View Full Version : New furnace needs more air - pull from outside or inside?
05-12-2009, 11:00 AM
Code changes require that my new gas furnace (backup for a new heat pump) requires more air than it currently can get in its closed, small interior room.
I can either have the installers:
1. cut 2 fairly large holes (14"x10") in the sheetrock of a large, finished basement room and pull conditioned air from there (one would be right next to the return for the basement), or
2. go through the outside wall and pull unconditioned air.
For aesthetic reasons I'd prefer to pull combustion air from the outside, but appreciate any feedback.
05-12-2009, 11:30 AM
Code around here requires you to pull combustion air from the outside. Usually done with a barometric damper tied into the return air, however a trapped flex duct into the furnace room is acceptable too. Common sense says to pull the air from outside because using indoor air will deplete the structure of oxygen leading to many problems. Make sure the combustion air is sized properly. It must be able to handle all exhaust sources as well as combustion equipment.
05-12-2009, 01:42 PM
The installations intructions for your furnace should also give you some insight here, in terms of how to source combustion air - may depend on the manufacturer, type of venting, efficiency of the furnace, etc, etc. In general, outdoor air is preferred as pulling indoor air is totally dependent on infiltration to replace it.
05-12-2009, 10:19 PM
I had to do that with my house because of a relocated gas water heater. The 2 holes are covered with a grille and doesn't look too bad
05-13-2009, 07:23 PM
The room that it is in...does it have a door to it? If so could you install a louvered door? Might be a quick solution. But I agree that the best bet would be to pull in outside air....
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