Furnace Parts Names and Functions — Complete Guide
Published: July 22, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC
Main Furnace Components
Heat exchanger: transfers heat from combustion to air. Burners: where gas burns to create heat. Ignitor: lights the burners (hot surface or spark). Flame sensor: confirms the flame is present. Gas valve: controls gas flow to the burners. Blower motor: drives the fan that circulates air. Blower wheel: the fan that moves air.
Safety and Control Components
Limit switch: shuts off burners if heat exchanger overheats. Pressure switch: verifies the inducer motor is creating proper draft. Inducer motor: pulls combustion gases through the heat exchanger and out the vent. Control board: the brain that controls all furnace operations. Transformer: converts 120V to 24V for thermostat and controls.
Air Distribution Parts
Air filter: captures dust and debris. Supply plenum: distributes heated air to ducts. Return plenum: collects return air from the home. Ductwork: carries air throughout the home. Registers: vents where air enters rooms. Return grilles: vents where air returns to the system. Humidifier: adds moisture to the air.