Combustion Air

Required combustion air opening from BTU input and room volume.

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Formula and source

Required combustion-air opening per IFGC 2021 §304 (standard method): 1 sq inch per 1000 BTU/hr for outdoor air, 1 sq inch per 4000 BTU/hr for indoor air with two openings.

IFGC 2021 (International Fuel Gas Code) / NFPA 54. §304.

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