Burning smell when you turn on the heat: normal or not?
The first cold night in Danville, you turn on the heat, and the house smells like something's burning. Usually it's harmless. Sometimes it isn't. Here's how to tell the difference.
Smell gas (rotten eggs), or a carbon monoxide alarm is sounding? Don't use light switches or phones inside. Get everyone outside, then call 911 or your gas utility from outside.
The dusty smell on the first cold day
Over the warm months, dust settles on the furnace's heat exchanger, burners and heat strips. When the heat comes on for the first time, that dust burns off and you smell it through the vents.
HVAC manufacturer Trane says to let the unit run for about 10 minutes. If the smell fades, the system is likely fine. If it persists or gets worse, turn the system off and call a professional. Trane also says a burning smell that lasts more than an hour points to a bigger problem (Trane).
The same thing happens with heat pumps, which have electric backup heat strips that collect dust over the summer.
Help it along: change the air filter before the first cold snap, and vacuum around the furnace and return vents.
Smells that mean stop
| Smell | What it may mean | What to do |
|---|---|---|
| Rotten eggs or sulfur | Natural gas leak. Utilities add the smell so leaks can be noticed. | Get out now. Call 911 or your gas utility from outside. |
| Burning plastic, rubber or hot wires | Electrical problem, overheating motor or wiring | Turn the system off at the thermostat and breaker. Call a technician. Trane calls this a sign of a possible "severe electrical problem." |
| Burning smell that lasts over an hour | Something more than dust, such as an overheating part or a foreign object | Turn it off and call a technician. |
| Musty or moldy | Dirty filter, or moisture and mold in the system or ducts | Replace the filter. If it continues, have the system checked. |
| Chemical smell on a brand-new furnace | Coatings burning off new parts | Trane suggests ventilating and running it a few hours. If it doesn't fade, call the installer. |
Carbon monoxide: the danger you can't smell
Carbon monoxide (CO) has no smell, so a working alarm is the only warning. The U.S. Consumer Product Safety Commission says early CO poisoning symptoms are similar to the flu but without a fever: headache, fatigue, shortness of breath, nausea and dizziness (CPSC).
The CPSC recommends:
- A CO alarm in the hallway near the bedrooms in each sleeping area of the home
- A professional inspection of all fuel-burning heating systems every year, including chimneys, flues and vents, checks for gas leaks, and adequate ventilation
If several people in the house feel sick at the same time, feel better when they leave, or pets seem ill too, treat it as a possible CO problem. Get everyone outside and call 911.
Before you call
- Change the filter if it's dirty. A clogged filter makes systems run hot.
- Look and listen. Note where the smell is strongest, and whether you hear squealing, grinding or clicking.
- Don't keep restarting it. If an electrical smell came back after a reset, leave it off.
Time for a tune-up?
If you haven't had the heating system checked this year, now is the time. A heating tune-up before winter is the best way to catch cracked parts, loose wiring and venting problems early. See HVAC maintenance and furnace repair.
Tell us what you're smelling and where you are in Danville or Pittsylvania County. We'll connect you with a local HVAC company. It's free.