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Small Cabin Forum / Off-Grid Living / Wood Stove Cold Air Intake
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DaveBell
Moderator
# Posted: 16 Dec 2022 04:32
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I have seen cold air intake directly attached to the firebox. Either the manufacturer provides a knock out to attach or instructions that include using a 4" hole saw and attaching a duct adapter. If you think about the exhaust pipe size, probably don't want to go smaller than 4" on the intake. I would definitely want a valve on the intake to shut it off when not in use.

What I am curious about is having a cold air intake that is not attached to the firebox. Say plumbed under the bottom and to the front just to have it near the front intake vents. That would make installation of the stove easier, moving the stove afterwards easier, replacing the stove easier, etc.

I just don't know if there would be any major disadvantages. It would have bug/rodent screens outside and inside. I don't think there would be a pressure issue, connected or not, if the stove wants more air and the intake is not enough, it will get it from leaks in the structure.

Brettny
Member
# Posted: 16 Dec 2022 07:45
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Unless your stove cant get a draft going and keep it you alreaty have a fresh air intake like you say. Its every crack and air leak. You need to connect the outside to the stove intake to see the benefits. Why cant you connect a duct to the air intake?

I built mine my self. My stove had a rectangle intake with two bolts and built an adapter to change it to 4in dryer vent.

toyota_mdt_tech
Member
# Posted: 17 Dec 2022 21:12
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My woodstove at home was professionally installed and has a hole in the floor, air comes in from the pedestal. There is a screen in the way to protect from varmints.

Its a Quadrafire 3100 Millennium flat top.

Ontario lakeside
Member
# Posted: 19 Dec 2022 09:36
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I added a cold air intake to our stove. The stove did not have a pre cut hole so I cut one into the ash drawer. This allows air up into the firebox. It worked very well. I made a video of what I did if you want to see.
https://youtu.be/aAwKBIx2YzQ

KelVarnsen
Member
# Posted: 20 Dec 2022 08:33
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Quoting: Ontario lakeside
I made a video of what I did if you want to see.


Thanks for sharing. This has been on my To Do List for a couple of years. I really should get to it.

DaveBell
Moderator
# Posted: 20 Dec 2022 09:17
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Quoting: DaveBell
What I am curious about is having a cold air intake that is not attached to the firebox.


travellerw
Member
# Posted: 20 Dec 2022 11:55
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Quoting: DaveBell
What I am curious about is having a cold air intake that is not attached to the firebox.


Ahhh.. I have that. I just crack a window about 2ft from the fireplace (we really do this)

Seriously though. You absolutely can have a cold air intake that is not attached, however it will leak a fair amount of cold that is not used by the stove (especially along the floor). You could put a damper on it and figure out where it supplies enough just enough air though. I would make sure it is close to the fireplace though as the cold incoming air rushing towards the fireplace is darn cold. Its best to not have any furniture between the fireplace and that vent. We had to move a chair because of that.

Nate R
Member
# Posted: 20 Dec 2022 12:47
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I've been thinking about doing a disconnected air intake that's heated, using one of these PTC fan heaters: https://dbkusa.com/collections/cirrus-series-ptc-fan-heaters

gcrank1
Member
# Posted: 20 Dec 2022 14:07
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Decades ago, with our 1st cabin 12x24 cw 12x12 loft, all we had was an antique, cheap in its day, cylindrical upright woodstove while a 6" pipe. I thought about cutting an intake hole in the floor pretty much under the air intake lower door, a straight shot up as the stove was breathing. Easy to cap off, use a regular stovepipe draft flap and at least hardware 'cloth' screening at the bottom. Conceptually it should work fine for cold-air intake but it would mess up the fire protection pad....and I couldnt bring myself to cut a hole in my floor. My thought always came back to,"what if I move things around in here?".
Then I considered a hole in the wall behind and running a 4" pipe to the same spot. Never did it but it should work, no messing up the floor, and if it was a fail the wall hole wouldnt be bad to fix.

Brettny
Member
# Posted: 21 Dec 2022 08:49
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Quoting: travellerw
ave a cold air intake that is not attached, however it will leak a fair amount of cold that is not used by the stove (especially along the floor). You could put a damper on it and figure out where it supplies enough just enough air though. I would make sure it is close to the fireplace though as the cold incoming air rushing towards the fireplace is darn cold. Its best to not have any furniture between the fireplace and that vent. We had to move a chair because of that

By opening a window your not getting any benefits of having a outside air intake of the stove. Your just letting fresh air/cold air into the building.

travellerw
Member
# Posted: 21 Dec 2022 15:31 - Edited by: travellerw
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Quoting: Brettny
By opening a window your not getting any benefits of having a outside air intake of the stove. Your just letting fresh air/cold air into the building.


The window is 2ft and right above the stove. You can actually feel the cold air flowing towards the stove. On really cold nights you can even see it (fog). It makes a huge difference in the temps of the outer room as the stove no longer pulls air from leaks in those rooms.

All stoves are a little different, but you should be able to find where the stove is pulling air in. On ours its on the bottom and when the damper is fully open you can easily feel it pulling in air. Opening the window next to the stove has the cold air fall down to the floor and be pulled towards the stove. Essentially feeding it outside air. Very little of the cold air seems to remain in the room as the temp in that room doesn't change. However, we do just "crack" the window open. Maybe an inch.

travellerw
Member
# Posted: 21 Dec 2022 15:36
Reply 


Another quick note.. Opening that window and then preheating the chimney (used to use newspaper, now I use a propane weed burner) is essential for a smoke free experience. When I do things right, absolutely no smoke leaves the stove. There is zero smoke smell in the building.

gcrank1
Member
# Posted: 21 Dec 2022 19:14
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I do like the smell of woodsmoke.....
How about making a simple 'panel' to sit at that window gap with a snorkel down to the floor or stove?

travellerw
Member
# Posted: 21 Dec 2022 22:19
Reply 


Quoting: gcrank1
How about making a simple 'panel' to sit at that window gap with a snorkel down to the floor or stove?


I did actually think of something kinda like that.. but it seemed like a lot of work for no real gain.

If I was going to invest some time and energy, I think I would just do a proper cold air intake. There are just so many other jobs and the cracked window just works.

Energico
Member
# Posted: 26 Dec 2022 13:07
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I've been contemplating this, too. My closest window is the only double pane in the house, so it doesn't make sense to crack that open.

gcrank1
Member
# Posted: 26 Dec 2022 14:25
Reply 


Just read on another site where they used a 4" dryer vent pipe low in the wall and feed it right under the stove; used a flap shut-off. Said it worked great.
My impression was the stove stack was 6".

BRADISH
Member
# Posted: 4 Jan 2023 17:01
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I did this for my wood stove. A 4" dryer vent directly under the woodstove, it comes up through the pedestal. It stays open 24/7 and haven't found it to allow any drafts in (I figured any incoming air would be warmed by the stove's warmth). It draws from below the cabin, although the foundation is skirted so it keeps direct wind from coming in. It is screened for rodents/bugs as well - although I'm not too concerned with rodents as it is still 5' off the ground.

I never ran the woodstove without the fresh air intake, as I put it in prior to stove installation - however I have no regrets - i'd do it all the same again.

Brettny
Member
# Posted: 4 Jan 2023 20:38
Reply 


Quoting: BRADISH
It stays open 24/7 and haven't found it to allow any drafts in

That's the thing about a properly sealed wood stove. Its sealed up to the interior except for the air intake. If you move that into to the exterior the only other opening in the stove is the chimney. Thus it wont make any drafts.

BRADISH
Member
# Posted: 5 Jan 2023 11:09 - Edited by: BRADISH
Reply 


Quoting: Brettny
That's the thing about a properly sealed wood stove. Its sealed up to the interior except for the air intake. If you move that into to the exterior the only other opening in the stove is the chimney. Thus it wont make any drafts.

I guess I should have been more clear in my description - my setup is nearly identical to what DaveBell is describing here:
Quoting: DaveBell
What I am curious about is having a cold air intake that is not attached to the firebox. Say plumbed under the bottom and to the front just to have it near the front intake vents. That would make installation of the stove easier, moving the stove afterwards easier, replacing the stove easier, etc.


My air intake comes in under the pedestal, which is open in the back, and stands about 3-4 inches into the pedestal 'void' stopping well short of the stove's actual air intake. So definitely nothing sealed about this system.

I did this so it could also act as an air relief for my range hood fan, and shower fan. My building is quite tight.

But still not experiencing any drafts, even with 35mph winds we had in a recent storm over NYE.

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