Some furnace smells are normal and fade on their own. Others mean you should shut the system off or leave the house. Here’s how to tell them apart.
Rotten eggs or sulfur
Natural gas has an added smell like rotten eggs. Leave the house right away, don’t switch anything on or off, and call the gas utility (Enbridge Gas) or 911 from outside.
Dusty burning smell at the first cold snap
Usually normal: dust on the burners and heat exchanger burns off the first few times the furnace runs in fall. It should fade within a day. If it doesn’t, have it checked.
Electrical or burning plastic
Turn the furnace off at the switch or breaker and call. It can mean an overheating motor or wiring.
Exhaust or fuel smell
Can mean a venting problem that lets combustion gases into the home. Turn it off, open windows, and call. Make sure your carbon monoxide alarms work: carbon monoxide and furnace safety.
Musty smell
Often moisture in the ducts, a dirty coil or a blocked condensate drain. Indoor air quality · UV-C coil lights.
Help
Our emergency line is answered live 24/7 at (385) 250-0687. Inside West Valley City limits, Monday–Saturday 8 AM–5 PM, we guarantee a technician within 45 minutes of answering your call, or the emergency inspection is free (terms).
Frequently asked questions
Is it normal for a furnace to smell when first turned on?
A dusty burning smell during the first runs of the season is common and should fade within a day.
What should I do if I smell gas?
Leave the house immediately, don’t operate switches, and call Enbridge Gas or 911 from outside.
What does a burning plastic smell from the furnace mean?
Possible overheating motor or wiring. Turn the furnace off and call a technician.