Furnace Burning Smell: Dust, Electrical or Gas?

A dusty, burning smell for the first hour after you turn the heat on in the fall is usually dust burning off the burners and heat exchanger. It should fade the same day. A hot electrical or plastic smell, a smell that keeps coming back, or a rotten-egg smell is different: shut the furnace off, and for rotten eggs, leave the house.

What the Smell Usually Means

The First Cold Day of the Year

Almost every furnace smells a little when it runs for the first time in the fall. Over the summer, dust settles on the burners and the metal that heats your air. The first few cycles burn it off. If the smell is gone by the end of the day, there’s nothing to fix.

If it hangs around for days, pull the filter. A packed filter starves the furnace of air and makes it run hotter, which can bring the smell back every cycle. Our filter and airflow guide explains sizes and how often to change it.

Electrical or Plastic Smell: Turn It Off

A sharp, hot-wire smell usually comes from the blower motor, its capacitor or a wire that’s getting too hot. A motor that is struggling can also hum or run slowly before it fails.

1. Set the thermostat to off.
2. Turn the furnace off at the switch beside it (it looks like a light switch) or at the breaker.
3. Don’t take panels off or try to find the part yourself.
4. Call and describe the smell, when it started and whether you heard humming or a change in the fan.

For more on motor faults, see blower motor problems.

Rotten Eggs: Leave First

Natural gas has no smell of its own. FortisBC adds the rotten-egg odour so a leak is obvious. If you smell it, FortisBC’s advice is to stop what you’re doing, leave the building and leave the doors and windows as they are. Don’t use your phone, light switches or anything that could spark inside. Call 1-800-663-9911 or 911 once you’re outside. FortisBC handles the leak; call us after it’s safe.

When to Call Us

• The smell lasts more than a day
• It’s electrical, plastic or rubber
• It comes with a new noise, a tripped breaker or the furnace shutting down
• You notice headaches or feel unwell at home and better outside (leave and call 911 or FortisBC first)

Questions About Furnace Burning Smells

Is a burning smell normal when I first turn on the furnace?

Yes, a dusty burning smell for the first few hours of the season is usually dust burning off the burners and heat exchanger. If it lasts more than a day or smells electrical, turn the furnace off and call.

What does an electrical burning smell from a furnace mean?

Usually an overheating blower motor, capacitor or wire. Turn the furnace off at its switch or breaker and have it checked before running it again.

What should I do if my furnace smells like rotten eggs?

Treat it as a gas leak. Leave the house without using your phone or light switches inside, then call FortisBC at 1-800-663-9911 or 911 from outside.

Can a dirty filter make the furnace smell?

Yes. A clogged filter makes the furnace run hotter and can bring back a burning-dust smell every cycle. Replace it and see if the smell goes away.