Why Does My Heater Smell Like Burning?

If your heater smells like burning the first time you turn it on this fall, it's usually dust. Over the warm months, a thin layer settles inside your furnace or on your heat pump's backup heat strips, and it burns off once the system heats up. The smell should fade within an hour or so.

That said, a few burning smells are not normal. Here's how to tell the difference, and what to do about each one.

Why does my heater smell like burning the first time I turn it on?

Your heating system sits idle from spring to fall. During that time, dust collects on the parts that get hot: the burners and heat exchanger in a gas furnace, or the electric heat strips in a heat pump's indoor unit. The first time those parts warm up, the dust burns off and the smell travels through your vents.

In Northwest Metro Atlanta, this usually happens on the first chilly night in late October or November. It's one of the most common things homeowners ask about that week, and most of the time everything is fine.

How long should the burning smell last?

A dust smell should fade within the first hour or so of running the heat, and it shouldn't come back the next day. If it's still noticeable after a day, or it returns every time the heat kicks on, something else is going on and it's worth having a technician take a look.

Which burning smells are not normal?

• An electrical or burning plastic smell. This can point to an overheating motor or a wiring problem. Turn the system off at the thermostat and call for service.
• A rotten egg or sulfur smell in a gas-heated home. This can mean a gas leak. Leave the house without flipping switches, then call 911 or your gas company from outside.
• A smell that comes back every time the heat runs. Dust burns off once. A smell that keeps returning usually has another cause.
• Visible smoke from the unit or vents. Turn the system off, get everyone out, and call 911.
• A musty smell. This isn't a burning smell, but it's common in fall. It often means moisture in the ductwork or on the indoor coil, and it's worth a look during a tune-up.

Do heat pumps smell like burning too?

Yes. Most heat pumps in our area have electric heat strips that switch on as backup heat on cold mornings or during a defrost cycle. You may notice a brief dusty smell the first time those strips run each season, sometimes weeks after you first turned on the heat. Like a furnace, that smell should fade and not come back.

How can I cut down on the burning smell?

1. Change your air filter before you turn on the heat. A clogged filter restricts airflow and makes the system work harder.
2. Run the heat for the first time on a mild day with a window cracked, so the smell clears out of the house.
3. Vacuum your vents and returns, and keep the area around your furnace or air handler clear of boxes and storage.
4. Schedule a heating tune-up each fall. A technician cleans and checks the parts that collect dust, and catches small problems before the cold weather does. Our Aero 360 Plan covers this every year.

When should I call a pro?

Call us if the smell lasts more than a day, smells electrical, or comes back every time the heat runs. For a gas smell or visible smoke, get out of the house and call 911 first.

For everything else, call Aero Air Services at (888) 409-2376 or request service online. If you need repairs, see our furnace repair and heat pump repair pages. We show up. We clean up. We back our work.

Frequently asked questions

Is it safe to leave the heat on if it smells like burning?

If it's a faint dust smell that's fading, yes. If it's getting stronger, smells electrical, or you see smoke, turn the system off and call for help.

Can a dirty air filter cause a burning smell?

It can contribute. A clogged filter restricts airflow, which can make parts run hotter than they should. Replacing it is the first thing to try.

Should I ever smell gas when my heat comes on?

No. Natural gas has a rotten egg odor added so leaks are easy to notice. If you smell it, leave the house and call 911 or your gas company from outside.