What Causes Frequent Furnace Ignitor Failure?

Damaged

• Most furnaces use a hot surface ignitor because they’re inexpensive and reliable. However, they won’t work if they’re cracked. If your furnace goes into lockout mode because the burners don’t ignite, try resetting it by turning the power switch to the furnace off and back on again. If the furnace still fails to light, turn off the power and gas to the furnace and remove the ignitor. Inspect it for cracks. If it’s not cracked, the ignitor is still good.

Dirty

• If your ignitor is dirty, it can short out when the furnace calls for heat. A dirty filter or squirrel cage can also cause your ignitor to keep going out by making your furnace cycle too much. This causes the high limit switch to kick in and shut your furnace down so it doesn’t overheat. A dirty air conditioning evaporator coil causes the same problem. If your furnace comes on for eight or ten seconds and then shuts off, try cleaning your flame sensor with an emery cloth or light sandpaper.

High Voltage

• Another reason why your ignitor can fail is if your house has high line voltage. Check your voltage, and call your electric company if your reading is over 125 volts. The electric company can put a transformer on your line to reduce the voltage.

Age

• Ignitors have a life span of three to ten years depending on the type. Silicon carbide ignitors usually last three to five years and silicon nitride ignitors can last up to ten years. Eventually, they will crack and will need to be replaced. A new ignitor costs between $25 and $50 at the time of publication, depending on the make and model of your furnace.

Other

• Other reasons why your furnace ignitor might need frequent replacement include installing the wrong ignitor for your furnace or allowing oil from your skin to get on the element. You should never touch the gray glass part of your ignitor. High gas pressure can also be a problem by causing the furnace to cycle too much and overheat. One sign that your gas pressure might be too high is if your furnace sounds like a jet when it’s running. In this case, have an HVAC technician adjust your gas valve.