Furnace Not Igniting? A NJ Tech Explains What to Do | Air Experts

Having trouble getting your furnace to ignite? That’s the last thing you want to deal with during the NJ winter. 

But before we dive into why your furnace isn’t igniting, we want to be clear: there’s a difference between a furnace that won’t ignite and a furnace that just won’t start at all (in this blog, we’ll only be looking at why your furnace won’t ignite).

If your furnace is struggling to ignite, you’ll likely hear a clicking noise at the thermostat and at the furnace, signifying that the thermostat is sending a call for heat, and the furnace is trying to ignite. 

If you don’t hear any noise, your furnace likely isn’t starting at all. There are a variety of reasons your furnace won’t start, and we would suggest reaching out to a technician for help. 

However, if your furnace is starting, but just won’t ignite, you’ll need to check:

  • The air filter
  • Gas line 
  • Ignition source

Below, we’ll look at each of these in more detail, so you know why your furnace won’t ignite and what to do to get your furnace working again. 

Tip #1: Check the air filter

In order to ignite, your furnace needs a specific mixture of gas and air. If your air filter is dirty or clogged, it can block airflow to your system. If airflow is blocked, this can disrupt the ratio of gas to air and prevent your furnace from igniting. 

To see if this is your issue, check your air filter. If it looks like the filter on the right, it’s time to replace it. 

Note: If your filter was dirty, give your furnace a little time to catch back up. If your furnace is still struggling to ignite after an hour or so, it’s time to call a professional.  

Tip #2: Check the gas line

As we mentioned above, your furnace needs the right mixture of gas and air to light, and if there is an issue with the gas flow, your furnace won’t ignite.

To check your gas flow, go outside and ensure that the valve is turned on. Another easy way to determine if gas flow is your issue is to turn on another gas appliance like your stove. If the gas to your stove turns on, then gas flow to your home is likely not your issue. However, there could still be an issue with gas flow to your furnace. Check the furnace’s gas line valve and ensure that it’s on (the valve handle should be parallel with the gas line).

If your main gas line valve and your furnace gas valve are both on, call a professional to come and take a look. 

Warning: If you smell gas around your furnace but your furnace is not igniting, you should call a professional immediately. A gas leak is a potentially very dangerous situation and isn’t something you should wait on handling.  

Reason #3: Check the ignition source

If you’ve checked all of the above and you are still having issues with your ignition, the issue is probably with your ignition source.

If you have an older furnace (20 years +), your ignition source will likely be a pilot light.

If your pilot light is out, you can try to relight it, BUT if you have already tried to re-light your pilot light and your furnace is still struggling, you should call a technician.

To relight your pilot light…

  1. Turn the pilot light dial to the OFF position and wait at least 5 minutes. This is usually located near the bottom of your furnace. 
  2. After waiting 5 minutes for the gas to dissipate, turn the switch to Pilot and hold down the reset button. While you are holding the reset button, turn on a long lighter and hold it near the pilot light opening. 

If you have a newer furnace, the ignition source will be an electronic furnace ignition (hot surface ignition and an intermittent pilot).

To check to see if your electronic ignition is working, look under your furnace or remove the front panel of your furnace. If you see a glow when your furnace is trying to turn on, your igniter probably isn’t the issue. If you don’t see a glow, or if you hear repeated clicking noises when your furnace is trying to turn on, you probably have an issue with your ignition.

If your furnace has an electronic ignition source, our suggestion would be to call a technician to come to check it out and fix it. Igniters are very fragile so we wouldn’t suggest trying to repair or clean them on your own. 

Still having issues with your furnace? Hire the best in NJ: Air Experts

If you are still having issues with your furnace, we are happy to help. We have over 25 years of experience serving NJ homeowners, so regardless of your furnace issue, we would be happy to help you diagnose the issue and repair your furnace.    

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