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  1. #1
    Join Date
    Apr 2008
    Location
    Winston-Salem, NC
    Posts
    15

    New furnace needs more air - pull from outside or inside?

    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.

  2. #2
    Join Date
    Apr 2004
    Location
    MN
    Posts
    1,818
    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.
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  3. #3
    Join Date
    Nov 2008
    Location
    Chapel Hill, NC
    Posts
    1,070
    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.

  4. #4
    Join Date
    Jun 2006
    Location
    Richmond, VA
    Posts
    2,944
    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

  5. #5
    Join Date
    Nov 2007
    Location
    NC
    Posts
    137
    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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