How To Replace A Broken Ignitor On A Gas Furnace

Posted on: 24 March 2016

An ignitor is an important part of a gas furnace's burner assembly and takes the place of the older model pilot lights. Without an operable ignitor, the unit doesn't know when to allow more gas or have the heat required to warm that gas and your air. If your furnace has stopped putting out hot air, the problem might be a broken ignitor.

Replacing a broken ignitor isn't a difficult process if you have some time and do-it-yourself repair experience. If any step in the process makes you feel uncomfortable, call in heating contractors to replace the part for you and to perform some general maintenance on the furnace at the same time.

This tutorial assumes you already know for certain the ignitor is broken. If you're unsure, follow the steps to remove the ignitor and then test for continuity using a multi-meter. If the reading is zero or lower than the manufacturer's recommendation, you can proceed with replacing the ignitor.

Always turn off the power to the unit before working and check your owner's manual for any variant instructions specific to your unit's model.

Things You Need:

  • Owner's Manual
  • Screwdriver
  • New Universal Ignitor
  • Razor Knife or Sharp Scissors

Step 1: Remove the Old Ignitor

Remove the door to the combustion panel by either pulling on the latches or twisting the handles that hold the panel in place. Set the door off to the side in a safe spot.

Locate the ignitor using the owner's manual for assistance, if necessary. There should be two bunches of wires under the ignitor that come together at a connection point that resembles two plugs. Unhook the plugs or connectors from each other. Let the bottom plug drop down for now. The upper plug and wires will pull free when you remove the ignitor.

Unscrew the fasteners that are holding the ignitor in place. Pull the ignitor's filament free of its slot in the burner assembly. Remove the ignitor and its attached wires and lay the unit flat on a table for comparison purposes and part salvaging.

Step 2: Prepare the New Ignitor

The universal ignitor will come with wires attached that are longer than what you will need. Lay the new ignitor next to the old one and use the length of the old wires as a length guide. Trim off the excess wire using a pair of sharp scissors or a razor knife. Strip back a bit of the insulation near the ends of the remaining wires for better connecting.

Now go back to the old ignitor. You want to save that connector plug and some of its wires. Cut the wires a couple of inches away from the plug or connector and free that piece from the old ignitor.

Hold the ends of the connector wires against the ends of the new ignitor's trimmed wires. Use the connecting nuts that came with the new ignitor to join the two sections of wire together.

Step 3: Reassemble the Unit

Slide the filament end of the ignitor back into the slot in the burner assembly. Attach the fastening screw that holds the ignitor firmly in place. Attach the connector end to its mate that's still attached to wires within the furnace.

Put the combustion door back in place and reattach its fasteners. Restore power to the unit and check for functionality. Call in a service tech (such as one from A One Heating & Air Conditioning) if you still have no heat.