wood stove, fresh air intake size?

[Groo]

I know fesh air intakes are a bit contriversal, but I can't run my wood stove safely now as is and have plans to mitigate the potential downsides of a fresh air intake.

my question are:

What size should a fresh air intake be?

Is it worth sticking a fan on a fresh air intake?

 

[RNeumann]

No to the fan and typically it’s the same size as dryer duct- 4”. Just make sure to take the flapper out of the dryer vent termination.

 

[Beltzington]

I know fesh air intakes are a bit contriversal, but I can't run my wood stove safely now as is and have plans to mitigate the potential downsides of a fresh air intake.

my question are:

What size should a fresh air intake be?

Is it worth sticking a fan on a fresh air intake?

When we lived in Nebraska, I had a modern (catalytic chamber) wood stove located in the basement with a fresh air inlet. I used 4" rigid galvanized vent pipe for the outside air, total length was about 14' (4' horizontal and 10' vertical.) We used the stove a lot and never had any issues with air draw. You will need to leave the door open just long enough for the wood to catch and then you can close the door and regulate with the stove damper. Once the wood was burning well I almost had to close the damper to keep the exhaust temps within the safe zone so I cannot imagine you ever needing a fan on the intake.

 

[Raspy]

I ran a 5" combustion air duct to the rear of my woodstove. It has (2) 90s and about 30' of straight pipe. Outside it has a screen to keep bugs out. I connected it directly to the stove so all the air had to come through the duct. Then later, I replaced the stove with a different model and left the air duct disconnected and terminating at the wall behind the stove. It just terminates near the rear of the stove and I can feel cool air coming in when it's burning. The new stove has an 8" exhaust vent and the original one was 6"

Both setups worked fine, but I suspect the first one worked well partly because I have about 15" of vertical exhaust for a strong draft. Not sure on how much affect that had.

My air supply pipe terminates on the side of the house and it seems possible that wind coming from the other side of the house could cause negative pressure on that pipe and make the stovepipe draft less affective.

In theory, you won't get the same drying affect as you would pulling room air, but the fire will run more dependably, there won't be any drafts and there will be no need to crack a window.

There is no need for a draft fan as it will never match the varying needs of the woodstove and all that we really want to do is not have negative pressrue in the house. So an open pipe works fine.

 

[teg]

Interested in what people say... I figure my Dryer vent and bathroom fans were our "fresh air" intake vents!!!!

 

[Raspy]

Interested in what people say... I figure my Dryer vent and bathroom fans were our "fresh air" intake vents!!!!

Not if they have flap shutters on them and not if they terminate behind a closed door.

 

[RalphVa]

Interested in what people say... I figure my Dryer vent and bathroom fans were our "fresh air" intake vents!!!!

They usually have flappers on them to discourage air from coming in. Plus, a dedicated fresh air inlet will tend to keep the stove from sucking COLD fresh air into your house.

Ralph

 

[Ford850]

I have a 3" PVC pipe in the basement ceiling, poked out above the sill plate. It dumps into my furnace/water heater room which is within 10' of my woodstove. There's a 1 1/2" gap along the bottom of that furnace room door, so air can flow out to offset the stove's draw. It also helps feed air to the propane furnace and power vent water heater. Those two used to create negative pressure occasionally making it difficult to keep a good draft in the stove flue.
If you add a fresh air intake, be sure to keep it fully insulated. It will frost and drip otherwise.

 

[Groo]

I was thinking the fan might get the secondary burn going better, and it could be turned off and on as needed.
I was also thinking smaller than 4". Stoves don't use much air. Is 4" used because it is cheap and availiable or is that much area really needed? The smaller the hole I drill through my foundation wall, the happier I'll be.

 

[Egon]

In some areas fresh makeup air to the interior of the house is mandatory.