The Lifespan of a Furnace Igniter

Process

• Electricity passes through the igniter when the thermostat calls for heat, making it glow red-hot. When the nearby flame sensor detects this glow, it opens the main burner valve. The gas that’s released from the valve lights when it hits the hot surface of the igniter, and the furnace starts producing heat. Over the course of a single heating season, the igniter can turn on and off thousands of times.

Failure

• Furnace igniters can fail for several reasons aside from normal aging. Dirty igniters can short out when the thermostat calls for heat. Igniters can also fail if you have high home line voltage. Check your voltage and have your electric company put a transformer on your line if you have anything over 125 volts. Handling the igniter incorrectly and allowing oil from your skin to get on the gray glass part of your igniter can also cause premature failure. Bumping the ceramic part of the igniter can cause it to crack. Even a hairline crack will keep your igniter from working.

Replacing

• Turn the power to the furnace off before you replace the igniter. Look for a plastic plug and socket and disconnect the igniter wires that you find there. Remove the mounting screws next and the take the igniter out. After installing the new igniter and replacing the screws, you can reconnect the wires and turn the power back on. Observe a complete heating cycle to ensure that everything is working properly.

Cost

• A furnace repair technician can replace your igniter for you if necessary, for a cost of around $150 at the time of publication. You may also be able to replace the igniter yourself. Furnace igniters cost between $25 and $50, depending on the make and model of your furnace. If you own a standard igniter that you’ve had to replace several times, you might want to upgrade to a silicon nitride igniter, which is more durable. Silicon nitride igniters use a different kind of ignition control but an upgrade kit is available for around $30.