fresh air kit

[TreeCo]

t.

i got links below worth reading. nice to see a logical,though seemingly adversarial, perspective.[/quote]

Sorry about the adversarial perspective. I think it comes from reading so much bunk on the subject of outside air over the years!



For instance, the post just after yours claiming that cold air is better for a wood stove combustion because it is denser and therefore contains more oxygen.

Thanks for the links. I'll take a look at them.

 

[DAKSY]

I have installed in my finished basement a TL 300 Harman wood stove. I am a new wood burner and trying to do everything correct. If it was not for this forum and everybody's help I would be lost. Being a first year burner I am always doing some research and probably will never stop.

My question? Why a fresh air kit? What does it do? How can you tell if you need one?

My stove is capable of having one and was suggested. Looking for thers opinions..

Go here for your answers:

(broken link removed to http://www.woodheat.org/outdoorair/outdoorair.htm)

 

[mike1234]

I do not understand the big deal about having an air supply for your fire. Can it hurt? There is no drawback that I can see.
We could try burning that oxygen impregnated wood in an environment without another air supply, if it's 1/2 air it would burn fine right?
How about this, we'll get 2 people in a room without air, I get an air intake to breath through, we'll throw the other person some firewood to breath.
What do you do if you have a chimney fire? Call 911. OK besides that, try to starve it of.....
We all know fire needs air, so give it a supply.
Seems like that makes sense to me, but I voted for a Bush, 3 times.

 

[chrisfallis]

Fresh air is not needed. It is a myth!


The only way a wood stove can use up the oxygen in a house is if it has caught the interior of the house on fire!

I could not operate my stove properly to maintain a comfortable house without an OAK. Humidity also plays a big factor in my climate. I suggest you do a search on this subject. Its certainly not a myth. Argumentative yes, but not a myth. Depending on your climate.

I have to agree. We live in a 110 year old house that is anything but airtight. In the basement our natural gas furnace dumps into a 12 inch flue and we have a pretty steady stream of air going up the chimney all heating season. Ther is a big "draft inducer" collar around the metal chimney pipe between the furnace and the brick chimney. I think the purpose is to keep large volumes of air going up the stack. It does this in spades. Last year I didn't replace a door weatherstrip on our back door after we installed some new flooring. I can close the kitchen door and isolate this leaky door and basement steps from the rest of the house. That space is always significantly colder than the kitchen. From a total energy perspective, I know that I am heating air and pushing it up the chimney and it shouldn't matter if I brought in outside air to the basement or if that air came in from around leaky doors or windows. From a comfort perspective, though, I would rather have cold outside air coming into my furnace room rather than in every single window.

She Who Must Be Obeyed was lying on the couch last night next to 3 of our leaky windows and noted with some dismay that the 13 degree F. draft on the back of her neck was not pleasant. No joke.

 

[PeteD]

Sorry about the adversarial perspective. I think it comes from reading so much bunk on the subject of outside air over the years!



For instance, the post just after yours claiming that cold air is better for a wood stove combustion because it is denser and therefore contains more oxygen.

Thanks for the links. I'll take a look at them.

Well, let's hear you debunk it, instead of just lobbing bombs. I have an open mind. I bet people with OAKs will not tell you their stove does not get hot with an OAK. I believe the COLD, DRY air coming is going to create a hotter fire, which will at least offset the cooler air temp coming in and in the end radiate more heat to the room, when combined with the fact that you are not sucking heat out of the room and in through cracks in the house.

My post was in response to yours about the OAK making the stove cooler and possibly decreasing combustion efficiency. I would like to see the evidence that an OAK cools the stove and fire. I do not buy that for a second.

I am not stating that is the purpose of the OAK. The purpose is simply to not suck indoor air up and out chimney.

For the record, I hated thermodynamics in college, but I did pass it (barely). The heat capacity of air is not an area I want to get into. But humid air is going to have more heat capacity than dry air at a given temperature (take more energy to warm it up). Cooler dry air (to some point a thermo engineer can calculate for us sometime) will take less energy to warm up than warmer more humid air. What is this temperature difference is for 60% indoor relative humidity versus 5% outdoor relative humidity, I don't know. Like I said, I hated thermo.

Pete

 

[Hogwildz]

Sorry about the adversarial perspective. I think it comes from reading so much bunk on the subject of outside air over the years!



For instance, the post just after yours claiming that cold air is better for a wood stove combustion because it is denser and therefore contains more oxygen.

Thanks for the links. I'll take a look at them.

Well, let's hear you debunk it, instead of just lobbing bombs. I have an open mind. I bet people with OAKs will not tell you their stove does not get hot with an OAK. I believe the COLD, DRY air coming is going to create a hotter fire, which will at least offset the cooler air temp coming in and in the end radiate more heat to the room, when combined with the fact that you are not sucking heat out of the room and in through cracks in the house.

My post was in response to yours about the OAK making the stove cooler and possibly decreasing combustion efficiency. I would like to see the evidence that an OAK cools the stove and fire. I do not buy that for a second.

I am not stating that is the purpose of the OAK. The purpose is simply to not suck indoor air up and out chimney.

For the record, I hated thermodynamics in college, but I did pass it (barely). The heat capacity of air is not an area I want to get into. But humid air is going to have more heat capacity than dry air at a given temperature (take more energy to warm it up). Cooler dry air (to some point a thermo engineer can calculate for us sometime) will take less energy to warm up than warmer more humid air. What is this temperature difference is for 60% indoor relative humidity versus 5% outdoor relative humidity, I don't know. Like I said, I hated thermo.

Pete

Pete,
your right in theory, but a turbo or supercharger lets say a charge air cooler on a semi truck, has a turbo &/ or a supercharger pressurizing the cooled air prior basically forcing it into the air intake.
A stove does not do this. I may be wrong, but a stove is going to use the same amount of cf, ci what have you of air whether its from inside or outside the home, it is merely taking what it needs and there is no supercharger or turbo forcing the colder air into the stove.
It is not pressurized as in a vehicle.

If a person wants an AOK, I say go for it. My installation on an interior fireplace made for a big PITA to add an OAK, so I went without. I have no noticeable draft issues or fire or draft problems. Code does play a role in some municipalities, and that should be checked first, also mobile homes call for OAK also.
The only issue I have researched on OAK is 2 issues, that don't necessarily apply to all installations.
One being as described, your taking cold air and cooling the firebox off, how much & how bad? Who knows, didn't find a study on it.
Second, is wind draft caused by certain winds related to the location of the OAK where it exits the home. I have read, (and just that, read), that under certain circumstances, the wind can actually draw air from the OAK father than introduce it in.
As with all stoves installs, you should research, then apply to your certain install & setup, if you feel you want or need it, then do install it. If you feel you don't and it is ok by local codes, then forgo it.
No one setup is the template for all installs. Other things to consider is if you have other appliances such as gas hot water heater, dryer, etc that the stove will be competing for air inside the home.
I have none of those and my situation worked out good for me without. Yours may be same or different.
Everyone has a personal opinion, you need to decide what is best for you & your set up.

 

[PeteD]

Hogwildz, I agree with pretty much everything you said. I realize you are pressurizing on a vehicle also, but there will still be more oxygen per cf in colder air. But that is really way off topic anyway.

My owners manual did mention installing the OAK vent away from windy areas.

The other issue is that 80 F and 10 F are both relatively "cold" air to a fire that is burning much hotter. I think we need to avoid treating air like it has the heat capacity of water - everyone knows how your water is harder to warm up in the winter. I have never seen a blacksmith quench his work in air....

I am not trying to say I have all the answers on this one - not even close. I enjoy learning through the discussion and research it brings.

Pete

 

[LLigetfa]

I may be wrong, but a stove is going to use the same amount of cf, ci what have you of air whether its from inside or outside the home, it is merely taking what it needs and there is no supercharger or turbo forcing the colder air into the stove.
It is not pressurized as in a vehicle.

A stove doesn't take only what it needs. It has no smarts. It takes what you let it. For a given intake setting, the denser outside air at higher pressure than the heated indoor air aspirates the stove better. Crack a widow an inch near the stove and feel the pressure of the air rushing in. That is how much more pressure you have with an OAK supercharging the stove.

There is hardly ever a downside to having an OAK. If you don't burn all the time the OAK can and will still draw in cold air, cooling the stove which in turn cools the room. Occasional wood burners would want to have a way to completely close off the air. If I don't burn in very cold weather, frost will form on the glass and the metal by the air wash grate.

The possibility of an OAK backdrafting however remote, should be factored in how it is installed. One should consider non combustible material with clearances and should introduce a sag that acts like a P-trap in plumbing if the intake is higher than the stove. In areas where buildings are close enough to introduce low pressure zones from wind induced vortexes the location of the OAK should be well planned.

 

[Hogwildz]

I may be wrong, but a stove is going to use the same amount of cf, ci what have you of air whether its from inside or outside the home, it is merely taking what it needs and there is no supercharger or turbo forcing the colder air into the stove.
It is not pressurized as in a vehicle.

A stove doesn't take only what it needs. It has no smarts. It takes what you let it. For a given intake setting, the denser outside air at higher pressure than the heated indoor air aspirates the stove better. Crack a widow an inch near the stove and feel the pressure of the air rushing in. That is how much more pressure you have with an OAK supercharging the stove.

There is hardly ever a downside to having an OAK. If you don't burn all the time the OAK can and will still draw in cold air, cooling the stove which in turn cools the room. Occasional wood burners would want to have a way to completely close off the air. If I don't burn in very cold weather, frost will form on the glass and the metal by the air wash grate.

The possibility of an OAK backdrafting however remote, should be factored in how it is installed. One should consider non combustible material with clearances and should introduce a sag that acts like a P-trap in plumbing if the intake is higher than the stove. In areas where buildings are close enough to introduce low pressure zones from wind induced vortexes the location of the OAK should be well planned.

Let me reword, a stove takes what it can with what you have the air intake lever, arm etc set at. In the case of Summit owners, it adjusts its own intake at certain temps with the EBT. So while it does not have a brain or smarts, it does have EBT which opens & closes to take in more or less air as it is designed to. Other stoves have a similar type bimetal disc for same purpose, others don't. I don't know that I would use aspirates to describe, as a strove does not breath, but the stack does draft more & less depending on outside temps & stack temps etc. But hey, if trying to use fancy words makes you feel smarter, knock yourself out. If a chimney, flue stack whatever you choose to call it drafts well, the load burns well, and everything flows well. If the draft is poor, then OAK, no OAK, whatever its, still going to draft poor & burn poorly. Honestly, when I open the back door to grab some more splits to add in the insert, there is no rush of air any more then if the stove is not running. Now of course is the stove door is open and then I open the door, yes it can create a draft that can be noticed.
As I stated earlier, its a matter of each persons preferences, their home & set up. I prefer to let folks make their own decisions, let them weigh the benefits for their situation, and come to their own conclusion.
As far as the hardly ever downsides you stated, I already addressed those, my apologies if I did not fill it with superior sounding words. But the meaning was the same. I wonder, what tools does one use to find low pressure zones & vortexes prior to planning? Ugg Ugg Ugg

 

[LLigetfa]

If by fancy words you mean aspirates and vortexes, well... you made the comparison to engines and "naturally aspirated" is a common term there. As for vortexes, swirls of leaves collect in them on the leeward side of a building. Modern gas furnaces have delicate pressure sensors that can shut down a furnace if/when there is even a small pressure differential between intake and exhaust. I don't know if they use fancy instruments or just SWAG it. I was given some hints by my installer when I was building my home, what to watch out for. Gas furnaces have both vents within a couple of feet of each other. Not so with wood stoves.

 

[Ivy Frank]

"If a house does not have the EPA suggested air exchange ratio........an outdoor air supply is not the answer! It actuality leads to fewer air exchanges per day....and results in higher indoor air pollution levels! Combined with a small amount of wood smoke spillage that even an expert user experiences from loading, etc., it makes OAS’s look even worse.
Frank can you point us to some research that backs up your opinion? "

I don't believe the government has funded research into outside air feeds, and I can't imagine any private entity would sponsor such inquiry.

But that, as I'm sure you know, is not dispositive.

Your stove is not an air exchanger. If you have air exchange issues, then you should get an air exchanger - a wood stove would not serve the function in late April.

Here's a quote from the link you provided: "ASHRAE also notes that "dwellings with tight enclosures may require supplemental ventilation supply for fuel-burning appliances, including fireplaces and mechanically exhausted appliances."

Whoops. Looks like you supplied a cite that tells us to add an OAK if we have a tight house.

Thanks for the corroboration.

 

[Firestone]

Greetings: I wood {got that pun ? } like to suggest that readers go to "Woodheat.org" for good info on this topic and the references to Canada Mortgage and Housing studies on this issue. There are three places on the site that discuss this, very good info. Now that I have mastered the process of posting photos, here is one of my outside air supply installation. I went to the local building supply place and purchased two 5 foot lengths of heat ducting which is used for under kitchen base cabinet installs. These two pieces snap together, and form a rectangular duct 3 1/2 inches by 10 inches wide. Before assembling the duct, I ripped a piece of 1x4 to fit lengthwise inside the duct. I offset the board to allow the inlet hole and outlet to be offset, top and bottom. I then installed two wooden baffles to block off the duct part way and cut holes in the vertical divider to allow air to zig zag its' way from top to bottom. I cut the holes for both pipes and secured collars to them. The upper hole accepts the vent cap from outside that I positioned just above the concrete wall of the basement and passes through the wood framed/stucco wall. The lower hole is connected to the stove using a flexible piece of 3 inch metal ducting formed into a "s" shape. I blocked off each end of the duct with pieces of wood, and sealed the corners. Painted the whole thing with barbecue paint, and installed it onto the wall panelling wth screws. When the stove is operating, the duct acts as a plenum chamber, and the warm air from the stove pre-heats the air as it moves toward the floor. The metal duct also acts as an extra heat shield behind the stove pipe, giving more peace of mind for us. The installation looks nice, and beats a length of "dryer" pipe hanging down the wall. I am experimenting with "thermal mass using the concrete blocks, and still have not decided if they are effective.

 

[oconnor]

"If a house does not have the EPA suggested air exchange ratio........an outdoor air supply is not the answer! It actuality leads to fewer air exchanges per day....and results in higher indoor air pollution levels! Combined with a small amount of wood smoke spillage that even an expert user experiences from loading, etc., it makes OAS’s look even worse.
Frank can you point us to some research that backs up your opinion? "

I don't believe the government has funded research into outside air feeds, and I can't imagine any private entity would sponsor such inquiry.

But that, as I'm sure you know, is not dispositive.

Your stove is not an air exchanger. If you have air exchange issues, then you should get an air exchanger - a wood stove would not serve the function in late April.

Here's a quote from the link you provided: "ASHRAE also notes that "dwellings with tight enclosures may require supplemental ventilation supply for fuel-burning appliances, including fireplaces and mechanically exhausted appliances."

Whoops. Looks like you supplied a cite that tells us to add an OAK if we have a tight house.

Thanks for the corroboration.

While your government may not have done any research, the Gov't of Canada has. I am sure as well that some Scandanavian Gov'ts have as well. Canada initially put OAK into the code as mandatory, then took it out. I don't see OAK as a holy grail, but as a tool - some enclosures MAY require extra ventilation. As for air use of EPA stoves, the only numbers I have ever seen was 10-25 cfm.

The biggest improvement I can see for an OAK is in a basement install, where the OAK can help isolate the stove from the effects of being installed below the negative pressure plane of the house, and by improving draft, also decrease the chance of the flue reversing flow.

That said, I can't find any fault with the logic that John Gulland presents at www.woodheat.org against OAK installs. While he mentions a risk of flow reversal caused by wind effect (I haven't seen any reports, but there are lots of things I haven't seen), I think his biggest issue was that they were made mandatory to improve indoor air quality, and they didn't do that to a statisically releveant level when the research was done. That doesn't mean that they aren't a great thing in some cases, just that they shouldn't be forced on everybody.

 

[NHenergy]

With everything mentioned I may have solved some of my problems. My stove may actually be to big for my home. A fresh air kit just might do the trick.

wow, a stove that's too big?! That's a RARE problem in my region!