Why Does My Heater Smell?

Weird smells are among the most common complaints people have about their heaters. But which smells are normal and which are a cause for alarm? As a savvy homeowner, it’s important to be aware of the warning signs of a heating issue and to know when it’s time to call for heating service.

Heater Smells Like Burning

If it’s the first time you’re turning on your furnace for the season, it’s normal for you to smell a weird odor as dust burns off the unit.

The smell should begin fading fairly quickly and usually disappears after the system has been running for a short time. As long as the odor is temporary and does not become stronger, it can generally be safely ignored.

Heater Smells Like Burning Plastic or Metal

If you smell something like overheated metal or burning plastic, you may have a bigger problem, like an overheating motor, damaged wiring or another electrical or mechanical problem. Immediately turn off your heater and call for service to avoid a potential fire hazard.

Heater Smells Like Rotten Eggs

If you have a gas furnace and notice a rotten egg or sulfur smell, you may have a natural gas leak. Natural gas is odorless, so in order to make it detectable, a chemical called mercaptan is added. This chemical is responsible for that unpleasant smell.

Since natural gas is highly flammable and can be ignited by even a small spark, it is imperative that you shut off your heater, get your family (and pets!) out of your home and immediately call your gas company.

What Should You Not Do If You Smell Gas Near Your Furnace?

Do NOT:



• Turn lights or electronics on or off
• Use a phone inside the house
• Smoke or light a match or lighter in or near your home
• Do anything else that could create a spark

Heater Smells Like Fish

Smell something fishy? Many people assume that they have a dead animal in their crawlspace, but it can also come from an overheated, burning electrical component in your heater. As this is a serious fire hazard, you should shut off your heater and call for heating service.

Heater Smells Smoky or Like Exhaust

A persistent smoky or exhaust-like smell from a gas furnace is not normal. It may indicate a combustion or venting problem that is allowing exhaust gases to enter the home instead of leaving through the vent system. Turn the furnace off and have it inspected before using it again.

Can a Furnace Problem Cause Carbon Monoxide Without a Smell?

Yes. Carbon monoxide is colorless and odorless, so you cannot rely on smell to warn you that it is present. Problems with combustion, venting or other fuel-burning furnace components can allow carbon monoxide to build up indoors.

If your home has any gas appliances, such as a gas water heater, dryer, oven, range or furnace, it is important to have operating carbon monoxide sensors inside your home. Like fire alarms, carbon monoxide alarms should be periodically tested to ensure they are working properly.

When Should You Turn Off Your Heater Because of a Smell?

The only furnace smell that doesn’t usually indicate a problem is the temporary burning-dust odor you might notice when your heater runs for the first time after sitting unused. Most other unusual smells coming from your vents or furnace are worth taking seriously.

If your furnace or heat pump produces an unusual odor or does not seem to be working as well as it did last fall or winter, call Tom’s Mechanical at (817) 277-4493. We are available 24/7 for Arlington residents experiencing HVAC emergencies.