Heat duct in garage - InspectionNews

Paul Kondzich · #1 (**permalink**) 09-24-2007, 09:22 AM

I am having a brain freeze here. What are some reasons why you would not want a heat duct from the furnace to exit into garage. It has no damper or grille, just a hole in the drywall, and a hole hacked i nto the metal duct. Thanks.

David Banks · #2 (**permalink**) 09-24-2007, 09:39 AM

R309.1.1 Duct penetration. Ducts in the garage and ducts penetrating the walls or ceilings separating the dwelling from the garage shall be constructed of a minimum No.26 gage sheet steel or other approved material and shall have no openings into the garage.

Potential for gas vapors/carbon monoxide to be sucked into house.
Break in firewall?

Jon Randolph · #3 (**permalink**) 09-24-2007, 10:21 AM

Don't forget about jeopardizing the fire wall by cutting through it.

Ross Neag · #4 (**permalink**) 10-16-2007, 10:35 PM

Am I missing the phrasing of this? R309.1.1 Duct penetration. Ducts in the garage and ducts penetrating the walls or ceilings separating the dwelling from the garage shall be constructed of a minimum No.26 gage sheet steel or other approved material and shall have no openings into the garage.

If it penetrates the space it must be no 26 or other approved metal. But it shouldn't penetrate the space.

IMO, I prefer either a sleeve unit or if you can swing it, a ceiling hung unit...unless infrared is available. Ah hell, I should just live in FL.

Jon Randolph · #5 (**permalink**) 10-17-2007, 04:53 AM

Ross,

I think that you are confusing penetrating and terminating.

Penetrating (ie. going through) is the solid duct going through the space, which is allowed.

Terminating, with an opening to the garage, could allow noxious fumes to enter the home and is not allowed.

Jerry Peck · #6 (**permalink**) 10-17-2007, 05:38 AM

Paul,

Quote:

Originally Posted by Paul Kondzich

What are some reasons why you would not want a heat duct from the furnace to exit into garage.

I believe this is confusing people, I know it is confusing me ...

Quote:

It has no damper or grille,

just a hole in the drywall,

and a hole hacked i nto the metal duct.

Let's see if I have this right:

No damper or grille ... but there is a hole in the duct supplying air to/taking air from the garage?

26 gage can be run through (a "through penetration" when talking about a 'fire rated wall assembly', but a garage/living space *IS NOT* a 'fire rated wall assembly', it is only a 'separation wall') the garage wall, however, no return air is allowed to be taken from the garage or supply air given to the garage 'from the living space system' (there could always be a 'separate system' for the garage which only serves the garage).

Another type of "penetration", but which does not apply here, is a "membrane penetration" (versus a "through penetration"). A "membrane penetration" is like an electrical box 'set into' the wall, it "penetrates" the membrane on one side of the wall, but it does not 'go through' the wall.