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Fresh Air

I am installing a 45,000 BTU   %80 furnace in a small mechanical room in a finished attic and would like to bring in fresh air for combustion. Is there a calculation to find out what size pipe I need? Thanks, Mike


  • Tim McElwainTim McElwain Member Posts: 3,904
    Do you have a copy

    of NFPA 54 National Fuel Gas Code? If so look in the "Air for Combustion" section. There should also be something in the I & O manual for the furnace.
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