Outside air drops and vents: legal and design questions

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jimmyb

New Member
Jul 7, 2021
6
westchester NY
Hello, I'm looking for some advice on the forum or for a referral to a qualified consultant for design help.

We live in Westchester County, NY in a 1926, 1400 sqft 2-story house with a 550 sqft daylight basement. I'm framing the basement and it'll be finished space. We're installing a GreenMountain 40 in the basement. It will use the existing center chimney that we had lined with new double wall pipe. - the run is about 35' to the roof.

Since we're going to insulate the basement with closed cell spray foam from the basement floor up into the sill plate, it will be a pretty tight space. And as I understand it the International Residential Code (IRC) does not allow the outside air duct to terminate higher than the appliance, so we won't be feeding this stove with directly connected exterior makeup air, so I guess we will crack a basement window if required.

That said, it is unknown if the heat in the basement will not find it's way upstairs. So while I'm framing the basement I'm looking at installing cold air drops on either end of the basement to bring cold air down from the first floor - assuming that this will help to force heated air to the 1st floor via the basement stairwell.

Two questions:
1) Is there anything in the IRC that supports the construction of cold air drops? I will need to send that our village building department.
2) Are there calculations that can be used to roughly size the openings on the first floor so we get this right the first time?
3) I've heard about some people running the drops down to within 18" of the basement floor and others run it only down 18" from the basement joists. Which one is right?

THANKS!
 

begreen

Mooderator
Staff member
Nov 18, 2005
94,547
South Puget Sound, WA
If this is a daylight basement, would it be possible to run an outside air pipe along the baseboard and out the ground-level wall?

Has draft been tested at the flue thimble with an incense stick or cigarette on a cool night?

You might also consider an HRV that has controls that allow one to set it to positively pressurize the room.
 

jimmyb

New Member
Jul 7, 2021
6
westchester NY
If this is a daylight basement, would it be possible to run an outside air pipe along the baseboard and out the ground-level wall?

Has draft been tested at the flue thimble with an incense stick or cigarette on a cool night?

You might also consider an HRV that has controls that allow one to set it to positively pressurize the room.
thx, bgreen. unfortunately we don’t have a walkout basement, it’s just that we have windows at grade level that provide light and air.

we haven’t tested the draft but we can do when the stove is installed.

yes, will look at the HRVs that are tuneable.

thanks for your ideas.