Outside air intake

[Baby Grand]

KennyD mentioned stack effect, which is the reason I'm adding an OAI duct for our basement stove. We have a 1950's one story ranch with a full basement. The stove operates well on cold, calm days once the burn gets going and I shut the damper down. The key to getting good heat out of the stove is maintaining a hot, even burn. Using the dryer, bathroom fans, our kitchen fan, and when the oil furnace kicks on causes the pressure inside the house to drop. This pressure drop reduces the chimney draft, changing the burn rate noticeably. Opening a window a little equalizes the house pressure, chimney draft and burn rate, but let's cold air into the house. Plus I always forget to close the window once the fan is turned off. The OAI should achieve the equalization without the chilling side effect and the inevitable discussion about "why I always leave windows open when it's freezing outside".

 

[arrow]

There are a myriad of answers to my original post. Some based on theory, others based on actual usage. All that is fine because everyone's situation is different. I have always discovered my personal answer somewhere between all the replies. Helps to coagulate the brain so to speak so thanks for your time.
It's a cheap enough tactic to at least attempt. I was also considering getting a powered register fan to draw more air out of the cellar but I need to do one thing at a time so as to relate any difference.

 

[arrow]

So I installed an outside air intake for $25. Drilled a 4" hole through the sill and attached all the hardware and tube directly to the specified port at the bottom of the wood stove. I rigged it so I could shut it down for comparisons. Ran like this for a week. Here is what I found for my particular set-up:
1.The oai did absolutely nothing for the temp of the house. Temps remained the same with it or without it.
2. With the oai running, wood was used up in half the time. What was previously an 8 hr load of wood became a 4 or 5 hr charge.
3. Here is the most important thing: although the temp in the house did not alter between the two methods, the house "felt" warmer without the oai being attached.

I believe the interior currents of the house allowed an air flow that was more sweeping toward and around the wood stove which carried more surrounding heat for the rest of the house as the stove was using interior air for combustion. I have no proof of this but it is what it felt like.

Convection currents were much quieter in activity with the oai and thus, so the heat movement. My stove is considered a "convection" type as opposed to a radiant type with most of the heat coming from the top off the stove.
I'm glad I tried it and it was worth the small investment to find out.
For my particular set-up, an oai was not conducive to a more comfortable house.
Also, I was not a fan of the reduced time of burn.

What was interesting is that the wood stove had a better draft when I left the 4" pipe adapter at the borttom of the stove. I guess this kinda acted as a "carburetor spacer" would to create better air flow into the stove. And yes, even this reduced burn time but not nearly so much as with a direct outside air flow coming into the stove.

 

[deezler]

^ Thanks for Sharing your experience!

I have one recent anecdote to share myself: After 4 winters of use, I decided it was time to replace the gasket on my woodstove door (Napoleon 1450). The door just didn't feel super tight when closed, but after a new gasket installed, is way tighter. My draft is now stronger and more consistent, and burn times are longer (if I damp the intake down all the way). So just a PSA that if your stove door is leaking at all, it could give you burning problems that can appear to be house/draft/intake air related. You ONLY want to let air in through the engineered locations on your stove.

 

[nyone]

Its really hard to measure the differance a Outside Air Kit makes in just a week. Change in firewood, outside temp or damper possition just to name afew can skew things. Bot to mention how well the house is sealed.

For my house a 1930 house that we rehabbed about 6 years ago an OAK made my house alot warmer, less drafty and i burned less wood. I built mine my self out of metal from my garage and a piece of aluminum dryer duct.

In theory these have to work. Your chimney constantly has air from your house going right up and out with out one. That air is alreaty heated and is now replaced with cold outside air. If your house is so tight you dont think your getting cold air in you would also not have smoke going out the chimney, it would leak out of every crack or seam in the stove.

 

[Egon]

So I installed an outside air intake for $25. Drilled a 4" hole through the sill and attached all the hardware and tube directly to the specified port at the bottom of the wood stove. I rigged it so I could shut it down for comparisons. Ran like this for a week. Here is what I found for my particular set-up:
1.The oai did absolutely nothing for the temp of the house. Temps remained the same with it or without it.
2. With the oai running, wood was used up in half the time. What was previously an 8 hr load of wood became a 4 or 5 hr charge.
3. Here is the most important thing: although the temp in the house did not alter between the two methods, the house "felt" warmer without the oai being attached.

I believe the interior currents of the house allowed an air flow that was more sweeping toward and around the wood stove which carried more surrounding heat for the rest of the house as the stove was using interior air for combustion. I have no proof of this but it is what it felt like.

Convection currents were much quieter in activity with the oai and thus, so the heat movement. My stove is considered a "convection" type as opposed to a radiant type with most of the heat coming from the top off the stove.
I'm glad I tried it and it was worth the small investment to find out.
For my particular set-up, an oai was not conducive to a more comfortable house.
Also, I was not a fan of the reduced time of burn.

What was interesting is that the wood stove had a better draft when I left the 4" pipe adapter at the borttom of the stove. I guess this kinda acted as a "carburetor spacer" would to create better air flow into the stove. And yes, even this reduced burn time but not nearly so much as with a direct outside air flow coming into the stove.

Do you have an airtight stove with draft control on the outside air??

 

[arrow]

Do you have an airtight stove with draft control on the outside air??

Yup. Deezler makes a good point about the door seal. I replaced mine about 3 years ago and door still seems tight to shut.
The point nyone makes is also valid about using it only for a week. The difference was so out-right, I didn't need further experimentation.
House was "less" comfortable. House being a log home is super drafty but the house currents were more "still" with the oai. Stove being in the cellar may have made the particular difference as opposed to being in a living space. The heat output was simply too "unidirectional" going straight up. It seemed to need the extra pull of yanking interior intake air and moving heat around better.

Whatever it was created a noticeable difference. Perhaps the largest detriment for me was the extra wood being used. The week I made the study had a couple nights in the mid teens. Both following mornings the main floor of the house was at 64* with and without the oai. Coals were considerable less after the 8 hr nighttime burn with the oai.

No matter what premises anyone makes on this forum, the one thing that remains constant is "the devil in the details". What works for one doesn't necessarily correlate for another. That is why I tried to include my situation with particular set-up.

 

[nyone]

I assume you dont keep it 64* most of the day? We like 69-73*, i didnt cut, split, stack and then drag the wood inside to be cold in my living room. Our stove is about 10ft from our couch. Any basement stove i have used always takes major time to get the heat into the living area. My father says it takes about 2 days for a major temp change, we have the same wood stove. A vermont castings defiant. I have gone 24hrs without loading this stove.

Arrow do you have vents cut in the floor/ceiling? I find moving the cold air to the stove really moves the hot air to the coler place yet dosnt cool the hot air.

 

[MossRoad]

^ Thanks for Sharing your experience!

I have one recent anecdote to share myself: After 4 winters of use, I decided it was time to replace the gasket on my woodstove door (Napoleon 1450). The door just didn't feel super tight when closed, but after a new gasket installed, is way tighter. My draft is now stronger and more consistent, and burn times are longer (if I damp the intake down all the way). So just a PSA that if your stove door is leaking at all, it could give you burning problems that can appear to be house/draft/intake air related. You ONLY want to let air in through the engineered locations on your stove.

I have the same stove and also replaced my door seal with a thicker one after the 2nd or 3rd year. It's been good for 7 now.

Also, if you don't know about it, there's a gasket that goes over that center metal piece with the holes in it at the top of the box. It's called the secondary air manifold. It runs from front to back. The two baffles rest on it. That gasket gets burnt out every 3-4 years for us. It's called the secondary air manifold gasket. Page 31 of the manual....

https://www.napoleonproducts.com/downloads/fireplaces/manuals/W415-1468.pdf

 

[ultrarunner]

Still getting acquainted with the set up at the new place... existing cat wood stove insert with blower and stainless pipe to daylight...

The stove puts out a tremendous amount of heat and burns the wood to white ash... the glass stays amazingly clean but this is the first experience with this type of stove dating to 1993 install.

The outside air damper works very well...

That said I am surprised at the slight lingering smoke smell in the living room when using it???

Door gasket nice and tight and the stainless looks great and I can inspect just about all of it...

Is it typical for there to always be at least a hint of lingering smoke odor when heating with wood?

Stove has not had much use as most of the "Cold" winter nights it is illegal to burn wood here SF Bay Area... but it did a nice job when the power was out 59 hours!