outside air kit. Worth it?
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johnnywarm said:
Unfortunately I'm not talking about having any of the doors or windows open, I mean my house is well-ventilated with everything shut. I'm talking about all the cracks and seams and leaks in this old house - the outside air kit was pretty much built in 300 years ago!
thechimneysweep said:
Don't believe it. Something is always causing negative pressurization in most house. Yes, heated air expands, but it also rises as it becomes less dense. Stack effect states you will have lower air pressure at lower levels of the house, higher pressure at higher levels. Every house will be different depending on how well it is sealed at different levels.
An infrared photo (demonstrating heat loss from a house) has red spots around the doors and windows, but that is showing heat being radiated out, not air flow. Heat will radiate through a completely airtight window. Infrared radiation "flows" warm to cold, and does not need to have anything to do with air flow.
Put your hand at the bottom of an outside door while standing inside my house in the winter and you will get cold. Now go outside and try to warm your hand on the other side - ain't gonna happen. Hot air does not flow out the bottom of my doors.
The cold air is flowing in at the lower levels of the house, then warming and flowing out at the upper levels, especially up any unused/unsealed chimneys I have (they are all getting sealed or used this year!).
My house is leaky at the bottom and tight at the top. The neutral pressure plane is at a fairly low level of the house and I have great draft. And I'm gonna need it. The lucky thing is guys like me with old, leaky houses get a good natural draft.
Well put, Branchburner.
Also, as for the wam air in the house expanding, that only applies as the temperature of the air is rising. Reality is that the air temperature inside the house flucuates up and down as does the outside air temperature. The net result is no pressure change due to heating a house.
Also, as for the wam air in the house expanding, that only applies as the temperature of the air is rising. Reality is that the air temperature inside the house flucuates up and down as does the outside air temperature. The net result is no pressure change due to heating a house.
The start of wisdom is calling things by their right names - chinese proverb
Mr thechimneysweep
I don't believe it. I'm not saying that an OAK can't be useful, nor am I saying it isn't mandatory in Washington State. There are certainly valid technical reasons to install them.
What I'm saying is that what you are saying doesn't make sense to me.
I don't believe that a manometer is going to sense a pressure increase when I fire up a heat source in my house. Increasing bouyancy of air, and expansion of air due to heating does not equal a positive pressure situation, it equals stack effect. Stack effect means some air leaves, and some air enters. If the house was at a positive pressure, that is to say pressure above the ambient pressure outside the house envelope, air would not be entering, only leaving.
I don't believe your analysis of IR imagery of houses. IR doesn't detect air currents, only radiant temperature differences. The high heat spots around my windows are where poor insulation techniques are allowing heat to escape.
For those looking into an outside air kit, I would recommend they look at all the sources of possible combustion spillage/poor draft, and weigh your options. If local code/bylaws say you must have one, then I guess they know best.
Lets see if Washington state changes it's mind on this issue just like to Governement of Canada did in 1995, and takes OAK requirements out of its code.
Mr thechimneysweep
I don't believe it. I'm not saying that an OAK can't be useful, nor am I saying it isn't mandatory in Washington State. There are certainly valid technical reasons to install them.
What I'm saying is that what you are saying doesn't make sense to me.
I don't believe that a manometer is going to sense a pressure increase when I fire up a heat source in my house. Increasing bouyancy of air, and expansion of air due to heating does not equal a positive pressure situation, it equals stack effect. Stack effect means some air leaves, and some air enters. If the house was at a positive pressure, that is to say pressure above the ambient pressure outside the house envelope, air would not be entering, only leaving.
I don't believe your analysis of IR imagery of houses. IR doesn't detect air currents, only radiant temperature differences. The high heat spots around my windows are where poor insulation techniques are allowing heat to escape.
For those looking into an outside air kit, I would recommend they look at all the sources of possible combustion spillage/poor draft, and weigh your options. If local code/bylaws say you must have one, then I guess they know best.
Lets see if Washington state changes it's mind on this issue just like to Governement of Canada did in 1995, and takes OAK requirements out of its code.
It's not just the state of WA. All mobile homes must have outside air ducted in and I believe many states have the same requirement. Even if it isn't required, it is still a good idea just to keep the humidity in the home and to keep heated air in the home.
all I can say is I see no harm in having an OAK. if I were to do a New install in a new house I would have one just because I can see no harm in it.
Can you run an OAK up and out the roof kinda like a chimney or i guess more like a drain vent?
Can you run an OAK up and out the roof kinda like a chimney or i guess more like a drain vent?
Claiming outside air decreases depressurization, which sounds good, works if it is installed on the WINDWARD SIDE OF THE HOUSE. Since the wind does not blow from the same direction all the time, this can lead to it being on the LEEWARD SIDE OF THE HOUSE which will have a negative effect and INCREASE depressurization. You don't want to do this.
Read www.woodheat.org about outside air. It is antiquated concept from back when heaters were installed in small trailers years ago. It is usually not necessary UNLESS YOUR LOCAL BUILDING CODE REQUIRES IT.
Putting extra holes in one's home is usually not a good idea anyway. Same goes for boats.
Aye,
Marty
Read www.woodheat.org about outside air. It is antiquated concept from back when heaters were installed in small trailers years ago. It is usually not necessary UNLESS YOUR LOCAL BUILDING CODE REQUIRES IT.
Putting extra holes in one's home is usually not a good idea anyway. Same goes for boats.
Aye,
Marty
Which is why in my experience the OAK intake should actually be on two sides of the house to prevent this if possible.
I think many people on both sides of this debate forget that with a little good design practices, potential problems with OAK systems can be eliminated and only the benefits remain.
I would say no-go on the garage air source, reason being that the stove could intake fuel fumes. The same reason that the garage is usually off-limits for the installation of a wood stove.
crazy_dan said:
Uh, I don't think that sounds like a good plan.
The OAK would then seem to have the potential to cause serious harm, as it could become the chimney.
When an OAK is installed, I think it is to be installed to draw air from a level below the stove (I recall reading that it must draw from a location outside that is 4 inches below the stove, but not having one, I haven't looked at it since)
Let a good, well trained installer tell you how to hook it up, or better yet, have them do it for you.
Any body else got an opinion on an OAK running up thru the roof like a chimney??
Marty
Does yours run up thru your roof like a chimney?
As I said, I am not about to quote code here, but running a direct connect OAK up thru the roof just doesn't seem right.
Does yours run up thru your roof like a chimney?
As I said, I am not about to quote code here, but running a direct connect OAK up thru the roof just doesn't seem right.
outside air kit ? YES YES YES! pellet stoves are more efficient with em , bringing some fresh air to assist is always a good idea!
I wish CT gave a tax credit
LOL
I wish CT gave a tax credit
LOL
My stove is in the basement below grade. I also have a heat trap before my direct connect to the stove. The outdoor air supply is located 2ft above ground above the snow line way above my stove.
oconnor said:
Agreed - a roof-OAK not only doesn't seem right, seems crazy (but then, I'm mildly insane myself).
If the OAK is sized/positioned correctly, unobstucted, and at or below stove level I can't see any reason not to use one. If my house was sealed up tight I would do it. As leaky as it is, I thought it might reduce draftiness, but with an antique center chimney it didn't seem like a simple thing to do. That kind of sums up my two either/or requirements for doing stuff in general (not always in the order listed), neither of which was fulfilled regarding outside air:
1) It's needed
2) It's easy
I was thinking out loud for the folks with a stone or brick hearth that it would be a PITA to plumb one the normal way.
Just kinda thinking out loud. Going that route would require the use pellet stove chimney. just to clarify once again Purely hypothetical.
Just kinda thinking out loud. Going that route would require the use pellet stove chimney. just to clarify once again Purely hypothetical.
oconnor said:
No. It runs to the "windward side" )side prevailing winds come from) of the house.
Aye,
Marty
crazy_dan said:
I think I read for pellet stoves that outside air needs to originate a few inches below exhaust level, not appliance level, so I think in theory you can draw your air down from above. But that may be for pellet stoves that use a fan to force the exhaust out the vent. Stoves with a natural draft would be different I imagine. I know nothing about pellet stoves but the case for outside air in that application may be very different than for woodstoves.
It seems to me that as my flue size has decreased from 144 sq inches to 28 sq inches and my combustion efficiency increased greatly with an EPA stove, my need for a dedicated air source is much less than it used to be. When I really needed it was when it was impossible to get: with a big open fireplace! You could feel the cold front moving right in with that thing gobbling up the splits. I don't know how our founding fathers had time to do anything besides cut wood.
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