Why Does the Heater Smell Like Burning When First Turned On?

We can all agree that if you fire up a furnace that hasn’t run for quite some time, it will have a distinct smell. How can you tell if your heater is defective or just a matter of burning off some residue? There are several ways to figure this out. Here are some common causes of a burning smell when your heater first turns on, along with tips for correcting:

What causes a heater to smell like burning?

There are several reasons why a heater may smell like it is burning.

  • The air filter is clogged and needs to be changed or cleaned. This can cause the heater to become too hot and cause a burning smell.
  • During the off-season, your furnace will have dust build up on the heat exchanger or the heat strips, depending on which type of furnace you have. This is the most common cause of a burning smell.
  • A cracked heat exchanger can also cause an odor, but it is much less likely and difficult to notice.

Can the burning smell be avoided?

If the smell comes from your furnace overheating, then yes, it can. Keep a clean filter in your unit; it will help keep your furnace from creating an unpleasant smell.

If it is the first time you turn on your furnace for the heating season, then it is unlikely that anything you do will prevent the odor entirely. Have a company check that your home’s ductwork is appropriately sealed and there are no leaks. You can also make sure that you are using quality filters. The smell is usually caused by dust on your heat exchanger or heat strips, so using quality filters will help eliminate that problem.

Is it normal for your heater to give off the first time you turn it on?

Yes- it’s normal for your heater to give off the first time you turn it on. This is because the fan and heat exchanger need to warm up before they can do their job. But don’t worry about that smell: even if it smells like burning, it doesn’t mean there’s a fire. 

However, if the smell continues to stick around, or you notice smoke, you should immediately turn the power off to your system and call a professional.

Burning smells that you should be concerned about

The smell of burning can indicate that your heater is not working correctly or damaged. If you smell a strong burnt odor in your home when using the heater, you may need to get it checked out by an HVAC professional.

If your heater doesn’t turn on or runs but doesn’t heat properly:

  • Turn off the breaker and unplug the unit.
  • Watch out for smoke within your home. Although your unit will have a bit of a burnt dust smell the first time you turn it on for the season, it should not have any smoke.
  • If the burnt smell lasts a significant amount of time, there may be a problem.
  • If it smells like burnt electrical, you will want to turn off the power to your unit as quickly as possible and call a professional to check it out.

Does an awful smell mean that I have a cracked heat exchanger?

If the smell is coming from the heater, and it’s not getting any better after you turn it off and wait a few minutes, it could be a problem with the heat exchanger. A cracked heat exchanger can cause a burning smell because dirt or dust leaks into your home through the cracks. This can get into your air ducts, which can cause health issues for you and your family. If this happens in your home, we recommend scheduling an appointment with one of our technicians. We can come out to inspect for any damage and determine if immediate repairs are needed before continuing to use your heater. We also recommend that you have a properly working and tested carbon monoxide tester in your home. If you think that you have a cracked heat exchanger, then you should not, under any circumstances, run your heater until you have it checked by a professional.

What if my heater smells burning when turned on all the time?

If the smell of burning is always present and not just when the heater is first turned on, you may have a more significant issue. There are several things to look for that could cause this situation:

  • Smoke or fire
  • Mold and mildew
  • Corrosion in the heating system
  • Water damage

If the burning smell is constant, then you should call the professionals at Honest Air to inspect your unit immediately for safety.


A burning smell from your furnace may not always mean something is wrong, but it can always be concerning. That is why Honest Air is always ready to inspect your furnace and provide you with the peace of mind you deserve. Give us a call today!

Experiencing any of these problems or have other questions?

Call us today at 301-943-0833