Five Reasons Your Furnace Smells

If your furnace smells while running, it’s trying to tell you something’s up. We’ve compiled 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. Your Furnace Smells Like Burning Dust

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 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 caused 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 (503) 739-5400 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 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, like formaldehyde
• Water around your furnace, as long as the condensate drain isn’t blocked
• Flu-like symptoms

3. The Furnace Smells Like Gas or Rotten Eggs

It’s normal for your heating system to let off a little bit of gas when it starts up, 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, 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. 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 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 suspect 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. The Furnace Has a Musty Smell

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 over time, particularly if you live in a humid climate. You can get rid of the mold by having an HVAC technician do air duct cleaning.

Trust Us with Your Furnace Repair Needs

Troubleshooting your heating and cooling system on your own is difficult. Your comfort is our top priority at Three Rivers Heating and Cooling, so our pros are here to help you when you need us. When you need furnace repair in Portland that you can trust, call us at (503) 739-5400.