man holding nose burning smell in house

A burning plastic smell in your house can be annoying, confusing, and even alarming. Determining what’s causing the smell is essential, but there’s no need to panic. A burning smell can be typical and non-threatening. At the same time, please don’t put it off. A burning smell might signal serious issues or fire hazards.

First and foremost, determine from where the odor is emanating. Next, take steps to resolve the issue or prevent a fire, such as shutting off or unplugging the source. Finally, call a trained professional, like an HVAC technician or electrician.

Sources of Burning Plastic Smell in House

The smell of burning plastic is unmistakable, but it can be challenging to locate the source. Electrical wiring, the HVAC system, and electric appliances are familiar sources of burning plastic odors.

Electrical Wiring

A burning plastic smell can come from electrical cords or wiring behind the walls. Electrical cables and wires are coated with plastic insulation that can melt when damaged. Cords sustain damage from people, animals, short circuits, power overloads, and loose connections. Outdated wiring in old houses and incorrect wiring in new homes are two additional causes of electrical problems, all of which can spark fires. You might notice other indications of electrical issues, such as humming or buzzing noises, flickering lights, and sparks.

To locate the source of the smell, turn off your electrical switches one at a time, going from room to room. If the smell goes away after flipping a switch, it indicates the location of the electrical issue. Once you determine the source, unplug it or leave the switch off, and call an electrician.

HVAC System

A burning plastic smell can originate in your furnace or air conditioner components and spread throughout the house via ductwork.

Clogged Filter

A clogged filter causes dust to accumulate in the furnace. The dust emits an odor when the furnace heats up and burns the dust. A dirty air filter also causes the blower motor to work harder to push air through the system. A burning smell could indicate that the furnace is overheating.

Blower Motor Issues

Motor bearings need to be lubricated regularly. The bearings can produce a burning smell from friction if not maintained.

Some blower motors use rubber belts. A worn belt and the furnace’s heat might create a burning plastic smell.

Blower motors should last ten years, but they might burn out sooner from overuse and strain. A burning smell could indicate the motor is burning out.

Foreign Object In System

A small toy, bottle cap, crayon, or other plastic objects might have fallen through a vent and into a duct. The smell arises when the heat comes on, and the thing heats up. Another possibility is a foreign object makes its way into the furnace and melts when the burners are firing.

Bad AC Capacitor/Faulty Wiring

A burning smell from the AC is another possibility. The outdoor air conditioning unit contains a capacitor, an electrical component that kick-starts the compressor motor. The capacitor releases a burning plastic smell if an overheating motor, power surge, or deterioration damages it.

Electric Appliances

Check if the smell is coming from the appliances in your house. Did someone leave on a curling iron? Is a small electrical device overheating from overuse or plugged in too long? Large appliances like refrigerators and water heaters can also overheat. When you locate the source, unplug the machine and inspect the wire, socket, and surrounding areas for damage. Call a professional to examine a large appliance or replace it.

Some appliance smells are expected, such as a burning plastic odor from an electric heater when it’s first turned on. New electric ovens also release a plastic smell when used the first few times. If the scent doesn’t diminish, however, seek professional advice.

Other Reasons Why Your Furnace Smells Like It’s Burning

Gas and oil furnaces use combustion to produce heat, but there likely is an issue if your furnace smells like burning.

man showing dust on furnace causing burning smell

Dust is burning on your furnace.

A furnace turned on for the first time of the season commonly produces a burning smell. Dust accumulates on the burners and heat exchangers when the furnace is unused and burns off when it’s turned on. Don’t be concerned if the smell goes away after a few minutes, but you might consider cleaning your ducts.

man changing furnace air filter

Your air filter is dirty.

A dirty air filter might cause a burning smell from dirt accumulations that burn off when the furnace turns on. A dirty air filter might cause a furnace to overheat and produce a burning smell. The furnace has to work harder to pull air through the system when the filter is clogged. Keep your furnace operating smoothly with regular maintenance, and be sure you know how often to change the air filter.

electrical burning in furnace

There is electrical burning.

The furnace should shut down automatically if it overheats or an electrical fire starts unless the safety feature malfunctions. Electrical fires sometimes smell fishy or resemble urine. If you detect a burning or fishy smell from the AC or furnace, shut it down and call an HVAC professional.

yellow flame indicating gas issue with furnace

There may be a problem with the gas flow.

Some gas flow issues can be detected by observing the check burner flames. Yellow or orange flames or flames that flicker indicate problems. Steady blue flames are normal. If nothing is amiss with the flames, but you smell gas, shut off the furnace and call an HVAC technician.

overheated circuit board in furnace

Smell of Gunpowder

An overheated furnace circuit board or fan motor might smell like gunpowder. Shut off the furnace and call an HVAC service.

person changing oil filter on furnace

Smell of Oil or Smoke

An oil or smoke smell from an oil furnace typically means the oil filter needs to be changed. Turn off the furnace and call an HVAC professional if the smell persists after changing the oil filter.

Frequently Asked Questions

Is it normal for a furnace to smell when first turned on?

It’s not unusual to smell a burning odor when the furnace is first turned on at the start of the season. Dust accumulates on the furnace’s components when unused for a long time. The dust burns off when the furnace is turned on and emits a burning odor.

Why does my new furnace smell like burning?

New furnaces have protective coatings on their components to prevent rust formation. The coating emits an odor as it burns off when the furnace is used for the first time. The smell should dissipate over time.

Can a furnace smell like gas?

It’s not usual to smell a faint odor from a gas furnace. The furnace’s gas valve releases a stream of gas that ignites when the furnace starts up.

On the other hand, a strong and constant gas odor indicates a gas leak. In that case, shut off the furnace and gas supply, and call an HVAC technician.

What does a furnace leak smell like?

Gas leaks smell like rotten eggs or sulfur. Natural gas has no odor but contains an odorous additive, so gas leaks can be detected. Turn off the main gas supply, vacate the premises, and call the gas company.

Why does my furnace smell like a dead animal?

A dead animal likely causes a dead animal smell from your furnace. A mouse or other rodent might have crawled into the furnace or ductwork, died, and decomposed. The carcass must be removed, and the duct cleaned thoroughly to eliminate the smell.

Furnaces and air conditioners release all types of smells when issues arise. Dirty sock syndrome is a typical HVAC system issue.


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