Thoughts on Outside Air Kits

[WKB]

Hey everyone,

Wondering how many of you have outside air kits installed with their pellet stoves. I originally installed this with our old pellet stove, thinking that outside air would increase the overall efficiency of the system, since heated air would not be used for combustion and exhausted. However, I've also learned that the warmer air of the house, when it's used for combustion, keeps your firebox hotter. And, there seems to be the continued possibility of introducing excessive humidity into your system when using outside air.

Any thoughts?
Thanks!

 

[imacman]

This has been discussed MANY times....do a search on OAK.

IMO, there is NO downside to an OAK on a pellet stove. Cold air also has more oxygen and should result in a hotter burn.

 

[Seasoned Oak]

This has been discussed MANY times....do a search on OAK.

IMO, there is NO downside to an OAK on a pellet stove. Cold air also has more oxygen and should result in a hotter burn.

Really? Iv read that cold water holds more oxygen ,but im not aware that cold air does, ill have to look that up.

 

[Seasoned Oak]

This has been discussed MANY times....do a search on OAK.

IMO, there is NO downside to an OAK on a pellet stove. Cold air also has more oxygen and should result in a hotter burn.

The air at the top of Mt everest is VERY cold yet hold very little oxygen. From what iv read ,a difference of a few dozen degrees wont make any difference in the amount of oxygen. ID go with the oak.

 

[fossil]

Density of air is inversely proportional to temperature. The lower the temperature, the heavier a given volume of air. A liter of cold air contains more of everything in the air (including oxygen) than does a liter of warmer air.

 

[Seasoned Oak]

Density of air is inversely proportional to temperature. The lower the temperature, the heavier a given volume of air. A liter of cold air contains more of everything in the air (including oxygen) than does a liter of warmer air.

Enough to change the performance of a pellet stove?

 

[fossil]

The elevation thing is a whole different phenomenon, having to do with atmospheric pressure. Air density decreases with elevation. But your pellet stove probably isn't going to climb Mt Everest.

 

[fossil]

Enough to change the performance of a pellet stove?

Probably not so's you could measure it. I'm just tossing out snippets of the laws that define the behavior of gases.

PV = nRT

 

[jtakeman]

I've also learned that the warmer air of the house, when it's used for combustion, keeps your firebox hotter.

I haven't seen any posted data. Can you share where you found this?

 

[SmokeyTheBear]

Get yourself three good textbooks one on thermodynamics, one on metallurgy, and the third on chemistry.

Then one can decide for themselves what to do.

 

[fossil]

Plus one on Gas Dynamics and one on Atmospheric Science and one on Mountaineering and one on Scuba Diving.

 

[stoveguy2esw]

he biggest benefit i see is that when you use "house air" you are drawing air you have already "paid to heat" through the stove and dumping it outside, now , this air has to be replaced from somewhere, so it leaches back in from outside through leaks in the structure. so you are "burning" warmed air, and replacing it with cold air.

burning with an OAK you are drawing combustion air from outside, using it and dumping it back outside. this results in less air infiltration due to negative pressure

either way you have to understand pulling house air removes heated air from a structure creating a vacuum of lower pressure which has to be relieved from leaks. pulling through an OAK does not

 

[SmokeyTheBear]

Or see if you can find the results of the pellet stove combustion experiments conducted by the Brookhaven National Labs.

 

[Seasoned Oak]

One thing is for sure ,without an OAK you will pull cold air into the living space probably where its not welcome. Unless you have air infiltration near your stove an OAK will keep the stove form creating cold drafts elsewhere in the house.

 

[Jon_M]

One thing is for sure ,without an OAK you will pull cold air into the living space probably where its not welcome. Unless you have air infiltration near your stove an OAK will keep the stove form creating cold drafts elsewhere in the house.

Like the one that comes in through the big bay window in my living room right over my shoulder when i sit in my favorite spot on the couch

 

[fossil]

Fix the leak or move the couch.

 

[SmokeyTheBear]

Air infiltration, normally the largest contributor to your home's heat loss.

Negative pressure in the stove room, the largest contributor to improper combustion and frequently the cause for smoke exiting the pellet stove at shutdown.

 

[Jon_M]

Fix the leak or move the couch.

On the "LIST"

 

[WKB]

I haven't seen any posted data. Can you share where you found this?

That's a very good point and thanks for asking. I only presume it makes the firebox hotter. Air intake manifolds on automobile engines and condensing boilers are surrounded by the warmth of exhaust gases, so I was extrapolating this to pellet stoves.

 

[WKB]

Plus one on Gas Dynamics and one on Atmospheric Science and one on Mountaineering and one on Scuba Diving.

Right! I have a degree in chemistry and some graduate work in P-Chem with specialization in atmospheric chemistry. Why does this then sound so complicated? Oy vey.

I was thinking about possibly taking air from the basement, since that space is probably a little leakier than the rest of the home. But I'm not quite sure that will pass the mustard in terms of town inspection. The manual "requires" OAK with a direct vent without vertical rise (my situation). But I do have a battery backup, which will apparently disallow a negative pressure.

 

[fossil]

...Why does this then sound so complicated?...

I have 3 degrees in Mechanical Engineering, and I'm convinced that sometimes things seem complicated simply because I make them complicated in my own mind. Outside air kit, or no outside air kit...just not that big a deal. If it's easy to install and you like the idea, put it in. If it's inconvenient to install or you're not a fan of the idea, skip it. Everything will be fine. Rick

 

[daffonce]

I did a quick energy balance assuming 10f outside air and 100cfm combustion blower 70f inside air and 55000 btu max output if I use outside air I can get 10% more heat out of the stove by not pulling heated air into the stove for combustion. This is because the 70f air going into the stove is replaced by 10f outside air through leaks. When it is 10f out my stove has a hard time keeping up with heating my 2400 sq ft house. So I installed the oak hoping that the extra 10% heat will allow stove to more easily heat the house. We will see this year.

 

[jtakeman]

I was thinking about possibly taking air from the basement, since that space is probably a little leakier than the rest of the home. But I'm not quite sure that will pass the mustard in terms of town inspection. The manual "requires" OAK with a direct vent without vertical rise (my situation). But I do have a battery backup, which will apparently disallow a negative pressure.

I have seen a few manuals where they have drawing basement air as an example.

 

[jtakeman]

I did a quick energy balance assuming 10f outside air and 100cfm combustion blower 70f inside air and 55000 btu max output if I use outside air I can get 10% more heat out of the stove by not pulling heated air into the stove for combustion. This is because the 70f air going into the stove is replaced by 10f outside air through leaks. When it is 10f out my stove has a hard time keeping up with heating my 2400 sq ft house. So I installed the oak hoping that the extra 10% heat will allow stove to more easily heat the house. We will see this year.

Keep us posted.

 

[WKB]

Anyone know why exhaust clearances to windows and doors is lessened with installation of an outside air kit?