If your furnace smells while running, it’s trying to tell you something’s up. We’ve put together a list of the top six furnace smells so you can know what causes them and how to repair 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 happening when you turn on your furnace for the first time in the fall. Like anything else in your house, your furnace gets dusty over time. This dust burns off when you turn on the heat, resulting in the burning dust smell from your furnace.

2. Furnace Smells Like Burning 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 issue. If you’re experiencing a melted plastic smell, turn off your heating system right away and call us at 530-885-8081 for furnace repair.

Cause: Overheated Motor or Cracked Furnace Exchanger

An electrical burning smell could also mean your furnace motor is overheated or the heat exchanger is cracked. The heat exchanger safely exhausts carbon monoxide that’s naturally produced during the combustion process.

If it cracks, carbon monoxide can leak into your home. This invisible gas is fatal in heavy concentrations. So, it’s important to have an HVAC professional do routine furnace maintenance and have working carbon monoxide detectors.

Other signs 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 near your furnace, as long as the condensate drain isn’t plugged
  • Flu-like symptoms

3. A Gas Smell Is Coming From the Furnace

It’s normal for your heating system to let off a little bit of gas when it turns on, so you might notice a gas smell from your furnace. But it’s not normal to be smelling natural gas or rotten eggs throughout your home on a regular 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. Furnace Smells Like Sewer

If your furnace smells like sewer, or rotten eggs, you’ll want to ensure you aren’t dealing with a gas leak. If you don’t, the issue 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 think your sewer trap is dry, you can try pouring some water down the floor drain in your basement. If that doesn’t fix the problem, you might have a sewer leak, so you’ll want to contact a company that does sewer line repair.

5. Furnace Smells Musty

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

Cause: Dirty Ductwork

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

Depend on Us for Your Furnace Repair Needs

Troubleshooting your heating and cooling system by yourself is hard. Your comfort is our number one priority at Forster Heating, so our pros are here to help you when you need us. When you need furnace repair in Auburn that you can trust, contact us at 530-885-8081.