faster (which also slightly increases your risk of overfiring the stove if you normally let it run at its max air setting).  I'd still love to see a controlled experiment though.  There are a lot of factors - for example maybe as the air expands as it goes from outside to inside it actually slows down the air intake, outside air might also contain a higher moisture content per unit volume, not sure how that might affect things, etc.  You also might not get as long a burn time at the MINIMUM air setting which could be more important to a stove owner than a potentially higher temperature burn at max air setting.

"I agree that chimney height has nothing to do with wind induced negative pressure. It is the height in relation to the peak of the roof. If it is lower the wind can blow over the roof and into the chimney IE “wind induced negative pressure”."

Sorry, you don't understand this problem at all.  We ARE NOT TALKING ABOUT WIND BLOWING DOWN THE CHIMNEY - not sure how many times this needs to be explained or how many different ways it can be explained... when wind blows against one side of your house, it creates positive pressure on that side, and negative pressure on THE OPPOSITE side of the house.  As a result, if your OAK intake is in this negative pressure zone, there is a force that wants to pull air down your chimney and out the OAK.  IT MAKES NO DIFFERENCE how high above your roof the chimney extends.  But again, since no one has produced documentation of home fires that resulted from this, I don't consider it a big risk factor, still it could be a factor that reduces draft at times, and possibly is a safety risk.  In the very least I would hope that people avoid installing an OAK intake on the side of their house opposite the prevailing wind.

Indoor air quality is my biggest concern.  You say you are getting plenty of ventilation in your house - but you also say you have positive pressure, so what exactly is drawing the air into your home?  I understand you have fan vents, but these are probably only running for a few minutes a day.  If there is really positive pressure, how is the air pulled into your home?


p.s.  They keep hospitals (well at least patient areas) cool because bacteria thrives in warm, moist environments.  It has nothing to do with oxygen density.  The difference in oxygen density from 68 to 72 degrees is negligible.

"The main reason hospitals are kept cold is that bacteria and germs tend to flourish more in warmer temperatures," says Lori Harris of the Desert Springs Hospital in Las Vegas, Nevada.  The temperature in the Desert Springs Hospital emergency and operating rooms is a brisk 68 degrees F (20 degrees C), whereas the lobby is a toastier 72 (22 degrees C).


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## Woodstove master

You are right about the misinformation. Sometimes I explain things wrong when I type / think too fast, not sure. Even though I understand how it works. Sorry.

I agree on the density also. It is a very little benefit if any. I just think the more the better for combustion, so it can only help. Well, just as we all agree colder air is more dense with oxygen. I know we all do as I read the entire post this afternoon. Enough said about that then. Correct, a controlled experiment would be awesome.

I do understand the "negative pressure on THE OPPOSITE side of the house" but I do still believe the height of the chimney in relation to the peak of the roof is important. It is required in New York to be 2ft above the peak. I will not repeat. But I wonder why it is required then? In my installation manual for the chimney (Simpson Duravent) there is actually a pictorial of the process of the wind accelerating over a roof peak and down the other side into the chimney. Maybe it is wrong? We could save a lot of money if chimneys were shorter. I wonder if this would happen without an OAK? If the chimney was below the peak...

Indoor air quality is my utmost importance also. You bring up a good point. I am not sure. I will have to look into that one, because now I am concerned.


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## stoveguy2esw

Woodstove master said:
			
		

> No, not exactly, but just because they build the stoves does not make them "experts". Scientific proof does. It does not mean they will tell you it is ok to modify your stove in any way. I know a lot of companies that you could say are "professionals" in their industry but are idiots. These wood stove companies statements are hugely based upon liability. This goes for most companies, especially these days with all the law suits. They will not give statements or directions on how to modify their stoves in any way as it will place all the liability on them for doing so if something goes wrong. This is why they sell "outside air kits" and explain to follow directions exactly or risk fire / injury / death. This does not mean that if we build our own kits that they are not safe. It does mean that if something went wrong it would not be the liability of the manufacturer due to not using approved setup / kit with the unit. The kit can cost $150 for some stoves. I made mine for $23 and is probably better / safer than what I saw in the store. The kit in the store that came directly from the manufacturer was a piece of junk, very flimsy, not sealed well. This would let sparks out if installed as they state. If a backdraft occurred.
> 
> I do believe that if the manufacturers could talk "off the record". They to have modified the stoves themselves to make them work better. The manufacturers are not going to go to the extra effort that I did to make sure my stove seals well, experts or not, it would cost too much money and profits would go down, designs would have to change. This is not to mention that if they go too far they are opening themselves up to further liability if the mods failed and or did not work correctly. The manufacturing process alone does not provide for adequate seal anyhow. Many more things would have to be done. Do the kits work? Yes. Do they work as good as they could? No. Same goes for everything else. There is always room for improvement in any design. Otherwise we would still have the model T. Yes I would modify it also.
> 
> The stove companies are wrong? maybe so, but not all of them. Do they back it with scientific proof, doubt it. At least not all of them. The FDA here in America is a complete and utter joke. They approve all kinds of chemicals in drinks and foods these days that are causing cancer and many other diseases and killing people. FDA is a big deal also. They to are looked at as "professionals" but they are wrong....



ive read your data , and have only one (yet glaring) item to take up with you. your description of stove manufacturers as "idiots" 

first off, i happen to be a stove manufacturer, and while im still quite a few credit hours short of a doctorate, i do not feel that i am an idiot, and im sure that if i polled the engineers we employ as well as the others in the industry (who im sure are pretty proud of the parchment they have festooning their office walls) would take exception as well. 

secondly, as for your statement about the industry professionals not giving you input on how to "modify" their stoves, they cannot do so as the units undergo testing for UL listing as well as EPA certification. the units must be built to the same specifications that the tested unit was built to in order to maintain that listing and certification. alteration of the unit , or modifications as you put it are illegal.

as for their OAK kits companies may very well have a kit that they offer, we at esw require outside intake air for all pellet stoves and multifuel stoves, for this reason we supply a kit with each unit , and supply directions for installations which may not fall within the parameters the kit can cover. 

as for making sure that your stove seals, i would expect it to do so in as far as what the design was intended to do, if not then its a deficiency that the manufacturer should correct. and im sure that would be dealt with should the situation warrant it.

also, the comparison to the model t was pretty disingenuous, modifying an automobile leaves the same liability, if you go out and drop a nitrous oxide system in your car then wrap it around a tree , do you really think the auto manufacturer will be found at fault? same deal with a woodstove, modify it and burn down your house, who foots the bill?

so, calling us idiots for trying to field a product and protect you from making a possibly dangerous "modification" to your stove by only advising parameters which the unit was tested and ul listed at makes us idiots...

i think you need to check your mirror                   idiot


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## tradergordo

Woodstove master said:
			
		

> I do understand the "negative pressure on THE OPPOSITE side of the house" but I do still believe the height of the chimney in relation to the peak of the roof is important. It is required in New York to be 2ft above the peak. I will not repeat. But I wonder why it is required then? In my installation manual for the chimney (Simpson Duravent) there is actually a pictorial of the process of the wind accelerating over a roof peak and down the other side into the chimney. Maybe it is wrong? We could save a lot of money if chimneys were shorter.



I think you misunderstood me.  The issue of flow reversal due to wind induced negative pressure zones (which can only affect installations with OAKs) has nothing to do with chimney height above the roof or wind blowing down the chimney but I NEVER said that wind blowing down a chimney could not also be another flow reversal / draft problem.  Code for chimney height above the roof is very important for any stove installation regardless of OAK use (but in fact if someone did have a poor chimney installation the whole wind down the chimney scenario could be much worse for the person using an OAK, especially if there are structures nearby which tend to cause these downdrafts on a routine basis).



			
				Woodstove master said:
			
		

> Indoor air quality is my utmost importance also. You bring up a good point. I am not sure. I will have to look into that one, because now I am concerned.



Well I certainly don't want to cause concern if it isn't warranted, but again this is precisely why a controlled study would be so valuable.  Without sophisticated equipment its impossible for an average person to monitor indoor air quality.  I think some day in the distant future such monitoring will be standard in "smart homes".


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## stoveguy2esw

ok, if thats the case i apologise, but its still a very uninformed view that the poster has placed out there.


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## Gooserider

Mike, I would agree with you about the stove makers not being "idiots" but I think there is a fair bit to be said about Woodstove master's statements about the industry's reluctance to say anything outside the manuals - sometimes I think it's liability related, sometimes it may be profit driven...  

Some things like OAKs are fairly straightforward items - I am sure that a company could publish minimum specs on what would make a safe OAK - what to use for the tubing, type of fittings, etc. - as opposed to selling a kit for $150, that probably cost them under $10 in parts.  Is the primary concern liability, or protecting profit margins?  (IMHO Nothing wrong w/ making a profit BTW, but sometimes seems like prices cross the line between profit and gouge...)

Many stove manuals talk about hearth protection, and say "material X or equivalent" - but won't tell you what "equivalent" is, even to the extent of saying what R-value would be acceptable, or giving a common material to reference - i.e. 1/2" Durock...  I'm SURE they have some idea, and this is one I can't even see how you'd be violating a listing or exposing yourselves to liability to tell us... (especially if you erred on the conservative side in the comparison)

I've also seen MANY statements from industry folks, or others in a position to know, that stoves are "tuned" to produce optimum results in the burn lab, doing the EPA burn tests.  Also that in many cases the controls are simplified to "idiot proof" the operation for the benefit of the "clueless user" - Granted it doesn't come direct from the car makers, but there is lots of knowhow out there on how to retune our cars for optimum driving performance, so why can't we re-tune our stoves?  Would there be benefit in being able to adjust some of the air controls in response to wood type?  What about adding a way to fully shut off primary and secondary air in case of chimney fire / runaway stove? What about attempting to retrofit a thermostatic control to a stove that didn't come with one?  IOW, there are lots of potential mods that many of us (who at least like to think we're clueful) would like to try

Even something potentially simple and I would suspect unlikely to affect listings, like replacing the legs on a Hearthstone Mansfield (Nice stove, except many don't like the "duck feet") we are told "don't even think of it" as opposed to "This is the spec on the leg, we aren't liable for what you do with it"

So I'm not calling you idiots, but I'm grouched about the information you hold back on us - even though I understand why you do...  (I would love to change the rules on liability for such advice, IMHO there shouldn't be any)

BTW, this isn't specifically directed at you personally or Englander as such, you just catch it in your role as "representative member of the industry" 

Gooserider


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## BrotherBart

I am just sitting here wondering about a nitrous set up for the 30-NC. Hmmm...

Now that would be some major secondary burn.


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## Gooserider

BrotherBart said:
			
		

> I am just sitting here wondering about a nitrous set up for the 30-NC. Hmmm...
> 
> Now that would be some major secondary burn.



Nah...  Go for the spray mist LOX injectors.....  If it's good enough for NASA, it should be good enough for the stove!   

Gooserider


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## Woodstove master

First of all I want to state that it is never my intention to get anyone angry at me and appologise if I did. I was not talking about wood stove manufacturers, but yes industry in general. I Have not dealt with stove manufacturers much but have dealt with many other industry manufacturers where I meant they can sometimes be "idiots". 

My God Mother had a Cadillac Katera and had the car in the shop 16 times over a two year period between New York and florida. She barely drove the car. This went as far as fighting the manufacturer / district management of several areas to rectify the problem. The answer from the top was that "she does not drive the car far enough daily to charge the battery". The car would not start at home and had all kinds of crazy electrical problems. She regularly drove less then a mile a day to the grocery store. When the manufacturer could not fix the car I was asked by family to look at it. I have two years in electrical engineering of robotics. I was a little reluctant as to the complexity of new cars today. In knowing sometimes even the experts look over the simple stuff, decided to take a look. Within one minute of opening the hood I found the problem. I lifted the fireproof shroud from around the battery and found a burned up positive wire coming from the alternator going to the battery. Wherever it touched the side of the battery was burned up, you could see it was shorting out the cells. I called the district manager and advised him. He is one of their top mechanics / representative for the north east region. He was unsure that was the problem. I was floored! I told him that the cable was run under the fireproof shroud making it too close to the battery and shorting out the cells. If he replaced the battery and the cable and it did not fix the car, I would pay for all of it. This repair was made and the car has never had a problem since in 3 years.
I also found a manufacturing defect in 1/2 our new ambulances and had to repair it myself as FORD could not find out what was wrong with the electrical system after 6 months. 

I know this is off the subject but I am just trying to prove a point on where my statement came from. Sorry if I misled anyone.


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