A draft inducer motor is a small fan motor that creates negative pressure in a furnace combustion chamber before ignition, removing hazardous gases and ensuring proper air-fuel mixing. This motor operates at the beginning of the heating cycle and must run for 15-30 seconds before the igniter can energize. Draft inducers are mandatory safety components in sealed-combustion and condensing furnaces.
Operating Function
The draft inducer motor typically runs at 3,450 RPM and moves 150-300 cubic feet per minute of air through the heat exchanger and exhaust vent. The motor energizes before ignition sequence begins and includes an integral pressure switch that confirms adequate airflow. If airflow is insufficient, the pressure switch prevents ignition, protecting against dangerous combustion conditions.
Maintenance and Troubleshooting
Draft inducer motors are sealed units with lubricated bearings designed for 15-20 year service life. Common failure points include bearing wear, motor coil burnout, and pressure switch malfunction. Blocked venting, bird nests, or ice formation can prevent adequate airflow and trigger system lockout. Annual inspection of vent pipes and motor operation ensures reliable furnace startup during heating season.