Gas Furnace ventilation Question

OK so I did a pre drywall inspection today, and the building super was there. The Gas furnace is installed in a closet in the garage which has basically no air ventilation nor louvers on any wall or doors. He told me that is is now ok to be like this because it vents to the outside ?
Anyone can verify or dispute?

I would say he is correct. See intake air for combustion here

Yes, check out the link from Robert to brush up…exhaust and intake piped to the exterior.



This is what I see in the north part of the country, And the freash air and the exhaust does exit to the exterior normally though the rim joist, However I need to pay atttention to to the distance above GRADE the code says 12 inches above grade. I like to see it above this distance just for safety reasons.

Thanks guys and especiaally Robert, good reading for sure.


Had one yesterday the furnace was a 90% with combustion air from the exterior located in a interior hall closet with a gas fired water heater sitting in the same closet that changes the rules;-):wink:

Many of these new units do directly vent to the outside, tough to tell from the pic where it goes, but he’s likely correct on this one.

I would change that to " these new units can directly vent to the outside", I find it difficult to find anyone to waste 20 bucks on another length of pipe to hook it up.

If this pipe is not hooked up, the 90% capacity of the furnace become significantly less.

Looks like you were doing a foreclosure inspection James as the gas valve is in the off position.

Yep, it means the closet needs to be vented.

Bob actually this is a Pre Drywall inspection on a new Townhouse.:roll:


Will that enclosure maintain the fire barrier between the garage and the house? Will it be clad in sheetrock with a fire rated door? If not, then when the fire reaches that room, it spreads via the flex ducts to the rest of the house. Something to think about.