Gas equipment shall not utilize combustion air or ventilation air from which spaces?

• A. Kitchen
• B. Bedroom or bathroom
• C. Garage
• D. Living room

Answer: (B)

The gas appliance needs a clean, adequate supply of combustion air, and that air should not come from spaces designed for human occupancy. Bedrooms and bathrooms are typically small, tightly sealed rooms that may have exhaust fans or other ventilation that can create negative pressure, pulling combustion products back into living areas or starving the appliance of the air it needs. By prohibiting combustion air from spaces like bedrooms and bathrooms, the code helps prevent backdrafting and the entry of combustion byproducts (including carbon monoxide) into areas where people live and sleep.

Other spaces such as kitchens, living rooms, or garages are also not ideal sources in some situations, but the standard highlights bedrooms and bathrooms because they are common, enclosed occupancy spaces where relying on indoor air can more readily lead to unsafe conditions.