If your furnace smells while heating, it’s attempting to tell you something’s up. We’ve put together a list of the top six furnace smells so you can learn what causes them and how to fix them. These include:

  1. Burning smell from furnace
  2. Furnace smells like burning plastic
  3. Gas smell from furnace
  4. Furnace smells like sewer
  5. Furnace smells musty

1. The Furnace Smells Like It’s Burning

Cause: Dusty Furnace

If your furnace smells like burning, it’s probably occurring when you turn on your furnace for the first time in the fall. Like anything else in your home, your furnace gets dusty over time. This dust burns off when you turn on the heat, causing the burning dust smell from your furnace.

2. Furnace Smells Like Burnt Rubber or Plastic

Cause: Electrical Problem

If your furnace smells like burning plastic or burning rubber, it might have an electrical issue. This smell of burning can be created by melting plastic wire casing, which is a safety hazard. If you’re experiencing a melted plastic smell, turn off your heating system right away and call us at 435-753-5515 for furnace repair.

Cause: Overheated Motor or Cracked Furnace Exchanger

An electrical burning smell could also mean your furnace motor is too hot or the heat exchanger is cracked. The heat exchanger safely gets rid of carbon monoxide that’s naturally created during the combustion process.

If it cracks, carbon monoxide can seep into your house. This colorless gas is fatal in heavy concentrations. So, it’s important to have an HVAC professional do annual furnace maintenance and have functional carbon monoxide detectors.

Other symptoms of a cracked heat exchanger include:

  • Soot on or inside the furnace
  • Yellow burner flame, instead of blue
  • Chemical smell from furnace, like formaldehyde
  • Water around your furnace, as long as the condensate drain isn’t blocked
  • Flu-like symptoms

3. A Gas Smell Is Coming From the Furnace

It’s normal for your heating system to give off a small amount of gas when it starts up, so you might get a gas smell from your furnace. But it’s not normal to be smelling natural gas or rotten eggs throughout your home on a daily basis.

Cause: Gas Leak

If your furnace smells like gas continuously, turn it off. If you know where your main gas supply valve is, shut that off too. Then contact the gas company and us for assistance.

4. The Furnace Smells Like Sewage

If your furnace smells like sewer, or rotten eggs, you’ll want to ensure you don’t have a gas leak. If you don’t, the problem could be with your sewer lines and not your furnace. This is especially true if it’s been extremely dry lately.

Cause: Dry Sewer Trap or Sewer Leak

If you suspect your sewer trap is dry, you can try putting some water down the floor drain in your basement. If that doesn’t fix the issue, you might have a sewer leak, so you’ll want to call a company that does sewer line repair.

5. The Furnace Has a Musty Smell

If your furnace smells musty, mold and mildew have probably been growing in it for a while.

Cause: Dirty Ductwork

Your furnace uses air ducts to distribute warm air across your house. Mold can grow in the ductwork over time, especially if you live in a humid climate. You can eliminate the mold by having an HVAC technician do air duct cleaning.

You Can Count on Us for Your Furnace Repair Needs

Troubleshooting your heating and cooling system by yourself is hard. Your comfort is our top goal at Western Mechanical, Inc., so our pros are here to help you when you need us. When you need furnace repair in Cache Valley that you can trust, contact us at 435-753-5515.