Definitions for "Combustion Air"
Keywords:  furnace, heater, appliance, fuel, duct
(HVAC) The duct work installed to bring fresh, outsiede air to the furnace and/or water heater.  Normally 2 supplies of air are grought in.  One high and one low.
Air used in the combustion process. Air contains oxygen which is required to combust fuel.
Air that provides the necessary oxygen for complete, clean combustion and maximum heating value.