What‘s That Weird Odor When You Turn on the Heat?

It isn’t always normal for your home to smell strange when you turn on the heat. Some smells are harmless and expected, while others warrant a call to a HVAC company. How do you determine when to call a specialist? Check out these tips from our experts to learn more.

Strange Furnace Smells and What They Might Mean

Scent: Burned Dust

A burnt or dusty smell when you turn on your heating system for the first time in the winter or fall is normal. The cause is likely dust and dirt particles that settled on the components in your heating equipment during the spring and summer. 

If the smell persists for more than a few days, try changing the air filter. If the smell continues after a couple of heating cycles, call a HVAC specialist for an inspection. The heating system or the ductwork might need to be cleaned.

Scent: Rotten Eggs

If natural gas powers your heating equipment and you smell rotten eggs or sulfur, there may be a gas leak in your home.

• If you see sparks or flames, evacuate your house and call 911.
• If this is not the case, make sure all the burners on your gas stove are turned off.
• Open all doors and windows.
• If your grass or shrubs have look brown or rusty, this may be gas pouring out of the pipes. If this is the case, call 911 immediately and then the gas company.

As you leave your home, do not:

• Turn any lights on or off
• Use any phones; wait until you get to a neighbor’s house
• Use a garage door opener to open the garage
• Drive your car to a neighbor’s home
• Unplug electrical devices

Smell: Mildew or Dirty Socks

When you turn the heat on and your home smells like musty books or a gym bag, bacteria or mold might be present on the heating system’s coils.

This problem tends to happen most often with heat pumps rather than furnaces because furnaces reach temperatures high enough to kill bacteria and mold. Heat pumps transfer heat from outdoor air, so their coils don’t reach these high temperatures.

If you have a heat pump, schedule an inspection. The coils might need to be cleaned.

If you have a furnace and notice a moldy or locker room-like smell, call a HVAC company. The ductwork might have mold and need to be cleaned.

Smell: Burning Rubber or Plastic

When you smell burning plastic or rubber, inspect the air vents in your home for obstructions. A rubber or plastic item might be on top of or inside a register. If there is, remove it.

If you can’t find any obstructions or the smell persists, shut off the heating system, unplug it, and call a professional to schedule an inspection and repair.

Smell: Electrical, Metallic or Overheating

When the heating equipment produces a smell that reminds you of burning oil or metal, it might be overheating because of a failing motor or frayed wires.

If the smell does not go away after one or two heating cycles, immediately it turn off and unplug the heating equipment. Allowing it to continue running could cause a fire or lead to a higher repair bill. Then call a HVAC company.

The best way to avoid heating system odors is with annual maintenance. During a maintenance visit, a HVAC specialist will inspect your heating system for failing components, dirty parts, frayed wires and other issues that could cause strange smells or mechanical problems. If you notice a bad smell coming from your heating system, call AAA Heating and Cooling right away so it doesn’t fail when you need it most.