Max Appliance Input from Room Volume
Largest appliance BTU input a confined space supports by the standard volume method.
Example
You enter
- Room volume (ft³) 4000
You get
- Max appliance input (by volume) 80000
- Max kbtu input 80
Checked against published worked examples from: ICC.
Details, formula, and sources
ScopeBefore combustion-air openings are required (the inverse of Combustion Air).
Formula or tableStandard volume method solved for input (inverse of combustion-air): max appliance BTU/hr = (room_volume_ft3 / 50) * 1000, since IFGC 2027 §304.5 treats a space as adequate at 50 ft^3 per 1000 BTU/hr.
Source and editionIFGC 2027 (International Fuel Gas Code) / NFPA 54. §304.
Free accessFree read-only access at codes.iccsafe.org.
What governsEstimate. AHJ and licensed mechanical contractor govern. ACCA Manual J / D / S supersede rules of thumb.
API field namesroom_volume_ft3, max_btu_input, max_kbtu_input
- Standard method IFGC §304.5 volume rule; above the returned input the space is confined and needs openings, or use the known-air-infiltration-rate method (§304.5.2), or outdoor openings (§304.6)IFGC 2027