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Combustion air duct

zepfan Member Posts: 398
Does any one know if in NFPA 54, or the IFGC it lists the minimum gage metal needed for combustion air into a boiler room? The room in question has on 400 mbh boiler. I can’t find a minimum size listed. Thanks to all


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    I've only seen 24ga for a thimble listed as minimum.

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