How To Replace The Ignitor On A Gas Furnace

Posted on: 30 January 2015

A home can get cold quickly when your furnace breaks down in the middle of winter. One part that will break down every few years or so is the ignitor that heats up the burner on the furnace. The ignitor will deteriorate through normal usage and will have to replaced every 3 to 10 years – depending on the type of ignitor (silicon nitride ignitors last a couple of years longer than silicon carbide ones). Here is how you can replace the ignitor and get your house warm again.

You Will Need:

  • Replacement Ignitor
  • Screwdriver
  • Flashlight
  • Chalk/Crayon

Turn Off Power and Gas

Turn off the power and gas to the furnace before you start to work on replacing the ignitor. The furnace may keep on trying to turn on since the house is cold and you could get hurt. Turn the power off at the circuit breaker as well as the furnace control thermostat to be extra safe. Turn the valve to the "off" position on the gas line.

Remove Furnace Door

Take the furnace door off and set it aside. Some doors are screwed in, but others slide into a groove along the top of the furnace door opening. Set the door to the side.

Accessing the Ignitor

The ignitor can be found in one of two places. It will either be directly under the burners or it will be located in a sealed metal box by the burners. If it is under the burners, you can just unscrew it; but if it is in a metal box, you'll have to take the cover of the box off to get at the ignitor.

Removing Ignitor

You have to make sure you are placing the new ignitor into the same position that the broken one is in. Take a piece of chalk or brightly-colored crayon (it's usually hard to see inside the furnace, and you'll want to place markings so you can easily see them using a flashlight). Make sure you put markings on the old ignitor and on the housing where the new ignitor will go. Unscrew the ignitor from its housing unit and disconnect the power clip that goes to the ignitor. The ignitor should slide right out.

Replacement Ignitor

Put the markings on the new ignitor exactly like the marking you have them on the broken ignitor, Slide the new ignitor into the housing and match the markings up together. Screw the ignitor into place and reconnect the power clip to the ignitor.

Turn on Gas and Power

Replace the furnace door. Turn the circuit breaker and turn the gas back on. Go to the thermostat panel, switch the furnace on, and turn the heat up. The furnace should kick on within a minute or two.

For more information, contact All Heating Services or a similar company.