Outside Air Kit in non-airtight house. Does it make a difference?

[danielsonrose]

Just how cold is this outside air going to be by the time it gets into the firebox ?

Is everyone running nitrogen cooled tubes ?


The condensation running off the tubes must be ruining everyone's floors.

I've made it a habit of feeling my tube (OMG!) for temperature when it is really cold out just to verify that I am sucking cold outside air and that it really is working. The tube is always colder than room air but never cold enough to condense water. Probably due to the 25% RH in the stove room. The single pane windows seem to be much colder and easily collect condenstion in adjacent rooms.

To be honest, I feel the chimney pipe too for heat so I am a tube feeling fool.

Mine condensates. I ran steel vent pipe and when it is under 20 out it will condensate. Recently it was in the single digits and frost formed on the first foot of pipe.

 

[northcountry]

I think the value of this debate is the prospect of a Mythbuster episode, as Rocky suggests.

If it were me, I would base my decision solely on whether or not I noticed an uncomfortable draft when the stove was burning.
If not, don't bother. If so, maybe it's worth doing.

Otherwise, the difference is in the margins and probably not worth much more than the interesting, but ultimately academic exercise we see here.

 

[North of 60]

I like to control where my -30 to - 50C air is coming in the house during the winter. As long as your fresh air duct is insulated the condensation is at a minimum.

 

[carpniels]

Hi Guys,

I added an OAK to my Quadrafire Isle Royale. Mostly after doing research and emailing Tom from chimneysweep a few times. The install was not too difficult and is a 2 ft galvanized steel straight run from behind the stove.

The biggest difference I noticed was that the stove runs hotter. I run it mostly between 600 and 800 without issues. Temps go up fast after refueling. Fire lasts as long as before. I also had the first ft frost up when the temp is below 0 outside. The biggest difference I noticed is that the far away rooms (bedrooms) are not nearly as cold as they used to be. I used to be able to feel the cold outside air rush in but now I don't feel any draft around the windows anymore. It seems that the combustion air is not drawn in through the cracks of the windows and therefore room temps stay higher.

So far, I have been very pleased. Just a few comments:
1) I cannot install the blower on the IR and the OAK at the same time. I will have to bend the AOK pipe a little to make room for the blower. I cannot do that until the stove is completely off in April.
2) The AOK pipe is shoved into the hole in the back of the stove. I don't know how to attach it properly.
3) I don't see how I can insulate the AOK pipe as it is so close to the stove, it will heat the insulation and probably set it on fire.

Thanks

Carpniels.

PS. So if you ask me, install it. It works

 

[hvcompton]

I’ve been building, dyno-ing and racing drag motors for almost 30 years and I can assure you that lean motors do not make more power and that once you get into the 300bhp/litre range with 15:1 mixture you will end up punching a hole through a piston in as little as 5 cycles.

True but that does not really have anything to do with what I said. Drag engines have very high compression. The higher the compression the higher the need for fuel. Many other engine builders do not need the 13.7 to one fuel ratio for an engine with 14:1 compression would need. Most engine builders feel that 14.7 to one is ideal.

Anyone need some info on engines check out this guys book he is awesome. Have you calculator ready.
Four-Stroke Performance Tuning in Theory and Practice
Bell, A. Graham

Where do you race I follow most of the drag racing in the states? Do they have drag strips in Spain?

 

[begreen]

Maybe better topic for http://dragplace.com/ ?

 

[Todd]

Ok, here is another question about OAK. How long of a run of pipe can you use? In my situation, my stove is in the basement and I would have to run an OAK across the bottom wall then up and out through the wall just above the sill plate, (about 18' total). And then there would be a few 90 degree bends. Would this effect the air flow? Is there a recommended max length?

 

[mtnxtreme]

Should the OAK pipe be insulated and if so , with what?

 

[bokehman]

Ok, here is another question about OAK. How long of a run of pipe can you use? In my situation, my stove is in the basement and I would have to run an OAK across the bottom wall then up and out through the wall just above the sill plate, (about 18' total). And then there would be a few 90 degree bends. Would this effect the air flow? Is there a recommended max length?

I don't know about maximum length but every time you double the pipe length you quarter the flow. For your air supply to work properly it needs to be able to easily flow as much as a wide open primary demands. If you are worried that your run is too long increase the diameter (there must be a recommendation somewhere).

 

[Todd]

Well I hooked up 18' of aluminum dryer vent and cold air is pouring out of it near the stove air supply. Seems like it will work since the supply is higher than the stove. Kind of like a siphon. Now I just need the stove adapter.

 

[Highbeam]

18' is long but if you used 4" pipe then I've got to think you have a good chance of success. Once you get the adapter you can verify adequate air by hooking and unhooking the pipe and looking for change. I couldn't find a length requirement on my HS. Amazing how air just flows out of the OAK. It wants to feed your stove.

No need to insulate the pipe. It is not a cold air intake like on a car. I would only insulate if condenstation became a water problem like on a metal roof in a barn. The temperature of the combustion air is of no importance to the stove.

 

[Galroc]

One thing I need to mention is most have other appliances that need air, like a furnace or a stove vent.

In my case, I have an oil furnace. I also have a 1200CFM hood vent that will dwarf anything a pellet stove can do, which I think is about 10cfm max.

So, I think I will go with an outside air kit for my pellet stove so that it isn't affected by our stove vent, even if it already has a source for outside air.

Ok, my Mt. Vernon AE is installed with an OAK. I went through the rear of the fireplace and that wasn't easy. I used some masonry bits and an air power chisel, which made short work of the brick. The total length is about 2 feet.

After running the Mt. Vernon AE, I have to say the OAK is worth it. I stated above that the stove will need 10cfm for combustion, but what I didn't know was that the stove pulls air through the combustion chamber. I guess this is how pellet stoves work, they basically fan the fire

Anyway, it looks like the stove is pulling in much more than 10 cfm. I don't know how much, but I am glad that it is pulling it through the OAK instead of creating a draft in my house.

 

[rmcfall]

I've had Outside Air Kits on two stoves--a Waterford Ashling and a Woodstock Keystone (my current stove). The OAK on my Ashling seemed to seal pretty tightly against the stove, whereas on my Keystone it more or less hangs against the back of the stove without making a tight seal. I any case, I've never had any problem with burning either of these stoves and I don't notice any air being pulled through windows, etc. Of course, I put in the OAK's from day one, so I don't have anything with which to compare. However, I can say for certain that I haven't had any problems. I figured that if I could burn outdoor air instead of indoor air, then why not....and if I reduce the drafts then that's all the better...

 

[Woodrat]

-- Isn' t all the incoming air for combustion in newer stoves being preheated to a pretty high temperature anyway??? Doesn' t seem that drawing the air from outside could lower the temp very much by the time it reaches the inside of the stove.

Woodrat

 

[kjklosek]

Just how cold is this outside air going to be by the time it gets into the firebox ?

Is everyone running nitrogen cooled tubes ?


The condensation running off the tubes must be ruining everyone's floors.

I've made it a habit of feeling my tube (OMG!) for temperature when it is really cold out just to verify that I am sucking cold outside air and that it really is working. The tube is always colder than room air but never cold enough to condense water. Probably due to the 25% RH in the stove room. The single pane windows seem to be much colder and easily collect condenstion in adjacent rooms.

To be honest, I feel the chimney pipe too for heat so I am a tube feeling fool.

Jeezes man. Didn't your mom tell you that if you play with your tube too much you'll go blind!

Lay off that sucker.

J.P.

 

[Rick]

Could be a nice, new accessory; a "Tube Sock". Keeps your tube warm to cut down on condensation. A must for every OAK. Available in fashionable colors to match every decor.

 

[stoveguy2esw]

a couple years ago i did play with this a bit just to play , i installed a pellet stove (just easier to see differences for me) in a room at the plant which i could control the ambient air pressure in the room and adjust it mechanically using vents that would seal very tightly and an exhaust blower with a rheostat to adjust its speed , also had means to monitor the pressure in the room. the unit ran without any difficulty and whnen i unplugged it to simulate power failure there was little if any smoke spillage through the primary or airwash intakes. note that an OAK was not installed.

as i sealed the room up incrementally the stove performance did not really fall off that much but the "lost power" test did produce more spillage than at equal pressure, though still not much. as i increased the negative pressure in the room the stove performance steadily worsened and power off smoke spillage increased along the same lines. here's the kicker though at ambient pressure the room temps were a bit lower , as i sealed the room more tightly the temps came up a bit , then started falling as performance fell of with the stove (this when i started to drop pressure with the blower) after taking all this in , i installed the OAK kit and repeated the tests. the results were suprising. the unit did not fall off with the sealed room , nor did it when i dropped room pressure, and only when i had the blower i was using to drop pressure in the room maxed out did the stove spill any smoke in the power off test , this was a very minor loss through the airwash intake.

granted my little test wasnt exactly a cutting edge scientific experiment , but the simulations i used did show that the units performance was effected by a simulated "tight house" situation , and was drastically effected by negative pressure along with the tight house situation. however the OAK kit battery of tests showed that the unit was virtually unfazed by the same conditions.

it made me a believer at least when it comes to pellet stoves, if Tmonters numbers are correct , and 105 cf of air is needed to combust a pound of wood, (pellets mind you, are denser than cordwood) a pellet stove capable of burning 5 lbs per hour would use 525 cf of air an hour at that rate (probably more) that would mean that a 10X10X8 room would be evacuated of 65% of the air present at start by 1 hours use of the unit burning at that rate (though i realize that the size of the room is small im not a math major keeping it simple , but the formula should hold true) this air would have to be replaced within the room for the unit to perform at peak, that means that air will leak in this will reduce the ambient temperature of the room , requiring more btu's to be used to compensate. in my opinion this amount of btu's would be higher than what would be needed to raise outside combustion air to the level of heat needed for combustion in the unit. throw in also the lessened possibility of smoke intrusion into the dwelling during a power outage or malfunction, and there you have it , installing an OAK kit should would not worsen performance in any case , but it could greatly improve it in many cases.

 

[stoveguy2esw]

Just for completeness, here are some references about the use of outside air. It appears that John Gulland, founder(?) of the web site http://www.woodheat.org, is one of the leading proponents of NOT using outside air. This seems to be based on a study done for the Canada Mortgage and Housing Corporation in 1989 called Fireplace Air Requirements (http://mha-net.org/msb/docs/airreq.PDF). The findings in this study resulted in the removal of the outside air requirement from the Canadian building code in 1995.

A few other references:

John Gulland blog writings: http://mha-net.org/msb/docs/outsair.htm
Woodheat discussion of outside air: (broken link removed to http://www.woodheat.org/outdoorair/outdoorair.htm)
The positive case for using outside air: (broken link removed to http://www.chimneysweeponline.com/hooa.htm) and (broken link removed to http://www.chimneysweeponline.com/hooa3.htm)
Canada's A Guide to Residential Wood Heating: http://www.canren.gc.ca/prod_serv/index.asp?CaId=103&PgId=576 (see Chapter 10)

The CMHC study is almost 20 years old, and I haven't seen any references to additional, newer studies. The Chimney Sweep Online articles look like good arguments for using outside air. That said, I would not use outside air unless 1) it was cheap and easy to install, which it isn't in my case, or 2) I was having a performance problem that could be solved by outside air.

i just re-read this (broken link removed to http://www.woodheat.org/outdoorair/outdoorairmyth.htm) it deals with fireplaces with glass doors, some of its conclusions are acceptable when dealing with them , but not woodstoves, its not concise , the arguements against outside air (pardon the pun) dont hold water. passive outside air (not directly connected to your unit) isnt recommended in this article , but in the main page article dealing with depressurization during starting a fire it suggests opening a window (isnt that passive outside air??) also , the drawing dealing with high wind downdrafting suggests that proper flue installation doesnt protect against the problem unless outside air is not equipped , suggesting that if inspection shows soot on the intake that the intake should be blocked or disconnected(which will allow that soot into the dwelling instead of being carried outside through the intake , just what i want , smoke in my house on windy days) finally when addressing draft hoods for ranges and other appliances which remove air from the dwelling it states that these can be controlled (true but does that mean i have to dump a bucket of water on my fire before i can cook dinner or dry a load of clothes?) these conclusions are based on poorly installed systems , likely outdated ones looking at when it was written, i wouldnt think of sending a customer of mine to read this garbage. its just terrible


OTOH the chimneysweepsonline article and supporting arguements seem to mirror my thoughts i read it after i finished my rebuttal to the woodheat.org articles. this site on the other hand i would recommend reading , not only does it explain the positive virtues of OA it lists and rebuts the opinions of the other site. very well done site

 

[Todd]

Just to give my .02. I installed an OAK on my Fireview about a week ago and have noticed a difference. It seems to me that in a basement install it does help, especially if the stove has to compete with other appliances like water heater, clothes dryer, and bath fan. I use to get a little smoke spillage on low burns when the dryer and water heater turned on, not any more. It also seems to just put out more heat. My house is warmer by a couple degrees and there is less cold drafts as far as I can tell. This is a totaly unscientific study, but it works for me.

 

[rmcfall]

Just out of curiosity, does the OAK for the Fireview make a seal against the stove, or does it more or less hang against the stove and have an opening for the air control lever? I suppose that in either case the majority of the air will be drawn from the outside since that path would be the least resistant....

Just to give my .02. I installed an OAK on my Fireview about a week ago and have noticed a difference. It seems to me that in a basement install it does help, especially if the stove has to compete with other appliances like water heater, clothes dryer, and bath fan. I use to get a little smoke spillage on low burns when the dryer and water heater turned on, not any more. It also seems to just put out more heat. My house is warmer by a couple degrees and there is less cold drafts as far as I can tell. This is a totaly unscientific study, but it works for me.

 

[stoveguy2esw]

Just to give my .02. I installed an OAK on my Fireview about a week ago and have noticed a difference. It seems to me that in a basement install it does help, especially if the stove has to compete with other appliances like water heater, clothes dryer, and bath fan. I use to get a little smoke spillage on low burns when the dryer and water heater turned on, not any more. It also seems to just put out more heat. My house is warmer by a couple degrees and there is less cold drafts as far as I can tell. This is a totaly unscientific study, but it works for me.

a basement install would gain even more from OA than an upper floor due to being below the zero pressure plane. as for more heat that woodstock is a honey , it should heat well, the difference is likely the 500 cf an hour of cold air that you are no longer pulling in from outside you arent having to waste btu's heating that air so your temps are up even though the stove it self might not even be actually burning hotter. good to see you are benifiting from the install, nice post

 

[Todd]

No, it doesn't make a tight seal, and I was worried about that but I put a lit match next to the opening by the air intake lever and the flame pushed away not into the intake. I'm thinking because the supply is higher than the stove it keeps a possitive pressure into the stove intake.

Just out of curiosity, does the OAK for the Fireview make a seal against the stove, or does it more or less hang against the stove and have an opening for the air control lever? I suppose that in either case the majority of the air will be drawn from the outside since that path would be the least resistant....

Just to give my .02. I installed an OAK on my Fireview about a week ago and have noticed a difference. It seems to me that in a basement install it does help, especially if the stove has to compete with other appliances like water heater, clothes dryer, and bath fan. I use to get a little smoke spillage on low burns when the dryer and water heater turned on, not any more. It also seems to just put out more heat. My house is warmer by a couple degrees and there is less cold drafts as far as I can tell. This is a totaly unscientific study, but it works for me.

 

[Todd]

Just to give my .02. I installed an OAK on my Fireview about a week ago and have noticed a difference. It seems to me that in a basement install it does help, especially if the stove has to compete with other appliances like water heater, clothes dryer, and bath fan. I use to get a little smoke spillage on low burns when the dryer and water heater turned on, not any more. It also seems to just put out more heat. My house is warmer by a couple degrees and there is less cold drafts as far as I can tell. This is a totaly unscientific study, but it works for me.

a basement install would gain even more from OA than an upper floor due to being below the zero pressure plane. as for more heat that woodstock is a honey , it should heat well, the difference is likely the 500 cf an hour of cold air that you are no longer pulling in from outside you arent having to waste btu's heating that air so your temps are up even though the stove it self might not even be actually burning hotter. good to see you are benifiting from the install, nice post

Yep, that makes sence. I haven't even been using my little fans to help circulate the heat. I'm keeping a 5 degree difference between the basement and main floor even in below zero weather. Wish I would of done this sooner.

 

[MishMouse]

I put an adhoc OAK into my pre-fab home on Wednesday.
Opened hole in the plastic that I covered a window with, slightly opened the window, and placed the end of a 20ft long 4in dryer vent into it and resealed it, then snaked the vent near the stove.

I had a major improvement in my stove temps, normally my highs would be around 500-550, now I can get it up to 650-700 and above if I don't keep an eye on it. When the stove is running you can feel the air being pulled out of the vent, when it is off very little if any. I also noticed that the upstairs does not have as many drafts as it had before when I was running the stove.

The other night just for grins, I sealed the vent off, within 10-15 mins the stove dropped from 600 back down to the upper 400's.
I have a 8ft high block basement, with major negative pressure problems.

So depending on your situation and especially if you have your stove in the basement I would recommend an OAK.

 

[please302]

To all of those who are quick to give an opinion about outside air kits please be weary. I have read a lot of negative comments about oak and how they dont work or matter. However, I had just recently bought a p68 and had it installed on dec 1. The stove was installed downstairs in the finished basement of a dutch colonial house with the finished basement, 1st and 2nd floor with center stairs for both floors. The house was built in 1951 with updated windows and I just stuffed the attic with insulation this past spring. The house is not noticeably drafty. Anyways, at the time of the install the installers who have been a family wood stove/pellet business for years talked me out of the oak. For me it was not the money but rather the way they had explained it’s terrible looks (a dryer vent pipe next to the exhaust pipe) and the supposed “facts” that they gave me about how it would not be a great benefit as everyone makes them out to be. I was wondering at first who he was talking about when he mentioned “everyone? The blogs, the manufacturer? The installers stated that the only reason that they use them is for clearence purposes on the install. They stated that although there is better efficiency obtained by the stove and it is easier to get it cleared during inspection ( hummmm, safety?) that the benefits are hardly recognizable. So I said ok, thinking that if I decided later to install one I could just do it myself since it is the same as installing an dryer vent and it would be cheaper if I did the work opposed to a pro installer. So I began to use my stove which was great in every way. The heat was great and maintenance was a breeze. I didnt have any of the problems that I had read everyone talking about on this website even though I was worried about the PENNINGTON PELLETS that I had bought before I saw what a fiasco that they had been the year before. ohh by the way I just noticed when I poured some pellets into the hopper that there was a 5” piece of wood chunk in the bag of PENNINGTON PELLETS but thats another story for me and PENNINGTON to duke it out. Anyways, the stove was great but as time went on approx. 2 weeks I did notice a “draft” near my feet downstairs where the stove was installed. I also noticed drafts on both sets of stairs and noticed that upstairs was not getting warm and figured that it was just too far away from the stove. I also figured that the “draft” was actually the cold air dropping and the hot air rising and displacing the cold air. I was surprised about the strength of the draft on both stairs however. It was just more then I expected but maybe it was normal, how do I know. So after 2 months of constantly using the stove for the main heat source I began to think with every cold draft that I felt whether the oak would matter in my house. I finally decided to install it myself about one week ago and it was actually pretty easy, taking only a few hours of drilling,caulking and fitting. After I was done I turned it on and got ready to compare the results with and without the outside air kit since I had used the stove for a month and had a good idea of what it was capable of. The results were so drastic that i noticed them right away. The “drafts” on the stairs were greatly diminished and the heat of the stove spread upstairs much quicker and heated even the 2nd floor which it had not done before. The heat from the stove was greater which was obvious. I had the heat on 3 and 1/2 and the fire was still huge and it heated the 2nd floor on a 20 degree night to 71 degrees. In the past even with the heat cranked up to 6 I could not get it over 68. I honestly believe and now have, although not scientific, some obvious evidence that in my case the oak made a hugh difference in heat output, efficency, increase in heat radiation and travel throughout the house in areas where I could never feel the heat before. I do think that air is allowed now to move more freely and farther into the house and so areas are able to heat up that never use to get heat and areas that did get heat are hotter. I am not sure if it has something to do with the resistence that is being overcome by having the oak but the difference is undeniable. SO to all of those with opinions that seem to make sense, there are a lot of factors that end up influencing the final outcome which in my case speaks for itself. And to all of those who are questioning whether or not to put an oak in their home I would just tell you to look at my results and look at their own particular situation and decide. Good luck.