Why Does My Furnace Smell Like Burning?

If you notice a burning smell from your furnace, don’t panic. Read on to find out what the furnace burning smell means, and what to do about it. In addition, learn what other furnace smells mean and what you should do.

The cause: If you notice a burnt smell from the furnace when it kicks in for the first time in the fall, don’t panic. Dust accumulates on the furnace and in the ductwork. When the furnace heats up, it burns off the dust. 

The solution:  Wait it out. The smell should dissipate relatively quickly. You should also check your HVAC air filter - it’s a good idea to start the heating season with a clean filter.

The cause: If you notice the smell of burning plastic when your furnace is running, you may have an electrical problem. The melting plastic smell may be coming from the casing on the electrical wires in your furnace. That’s a big safety hazard. 

The solution: Turn off your furnace and call for HVAC repair. 

The cause: If you notice a gas smell from your gas furnace or the smell of rotten eggs, you may have a furnace gas leak. 

The solution: 

WHAT TO DO IF YOU SMELL GAS

• Do not try to light any appliance (furnace or gas stove)
• Do not touch any electrical switch or garage door opener.
• Do not use any phone in your home.
• Leave your house with your family and pets.
• Once outside, move away from the home and call your gas company.
• Follow the gas supplier’s instructions. 
• If you cannot reach your gas supplier, call the fire department.

The gas company or the fire department will arrive on the scene and determine the source of the leak. If you have a gas furnace, gas stove, gas water heater, or gas fireplace, any of them could be the source. They will shut off the gas, air out the house, and report to you what the issue is. They will tell you when it is safe to re-enter your home. 

You will be responsible for repairs to any gas line or valve inside your home. Call the appropriate contractor - an HVAC professional or a plumber can handle gas line repairs.

The cause: If the air coming out of the registers smells musty, you may have mold and mildew in your ductwork or air filter. This can be a hazard, especially in humid climates. 

The solution: Contact your HVAC company to assess the issue. They may offer comprehensive air duct cleaning that addresses the ductwork, cleans the HVAC components, and more. If they don’t offer the service, they may be able to recommend a reputable company. Keep in mind that the problem will recur until you take care of the excess humidity that caused the problem in the first place. 

The cause: Much like new carpeting, new furniture, or even a new car has a unique smell, so does a new furnace. Special coatings and lubricants account for this. The first time the new furnace kicks in, you may notice the smell of burning dust, burning plastic, or burning oil.  

The solution: Wait it out. Any odors should dissipate in about an hour. If odors are persistent or you see smoke, call your HVAC installer immediately.

You can prevent furnace smells and keep your furnace running safely and efficiently by taking care of it. This means changing your HVAC air filters regularly - usually every 30 to 90 days depending on the filter. Consider a filter subscription where you get them delivered to your home and have a new one when you need it.

Opt into Trane Diagnostics for peace of mind. You can give your dealer remote monitoring capabilities through the Trane Home App. Your Trane smart thermostat sends data about your HVAC system in real-time to your dealer, alerting them to maintenance needs and malfunctions, sometimes before you even realize there’s a problem. 

They can run furnace troubleshooting tests to pinpoint the issue. In some cases, they can solve the problem remotely. In this situation, you would grant them one-time dealer remote access (DRA). 

If they need to schedule an on-site service call, the HVAC technician will arrive with the knowledge gained from remote access. This enables shorter service calls and ensures the technician has the proper replacement parts.

Anne Fonda, Content Writer at Trane Technologies

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by John Kim, Senior Product Manager, Furnaces

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