Combustion Air

Combustion Air Ducts Must Be Approved and Kept Open

Can a combustion air duct run through an attic or crawl space?

M1702.4

Combustion Air Must Account for Exhaust and Depressurization

Can exhaust fans cause backdrafting of a water heater?

M1701.4

Combustion Air Openings Need High and Low Placement When Required

Where should high and low combustion air openings be located?

M1702.3

Confined Spaces Need Combustion Air Openings or Another Approved Method

How do I know if a mechanical room is confined or unconfined?

M1701.2

Engineered Combustion Air Systems Can Be Approved

Can an engineer design a different combustion air system?

M1703.1

Fuel-Burning Appliances Need Adequate Combustion Air

What is combustion air and why does my furnace or water heater need it?

M1701.1

Indoor Combustion Air Is Allowed Only When the Space Qualifies

Can combustion air come from inside the house?

M1702.1

Outdoor Combustion Air Openings Must Be Sized by Method and Appliance Input

How big do outside combustion air openings need to be?

M1702.2