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A furnace ignitor is the small part that lights the gas in your furnace. When it wears out, the blower may run but the burners never light, so your home gets no heat. Most ignitors last several years, then crack or weaken. If yours has failed, our furnace repair in Belmont team can test it and replace it.
Key Takeaways
- The ignitor lights the burners. No working ignitor means no flame and no heat.
- Clicking with no flame or a furnace that tries, stops and tries again are the classic signs.
- Ignitors are fragile. Oil from bare fingers can make a new one crack early.
- Replacement is a small repair compared with most furnace problems, but it involves gas and line voltage.
- Annual furnace service catches a weak ignitor before it quits on a cold night.
What Does a Furnace Ignitor Do?
When your thermostat calls for heat, the furnace runs a short start-up sequence. First the inducer fan clears the burner area. Then the ignitor heats up until it glows bright orange. Next the gas valve opens, and the hot ignitor lights the gas. A flame sensor then confirms the flame is there, and the blower starts pushing warm air through your ducts.
If any step fails, the furnace control board shuts the gas off for safety. That is why a bad ignitor often looks like a furnace that “tries” to start and then gives up.
Older furnaces used a standing pilot light that burned all the time. Most gas furnaces made in recent decades use electronic ignition instead. That saves gas, because the furnace only burns fuel when it is heating your home.
Types of Furnace Ignitors
| Ignitor Type | How It Works | Where You Find It |
|---|---|---|
| Hot surface ignitor (silicon carbide) | Heats until it glows, then lights the gas | Many furnaces from the 1990s and 2000s |
| Hot surface ignitor (silicon nitride) | Same idea, but tougher and heats faster | Most newer gas furnaces |
| Spark ignitor | Makes a high-voltage spark, like a gas grill starter | Some furnaces and many boilers |
| Intermittent pilot | Sparks a small pilot flame only when heat is needed | Some older and mid-age furnaces |
Silicon nitride ignitors last longer than silicon carbide ones. When a technician replaces an older carbide part, a nitride version is often a good upgrade if it fits your furnace model.
Signs of a Bad Furnace Ignitor
A failing ignitor usually gives warning signs before it quits for good. Watch for these:
- The blower runs but the air is cold. The fan works, but the burners never lit.
- Clicking with no flame. Spark systems click again and again while trying to light.
- No orange glow. Through the small sight window, a working hot surface ignitor glows bright during start-up.
- The furnace tries three times, then stops. Many furnaces lock out after a few failed tries.
- A flashing error code. The control board light often blinks a code for ignition failure.
- Heat that works some days and not others. A cracked ignitor may still work when it is warm, then fail on cold starts.
These signs can also point to a dirty flame sensor, a bad gas valve or a tripped safety switch. That is why a proper test matters before buying parts. If the furnace will not start at all, our guide on a furnace not turning on covers the other causes.
How Do You Tell If You Have a Bad Ignitor on a Furnace?
Watch the ignitor through the sight glass during start-up. If it never glows, glows dim, or shows a crack or white spot, it is likely bad. A technician confirms it with a multimeter by measuring resistance and comparing it with the furnace maker’s range for that model.
For example, Carrier’s furnace ignitor guide lists one silicon nitride ignitor at 40 to 70 ohms when new at room temperature. Your furnace may use a different range, so the reading must be checked against your own model’s specs.
Why Furnace Ignitors Fail
Ignitors work at very high heat and cool down after every cycle. Over thousands of heating cycles, the material weakens. Here are the most common reasons they fail early:
- Normal wear. Every heat-up and cool-down adds stress.
- Touching the element. Skin oil creates hot spots that crack the ceramic.
- Dirt and dust. A dirty burner area and a clogged filter make the furnace run harder.
- Power problems. Surges or high voltage can burn out the element.
- Short cycling. A furnace that turns on and off too often wears the ignitor faster. Our post on furnace short cycling causes explains why that happens.
What to Check Before You Call
Some no-heat calls turn out to be a simple setting. These safe checks take a few minutes:
- Check the thermostat. Make sure it is set to Heat and a few degrees above room temperature. Replace the batteries if the screen is blank.
- Check the filter. A badly clogged filter can trip a safety switch. Replace it if you cannot see light through it.
- Check the furnace switch. The light-style switch on or near the furnace must be On.
- Check the breaker. Reset a tripped furnace breaker once. If it trips again, leave it off and call.
- Reset the furnace. Turn the power off for about five minutes, then back on. This clears a lockout so you can watch one more start-up.
- Watch the sight glass. Note whether you see a glow, hear clicking or see an error code. Share this with the technician.
Do not remove the burner cover or touch the ignitor. If you smell gas at any point, leave the house and call your gas utility from outside.
Still no heat? Call Gerald Griffin Heating and Cooling at (980) 277-5122. We answer 24 hours a day, and a cold house in January is exactly the call we are set up for.
Can You Replace a Furnace Ignitor Yourself?
Some homeowners do. But it is easy to get wrong. Ignitors are brittle and can snap during install. Many look alike but are not the same part. The wrong ignitor may fit the bracket and still fail fast because the voltage or resistance does not match your furnace.
There is also the safety side. You are working next to a gas valve and live electrical parts. The EPA carbon monoxide guidance names worn or poorly adjusted furnaces as a source of carbon monoxide, and it recommends a yearly professional inspection of your heating system. A technician who replaces the ignitor also checks the flame sensor, the burners and the venting while the panel is already off.
DIY vs Professional Ignitor Replacement
| Factor | DIY | Licensed Technician |
|---|---|---|
| Part matching | Guesswork if the model number is worn off | Matched to your furnace model |
| Testing | Usually skipped | Resistance and voltage tested |
| Other checks | None | Flame sensor, burners, venting, safety switches |
| Risk of breaking the new part | High | Low |
| Warranty | Part only, if any | Part and labor |
How Much Does a Furnace Ignitor Cost?
The part is usually the small piece of the bill. Carrier’s guide puts the part at roughly $20 to $150, and professional replacement at about $150 to $450 total, depending on the furnace and where you live. Your final price depends on the ignitor type, how easy it is to reach and whether other parts need attention.
If your furnace is old and needs several repairs at once, it may be worth comparing repair against replacement. The ENERGY STAR furnace guide notes that certified gas furnaces can be up to 16 percent more efficient than standard models. We will give you both numbers and let you decide.
How to Make a Furnace Ignitor Last Longer
- Change the filter on time so the furnace does not overheat and cycle too often.
- Book a yearly tune-up in the fall, before the first cold snap.
- Fix short cycling early instead of living with it.
- Use a surge protector on the furnace circuit if your area sees frequent storms and outages.
Our seasonal maintenance plan options are a simple way to get a fall heating check on the calendar every year.
Furnace Ignitor FAQs
What is the average lifespan of a furnace ignitor?
There is no single number. Life depends on the ignitor material, how often the furnace cycles and how clean the system stays. Silicon nitride ignitors generally outlast silicon carbide ones. Many homeowners first notice a weak ignitor after several heating seasons, often on the first cold morning.
How much does it cost to get a furnace ignitor replacement?
Expect the part to be a small share of the cost. Manufacturer data puts total professional replacement at roughly $150 to $450. Call us for a firm price for your furnace.
What is the most expensive thing to fix on a furnace?
A cracked heat exchanger is usually the most costly repair, followed by the control board, blower motor or inducer motor. An ignitor is one of the lower-cost repairs.
How often should a furnace be serviced?
Once a year, ideally in the fall. The EPA recommends an annual professional inspection of furnaces, flues and chimneys.
Can you replace a furnace ignitor yourself?
It is possible, but the part is fragile, easy to mismatch and sits next to gas and line voltage. A technician tests the old part first, so you do not pay for an ignitor you did not need.
Get Your Furnace Lighting Again
If your furnace clicks, tries and stops, or blows cold air, call Gerald Griffin Heating and Cooling at (980) 277-5122. Tell us what you saw through the sight glass, and we will bring the right ignitor for your model. Gerald has been licensed since 1996, and our team serves Belmont, Mount Holly, Gastonia, Cramerton and the rest of Gaston County, 24 hours a day. You can also schedule a furnace visit online.
Gerald Griffin Heating and Cooling Services
902 Belmont Mt Holly Rd
Belmont, NC 28012
Phone: (980) 277-5122
Hours: Open 24 hours
NC Heating Contractor License #32307