Definition of the term Flue Damper
An automatic door located in the flue that closes it off when the burner turns off; its purpose is to reduce heat loss up the flue from the still-warm furnace or boiler.
Total House Inspection Blog
An automatic door located in the flue that closes it off when the burner turns off; its purpose is to reduce heat loss up the flue from the still-warm furnace or boiler.