If your furnace smells like burning, this can be completely normal the first time you turn it on for the heating season. Dust can be burned out after the furnace turns on again, if it accumulated in the system during the summer months, and the smell will go away relatively quickly.
However, not all burning odours are harmless. When there is an electrical burning smell, a strong gas odor, a smoky smell, or a burning odor that is recurring, it can indicate a problem that requires attention. Here's how to tell the difference and what to do when your furnace smells like burning.
Is a Burning Smell From a Furnace Normal?
If the smell persists long after the furnace has been started, intensifies or reappears again after the furnace has been operating normally, it is not necessarily dust.
If an odor persists, there may be a problem with the furnace overheat, furnace debris, an electrical problem, or another issue that requires inspection. If the odor is unexpected or pungent, it is best to turn the system off and find out the reason rather than just waiting for it to go away.
Types of Burning Smells and What They Mean
The exact smell can give you an important clue about what's happening. However, smell alone can't always tell you what's wrong. If the odor seems unusual, turn off the furnace and have it checked by a professional.
Dusty / Burning-Dust Smell
If your furnace smells like burning dust during the first use this season, that's probably the only thing. Dust may accumulate on or around components during resting periods and give off a temporary scent when the system is operated.
However, if the odor goes away after the first start-up and doesn't reappear, it is unlikely to be an issue. If a dusty smell persists, however, it is time to take a closer look.
Electrical or Burning-Plastic Smell
A burning smell from a furnace which is electrical is more concerning. It may be related to the motor overheating, the blower, the motor's insulation damage, or any other over-heating electrical part.
Turn the furnace off at the thermostat. If you can do so safely, also switch off the electrical furnace switch, as well, and don't switch the furnace back on, until it has been inspected.
Do not attempt to inspect or distinguish a burned wire, or open electrical compartments. Electrical problems can generate heat and possibly even be a fire hazard.
Gas or Rotten-Egg Smell
If your furnace smells like gas, take the problem seriously and look at it differently than you would a regular burning-dust. Natural gas is not normally odorous, but gas sent to homes is mixed with odorants to make it easier to detect a leak.
Never use a flame, electrical switch, or phone while inside the building. Also, do not try to fix the furnace. Evacuate the building and call your local gas company or emergency service from a safe place.
Do not re-enter the area until authorized to do so by the appropriate utility or emergency personnel.
Burning Rubber Smell
If the belt or other rubber or plastic part is in contact with a hot surface, it can release a burning rubber odor. Debris that has found its way into the furnace can also create an unusual odor when heated.
Shut down the system if the odor is strong, persistent or if there are unusual noises. A technician can find out if a component is over-heating or if there is something blocking the system.
Smoky or Wood-Smoke Smell
If a furnace does give off a smoky odor, it should not be overlooked. It can be caused by debris burning in the unit, but combustion or venting issues can also cause flammable combustion products to enter the house.
A leaking furnace heat exchanger can pose a serious safety threat because it allows combustion gases to leak into the air that is circulated throughout your home. EPA states that combustion products, such as carbon monoxide, can be introduced to the inside through cracked furnace heat exchangers and broken or blocked furnace flues.
If your furnace is flaming or if there is a smoky or burning smell, it's time to have it checked by a professional, not by you.
What to Do If You Smell Burning From Your Furnace
The first step is to focus on the smell itself. A short dusty smell at the first furnace start of the season is not the same as an electrical, gas, rubber or smoky smell.
Use this basic approach:
- Dusty smell during first startup: Test it when the furnace is in operation. It should fade rather than get stronger.
- Electrical or burning-plastic smell: Shut down the furnace and have it checked before operating again.
- Gas or rotten-egg smell: Evacuate the premises and then call your gas company or emergency service from a safe distance. Avoid self troubleshooting of the furnace.
- Rubber, smoky, or unexplained recurring smell: Turn off the furnace and get it inspected.
- Carbon monoxide alarm: Evacuate the home and follow the directions of the carbon monoxide alarm manufacturer and local emergency responders. CO is colorless and odorless, so you cannot smell it.
When to Call a Professional Immediately
If the odor has an electrical, smoky, rubbery, or strange or recurring odor, discontinue use of the furnace until the source of the odor is determined. A technician can test electrical parts, blower, burners, heat exchanger and venting to pinpoint a cause.
If your furnace requires diagnosis or repair, visit our Residential Furnace Repair service page to learn more about professional furnace repair and service.
Don't schedule a furnace repair appointment when you suspect a gas leak. Evacuate first and then call your local gas utility or emergency service from a safe place.
Combustion equipment that is leaking or improperly maintained may be sources of CO, and EPA recommends professional inspection and maintenance of fuel-burning appliances.
FAQs
How long should the burning smell last the first time I turn on my furnace each year?
A mild dusty or burning-dust odor during the first startup of the heating season is usually temporary. It should fade as the furnace runs. Turn the furnace off if the smell persists or returns. Also shut it off if you notice smoke, unusual noises, or other problems. Have the furnace inspected before using it again.
What does an electrical burning smell from a furnace mean?
An electrical burning smell can indicate an overheating motor, blower problem, damaged wiring insulation, or another electrical component that is getting too hot. Turn the furnace off and, if you can safely do so, switch off its breaker. Don't restart the system until a qualified technician has identified and corrected the problem.
Should I turn off my furnace immediately if it smells like burning?
You should turn off your furnace immediately if the odor smells like electrical wires, burning plastic, rubber, smoke, or natural gas. The only time it is safe to keep running the furnace is during the first seasonal startup if the scent is purely a mild, dry dust odor that fades quickly.
What does it mean if my furnace smells like gas instead of burning dust?
If there is a natural gas leak in the fuel lines, gas valve or burner assembly, this could be detected by a sulfur or rotten egg smell. A gas odor is a serious safety threat and should not be confused with a dusty burning odor. Evacuate your home right away, and contact your gas provider or the emergency services.
