Five Common Furnace Smells Explained

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 likely happening when you turn on your furnace for the first time in the fall. Like anything else in your house, 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 Burning 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 caused by melting plastic wire casing, which is a safety issue. If you’re noticing a melted plastic smell, turn off your heating system right away and call us at 636-456-5041 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 produced during the combustion process.

If it cracks, carbon monoxide can leak into your home. This colorless gas is fatal in heavy concentrations. So, it’s important to have an HVAC professional do routine furnace maintenance and have functional 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 around 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 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 typical to be smelling natural gas or rotten eggs throughout your home on a daily basis.

Cause: Gas Leak

If your furnace smells like gas frequently, turn it off. If you know where your main gas supply valve is, turn that off too. Then call the gas company and us for help.

4. Furnace Smells Like Sewer

If your furnace smells like sewer, or rotten eggs, you’ll want to make sure you aren’t dealing with 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 very dry lately.

Cause: Dry Sewer Trap or Sewer Leak

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

5. Furnace Smells Musty

If your furnace smells musty, mold and mildew have probably 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 as time goes on, especially if you live in a humid climate. You can get rid of the mold by having an HVAC technician do air duct cleaning.

You Can Count on Us for Your Furnace Repair Needs

Trying to fix your heating and cooling system by yourself is hard. Your comfort is our number one goal at Schraer Heating & Air Conditioning, so our pros are here to help you when you need us. When you need furnace repair in Warrenton that you can depend on, call us at 636-456-5041.