If your furnace smells while heating, it’s trying 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 likely happening when you turn on your furnace for the first time in the fall. Like anything else in your home, your furnace accumulates dust over time. This dust burns up when you turn on the heat, resulting in 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 problem. 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 662-281-1231 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 gets rid of carbon monoxide that’s naturally created during the combustion process.

If it cracks, carbon monoxide can seep into your home. This colorless gas is fatal in large doses. So, it’s important to have an HVAC professional do annual furnace maintenance and have working 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, such as formaldehyde
  • Water around your furnace, as long as the condensate drain isn’t blocked
  • Flu-like symptoms

3. Gas Smell from Furnace

It’s normal for your heating system to let off a small amount 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 daily basis.

Cause: Gas Leak

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

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 issue could be with your sewer lines and not your furnace. This is especially true if it’s been very dry lately.

Cause: Dry Sewer Trap or Sewer Leak

If you suspect your sewer trap is dry, you can try pouring some water down the floor drain in your basement. If that doesn’t solve the problem, you might have a sewer leak, so you’ll want to contact a company that handles sewer line repair.

5. The Furnace Smells Like Mold

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

Cause: Dirty Ductwork

Your furnace uses air ducts to send warm air throughout your home. Mold can grow in the ductwork over time, especially if you live in a humid climate. You can get rid of 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 difficult. Your comfort is our top goal at Franklin's Heating & Air Conditioning, Inc, so our pros are here to help you when you need us. When you need furnace repair in Oxford that you can depend on, call us at 662-281-1231.