Furnace hot surface igniter kit. The igniter gets very hot and glows bright orange to light the gas burner. If the igniter is cracked or defective, the furnace won’t heat.
Furnace flame sensor. The flame sensor monitors the burner to detect whether or not a flame is present. If the flame sensor is defective, the furnace may not heat.
Furnace control board. The control board regulates the supply of power to the furnace components. Be sure to check more commonly defective parts before replacing the control board.