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How to Replace a Furnace Ignitor

Is Your Furnace Failing to Ignite?

When the temperature drops and your furnace refuses to kick on, the culprit is often a faulty ignitor. This small but critical component is responsible for lighting the gas burners in your heating system.

A glowing ignitor is the heart of the combustion process. If it cracks or wears out, your furnace will attempt to start but fail to produce heat, often resulting in a lockout.

In this guide, we will walk you through the steps to safely replace your furnace ignitor. If you feel uncomfortable working with electrical components, you can find trusted professionals through HVACDatabase.com to handle the job for you.

Signs of a Bad Furnace Ignitor

Before you start pulling panels off, look for these common symptoms of ignitor failure. If your furnace clicks and the blower runs, but you see no orange glow near the burners, the ignitor is likely dead.

Sometimes the furnace will try to ignite three times before shutting down. During this time, it may display a specific light pattern on the control board. You can learn more about identifying these flashes by reading our guide on how to troubleshoot a furnace error code.

Tools and Materials Needed

Replacing an ignitor is a relatively simple DIY project that requires only a few basic tools. Having these ready will make the process much smoother.

  • A new replacement ignitor (match your furnace model number)
  • A 1/4-inch nut driver or a multi-bit screwdriver
  • Latex or nitrile gloves (crucial for handling the new part)
  • A multimeter (optional, for testing)

Step 1: Turn Off the Power and Gas

Safety is the top priority when performing any HVAC repair. Locate the power switch on the side of your furnace or the dedicated breaker in your electrical panel and flip it to 'Off'.

Next, close the gas shut-off valve leading to the furnace. Even though the ignitor is an electrical component, working near gas lines requires total isolation of the system. You might also want to ensure your safety sensors are functional by learning how to test your carbon monoxide detector before restarting your unit.

Step 2: Access the Burner Compartment

Remove the upper service panel of your furnace. Most modern units use thumbscrews or standard hex-head screws to hold the panel in place.

Locate the ignitor, which is usually positioned near the first burner tube. It will have two wires leading to a plastic wiring harness or the control board.

Step 3: Remove the Old Ignitor

Carefully disconnect the wiring harness by squeezing the plastic tabs and pulling them apart. Use your nut driver to remove the screw securing the ignitor bracket to the furnace frame.

Gently pull the ignitor out. Inspect the element; if you see a small black smudge or a visible crack in the grey silicon carbide, the part is definitely blown. If it looks physically intact, you may want to check other issues like how to check your furnace gas pressure if ignition remains inconsistent.

Step 4: Install the New Ignitor

This is the most critical step: Do not touch the black or grey element of the new ignitor with your bare hands. Your skin produces natural oils that create a 'hot spot' on the ignitor, causing it to shatter the moment it heats up.

Slide the new ignitor into the mounting hole and secure it with the screw. Reconnect the wiring harness until it clicks into place. If you are also dealing with wiring issues elsewhere in your home, check out our tips on how to wire a thermostat.

Step 5: Test the System

Once everything is secure, put the service panel back on. Turn the gas valve back to the open position and flip the power switch to 'On'.

Adjust your thermostat to call for heat and watch through the observation window. You should see the ignitor begin to glow bright orange, followed by the sound of the gas burners lighting up.

When to Call a Professional

If you replace the ignitor and the furnace still fails to stay lit, you may have a more serious issue, such as a clogged flame sensor or a cracked heat exchanger. Repairing these items can be costly; see our guide on the cost to repair a heat exchanger for more details.

In some cases, especially with older homes using boiler-based heat, you might be looking at a hydronic heating system cost guide to determine if an upgrade is better than a repair.

If you're unsure of your DIY skills, or if you need a specialized pro in a specific area, you can choose an HVAC contractor in Houston or any other city through the HVACDatabase.com directory. Our platform connects you with vetted experts who can get your heat back on quickly and safely.