How to Replace a Gas Furnace Ignitor

inside of a gas furnace
What You'll Need
Screwdriver (according to the furnace model)
New furnace ignitor
Flashlight (optional)
Gloves (optional)

A gas furnace ignitor is used to start up the furnace and it uses an electric current and a filament to ignite. The system used depends on how old the gas furnace is, but normally nowadays we use the electric ignition with the hot surface system. An electric current is passed through the wire that produces enough heat to generate a spark to fire up the main furnace burner. An ignitor made out of silicon carbide can last from three to five years while an ignitor made up of silicone nitride has an expected lifespan from six to 10 years.

So gas furnace ignitors aren’t infallible and need to be replaced after some considerable amount of use. Changing the ignitor isn’t a hard job but you will need to work with patience because if not you’ll cause more damage to the gas furnace. Usually this is a one-person job.


Before starting work on your gas furnace ignitor always switch off the electric power and cut off the gas source. Use appropriate equipment and safety gear, and work in a safe environment; that is, in a well ventilated room. Make sure that the room is well lit to work more comfortably.

Step 1 - Locate the Ignitor

Usually the ignitor is found near the center of the burners but if it's not there then it’s probably in the sealed burner compartment. If it’s in the sealed compartment, then you have to disassemble the covers to get to the ignitor. Whatever the case may be, it's not a tough job to do.

Step 2 - Remove the Ignitor

gas furnace

Once the ignitor has been located, you will have to unscrew it from its place. Try to loosen the screws a little bit at first to see if the ignitor budges. If that does work just unscrew them to the end and store them somewhere you would remember. It is of utmost importance to take note of the location of the ignitor so that you won’t have any trouble fitting in the new ignitor.

Hint: Take a few photos with your cell phone to refer to later.

Step 3 - Screw on the New Ignitor

Position the new ignitor and screw it in. Remember to tighten the screws well. If there were any covers, replace them. The last thing to do is to turn the power back on and insert the gas source. If you see the ignition glow then you’re done.

Tip: Take the broken ignitor to the parts shop so they can give you an exact replacement for your gas furnace. Obviously all brands have their own type of furnace systems but the replacement procedures are usually the same or very similar.