What Causes the Burning Smell When I Turn On My Furnace?

When you turn on your furnace at the first chill in the air, don’t be alarmed if your furnace emits an unusual burning odor. It’s possible that this is typical. Here are several causes of the burning smell from your furnace and what you should do about them, if anything.

Blocked Air Filter

Dust, pet hair, and other material collect in an air filter, resulting in clogging. As the heated air passes through the filter, it can cause an unpleasant burning smell. Replacing the old filter with a new one eliminates the odor. A persistent burning smell may require an inspection and repair by a professional HVAC technician.


Your heating system may smell burning when you first turn it on. In the summer, dust can gather on burners, heat exchangers, and other heating parts. The heater should burn away dust, leaving behind an unpleasant smell. There is no reason to worry as long as the odor dissipates within minutes and shows no sign of a malfunctioning heater.

Wiring Issues

An electrical problem can cause the burning odor in certain instances. A wiring issue isn’t common, but it can happen, so it’s essential to identify the culprit. Consult a professional HVAC professional if the smell persists, especially if burning plastic is mixed with it.

Although the first dusty/burnt stench may seem quite normal, you should be careful of the following odd smells:

Musty and Moldy Smell

You might have a dirty air filter or mold or bacteria accumulating in your HVAC system. Check the filter and replace it if necessary. Organic growth on your cooling coil or in your ductwork could also be a cuplrit. An HVAC contractor or duct cleaning specialist will need to clean your HVAC system.

Rotten Eggs or Sulfuric Odors

Using gas appliances can cause your house to smell like rotten eggs or sulfur. Leave the house immediately and call the gas company since gas leaks can cause fires or explosions. Gas leaks should always be handled by skilled professionals.

Always Maintain Your Furnace

Seeing a burning smell as your heater turns on isn’t necessarily a cause for concern. The odor is most likely caused by some minor maintenance on your heating system. Get into the habit of scheduling a fall furnace maintenance in advance of chilly weather to decrease the likelihood of a furnace malfunction.