An Inducer motor is a small single phase motor located inside the gas furnace of your heating system. It has a blower connected to each end. One blower functions to cool the motor during its operation and is usually made from plastic and is visible when you open the furnace door. The second blower is for pulling heat from heater burners, in conjunction with the heat exchanger out to the vent pipe.
The inducer motor is an integral part of any furnace and its failure will lead to numerous problems with your heating system. We will first look at the normal operation of the induced motor before we get to diagnosis and replacement.
Normal Operation of Induced Motor
The inducer assembly is comprised of a small fan pulling air through your furnace heat exchanger and sending out through the vent pipe. For larger furnaces, the fan is usually made from metal while smaller motors have plastic fans.
The inducer will establish a draft through in conjunction with furnace and at times may be referred to as draft inducer. The inducer motor is powered from a 120vac or 240vac through the furnace control board. The control board will provide power to the inducer during normal operation of the furnace.
The inducer acts to control the furnace pressure switch through a rubber hose. When the inducer begins to run, the pressure switch is closed as a result of fan suction. This pressure switch has an extra hose connected to the outlet of the fan. Once the pressure switch is closed, the furnace control operates with the normal heat cycle and your furnace will work normally.
However, if something is plugged in to the vent pipe, the pressure emanating from the fan will make the pressure switch open.
Inducer Assembly Replacement
It is paramount to carry out a few troubleshooting on your inducer assembly before you decide to call a dealer to do the diagnosis and replacement. Just by following these easy tips, you could save hundreds of dollars you would spend on professional dealers.
Finding the problem
You should first verify the working condition of the inducer assembly prior to replacement.
If the inducer motor operates by starting on ignition but the furnace fails to complete the ignition sequence, then the problem could be clogged vent pipes or condensate in within the inducer assembly. Condensate may fill up or clog the inducer assembly causing the ignition to fail or delay causing fatal bangs.
If the inducer motor fails to start as required, you should try feeling the motor with your hands to check if it is hot. A hot inducer motor indicates a failure and the motor should be replaced. Check with your furnace or motor dealer for a genuine replacement.
If the motor is not hot, you may check the power supply to your motor. If the electric power is not reaching the motor, check whether the thermostat is calling on the furnace to come on. If it doesn’t, you should check the thermostat settings before you think of servicing or replacing the panel.
Inducer Assembly Replacement Procedure
Begin your inducer motor replacement by turning off the supply to the motor and ensuring the furnace is turned off. You should check that the furnace has cooled down enough to begin working on the motor. Start by marking the hoses and writing down where they link on the inducer.
You should then mark all the wires and note down the terminals they connect to. For some inducers, the work may be simpler as they will come with socket and plug connectors, while others will not. You will have to go the longer root of marking all the wires to avoid trouble of connecting wrong wires in the wrong ports.
Next, disconnect the vent pipe followed by the condensate drain tube, usually on larger units.
Then, unscrew the inducer assembly mounting to remove the assembly from the furnace.
Now replace the assembly with the new unit in to the furnace and screw back in position. You may need high temperature silicon to seal it and always ensure the gasket is installed. For larger units, you will find a rubber gasket attached.
Then you can reconnect back the wires following the marks, and then connect back the pressure switch hoses, followed by condensate drain tube. You then reconnect the vent pipe.
Finally complete the induced motor replacement by switching back the power to the furnace. Observe the operation over a complete heating cycle to confirm proper operation.