Thoughts on Outside Air Kits

WKB said:

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

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Because the stove isn't sucking cold air into the house by the means of the leaky windows near the stove which could let in exhaust gases. Its using the OAK to draw in the air. Less chance of gasses entering the home

WKB said:

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

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maybe because the stove wont be sucking air in around the window using oak instead of house air

WKB said:

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

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Because the exhaust gases are not being sucked into the house like they are without that OAK, think for a minute about what it means to pull your combustion air through cracks in the houses exterior, which it just so happens are usually round doors and windows.

The exhaust clearance is to keep the exhaust gases from being sucked into the living space.

people sometimes forget to completely close windows. windows aren't new forever.
and if for no other reason, (and avoiding CO poisoning is definitely a good "other" reason) a proper installation according to manufacturers specifications satisfies insurance requirements.

stoveguy2esw said:

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

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X2

WKB said:

Right. But I wonder what the real probability of this is with new, vinyl replacement windows. Closed, of course!

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Trusting a builder/re-modeler to make a window gas tight is not something I'd do and then consider how is it possible for a gas tight window to operate when you have to open it. In other words they ain't as tight as you might think even when installed properly..

true, and think about the framing around it, if its not totally sealed as well the leak could get in around the frame even if the window is airtight

fossil said:

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

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And please do not forget the book (or books) on physics! Gads...

And be sure to watch several episodes of the TV show, "The Big Bang Theory" to get into the mood of this debate.

In Sheldon Cooper terms: I say that burning w/o an OAK causes the stove to draw in air which is pre-heated by the stove. The pre-heated air has a reduced amount of energy depending on the thermal efficiency of the stove (compared to the energy inside firebox). Thus the stove cannot possibly heat the 'pre-heated house air as efficiently as it can heat cold air coming in from a OAK. Also if you have a small house (say, less than 1600 sq. ft.), a non-OAK stove can easily double the amount of draft and therefore greatly reduce the heating effect of a stove and create drafty cold spots in the smaller house. In a tight house, a no OAK stove can lead to reverse venting and negative pressurizing causing several types of problems. Also in my case, OAKs are required by law in HUD houses in the US, as well as new construction and with all stoves and fireplaces being installed in WA state, so it is a moot point for many of us.

WKB said:

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.

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Your stove is not manditory

Very simple for me. When I first put in my stove it ran ok but not great with no OAK. After I installed the OAK, I had a white hot inferno of death keeping the majority of home 73 degrees from from the basement. So I would say the OAK made a big difference.