The Draft Inducer and Operation of Gas Furnace Pressure Switch
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The Draft Inducer and Operation of Gas Furnace Pressure Switch The draft inducer motor is a blower that creates a flow of combustion air through the furnace's heat exchanger(s) to make sure all combustion exhaust byproducts are vented outside the home by the flue vent. During combustion the combustion blower creates an air pressure that is less than atmospheric (negative) between the inlet side of the combustion blower and the inside of the burner box of the furnace. The pressure switch which is normally open senses the drop in pressure and closes to complete the circuit. The proper degree of negative pressure differential is necessary to maintain furnace operation. When abnormal conditions exist such as such as draft inducer motor failure, restricted intake air vent, restricted combustion air vent, leaks around assemblies, or clogged condensate drainage, then sufficient differential pressure will not exist and the pressure switch will open and shut down the furnace. |