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Electric Furnace Not Igniting? 4 Common Causes + What To Do

If your electric furnace isn’t igniting, you’ll be left with a frigid home. Although electric furnaces are a modern heating solution, they’re not without their problems.

Your electric furnace isn’t igniting because of dead thermostat batteries, bad thermostat wiring, a faulty ignitor, or a clogged air filter. You can fix the problem by ensuring the thermostat is working correctly, the ignitor creates a spark, and by replacing or cleaning the air filter.

This guide will go over the most common reasons your electric furnace isn’t igniting and how to fix each problem.

Dead Thermostat Batteries

We should start with issues that you can diagnose without opening up the furnace. This means taking a closer look at the thermostat. 

The thermostat tells the furnace to ignite or increase heat. So, when the thermostat is dead, it means you’ve lost all communication with the furnace. If you take a peek at the furnace, you’ll find that it’s ice cold.

Thermostats can either run on direct power from the HVAC system or run on batteries. If you’ve opted for a thermostat that runs on batteries, you have to replace them fairly often. Maybe the batteries are dead or close to it. When they are, the thermostat has no power. This means any settings you configure on the thermostat will yield no changes in temperature.

How To Fix

Changing the batteries in the thermostat is by far the easiest of all fixes. This is why we recommend starting with this step. The most important part of this fix is to ensure you get the right batteries:

  1. Remove the thermostat from its wall mount
  2. Look for a battery panel on the back of the device. 
  3. Remove the panel. 
  4. Replace the batteries and reinstall the thermostat.

If you don’t know how to find and replace the thermostat batteries, watch this video: 

Bad Thermostat Wiring

Suppose the thermostat comes on but doesn’t send a signal to the furnace. There’s a chance that the problem lies with the wires. There are a few wires running from the furnace, and the thermostat needs them to communicate with it.

Unfortunately, a wire can break at any point where it runs, so you need to walk along the wireline to see where the problem is. A good idea would be to use a multimeter. You can check if there’s a drop in voltage at any specific point throughout the line. 

The wire may be bent, damaged, broken, or is missing insulation.

How To Fix

You need to inspect both ends of the wire to see if there are signs of damage:

  • Check the insulation. If it’s broken, it can cause a short circuit.
  • Use a multimeter. Check if there are broken or bent parts that lose signal.
  • Replace the wire. If the wire isn’t sending a clear signal, replace it completely instead of trying to fix it. Wires are cheap; the only difficult part is fishing them through the wall.

Faulty Ignitor

Electric furnaces use an ignitor to create a spark. The spark ignites the gas coming from the burners, heating up the air for your home. Depending on the type of electric furnace you have, the problem may lie with a faulty hot surface ignitor. 

This type of ignitor can run into problems when the interior of your furnace overheats. It could also be due to a crack or debris on its surface. When debris collects on the hot surface ignitor, it can’t create a spark, leading to a failed ignition. 

How To Fix

You first want to determine if the problem is related to damage or rather dirt. If the hot surface ignitor is dirty, clean it thoroughly. If the problem is caused by a crack or other damages, a replacement is your best way forward. Here’s what you have to do.

  1. Turn the furnace off and open it up. 
  2. Locate the hot surface ignitor. Don’t touch it with your hands; oils from your skin can damage the ignitor.
  3. Check to see if there’s a layer of debris on its surface. If this is the case, use fine sandpaper to clean it. 
  4. If you see a crack in the ignitor, take it out of the furnace and get a replacement. 

The video below will show you how to replace a hot surface ignitor:

Clogged Air Filter

People often associate dirty air filters with insufficient heating. But in some cases, this could be the reason your ignition is failing. The air filter improves the air quality in your home. Dust collects on the air filter over time. You should replace or clean the air filter every few months to ensure your furnace works optimally. 

When the air filter is clogged, it causes air to accumulate inside the furnace. When this happens, the furnace may overheat and trip the safety switch. The furnace can’t ignite if the safety switch has tripped.

How To Fix

Does your furnace use a reusable filter? If yes, remove it and run it under water. Make sure you get all debris and dust off the filter. Wait for the filter to dry before returning it to the furnace. Fasten the filter in its place and start up the furnace. 

If your furnace uses a disposable filter, get a replacement. Check what size your furnace uses to ensure you get a compatible filter. 


Clogged air filters, problems with the ignitor, and dead batteries are all issues that can cause a furnace not to ignite. Make sure everything is in good order before turning on your furnace again.

Hopefully, your furnace is now igniting, and the coziness of your home has been returned.


  • Chris Hewitt

    Chris is a Texas-based freelance writer who loves the outdoors and working in his garage. When he's not enjoying the Texas sun, he can be found tinkering with all sorts of things in his workshop.

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