Vent Question

Gas furnice in upstairs encolsed area-fresh air vents go from enclosed area into attic area. Is this OK or should it vent to outside?
Thanks, I need this info ASAP

Yes thats ok.

It’s OK as long as the attic has proper ventilation. It would have to be changed if the attic were insulated and the vents sealed as they are starting to do in some homes now.

Combustion air…?

What kind/size of enclosed area and how many floors between it and the attic?

This all depends on the size of installed unit, vent sizing, their location should be 2 hi/lo, what other gas appliances are in the proximety…there are supposed to be a manual/instructions present for all gas fired appliances…if they aren’t onsite I note as a deficiency and take down as much info (model/serial) about the unit and check it out back at the office…before sending report to client

probably not ASAP as you wanted but more info will be required before answered without this and photos

The furnace we recently installed in my house enclosed area needed 1 sq. inch of combustion air (split high and low) per 4000 btu input of all gas appliances in that enclosed area if run in vertically. And double that if run in horizontally. We came direct from outside.


I checked for my Rheem and the exact wording is:

“Each opening shall communicate directly, or by ducts, to the outdoors or spaces (crawl or attic) that communicate with the outdoors.”

As stated already, the attic is fine for combustion air as long as it’s vented properly. Gable end vents are not considered adequate with todays tighter homes.

A properly vented attic is basically…outside.

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