Fuel-burning appliances require dedicated combustion + dilution air (indoor air method ≤ 0.40 ACH; otherwise outdoor air)

Description

Fuel-burning appliances (gas furnaces, water heaters, boilers, ranges) need air for combustion + dilution of flue gases. The indoor air method satisfies the requirement when the appliance space has a known infiltration ≤ 0.40 ACH (G2407.5). Otherwise, outdoor air must be introduced via methods in G2407.6 through G2407.9 — typically high + low openings to the outdoors, or a single opening sized per the appliance input rating. Direct-vent and mechanical-draft Category III/IV appliances are exempt (they bring their own combustion air through sealed pipes).

Why this exists

Tightly-built homes starve atmospheric gas appliances of combustion air; the result is spillage of flue gases including CO into the home. Architects designing high-performance homes should default to direct-vent appliances (sealed combustion) to eliminate the issue entirely. Closet-installed water heaters frequently fail combustion-air checks — preflight the closet ACH or specify direct-vent.

Measurements

Categories

Applies to

• Jurisdiction: New York State

Source

Solver enforcement

Browsable only — the solver does not currently enforce this directive (no spec-level data to check against). This entry exists so the architect personas can cite it in conversation and the user can read what the rule says.

Related directives

• Garage / dwelling fire separation · IRC R302.6
• Natural light in habitable rooms · IRC R303.1
• Habitable space minimum ceiling height · IRC R305.1
• Egress window net opening dimensions · IRC R310.2
• Stair riser, tread, and headroom · IRC R311.7