Why Your Furnace Has a Strange Smell

As the weather turns cold and you switch from cooling to heating your home, you might be worried about unusual furnace smells floating in the air. Find out what the most common furnace smells mean and how worried you should be about them.

The Furnace Smells Musty

Musty furnace odors generally suggest mold growth hiding in the HVAC system. To avoid exposing your family to mold and mildew spores, address this problem as soon as possible.

A wet air filter can lead to mold, so getting rid of the smell might be as easy as getting a new filter. If that doesn’t work, the AC evaporator coil fastened near the furnace may be the root of the problem. This component accumulates condensation, which will sometimes induce mold growth. You'll be better off with a professional’s help to check and clean the evaporator coil. When the problem still won't go away, consider scheduling air duct cleaning. This service cleans away hidden mold, no matter where it’s growing in your air ducts.

The Furnace Smells Like Spoiled Eggs

This is one of the most nerve-wracking furnace smells since it most likely suggests a gas leak. The utility company puts in a special substance known as mercaptan to the natural gas supply to make leaks easier to detect.

If you recognize a rotten egg smell near your furnace or originating from your air ducts, shut down the heater straightaway. If you remember where the main gas supply valve is, shut that off as well. Then, leave the house and contact 911, as well as your gas company. Don’t reenter the house until a professional confirms it’s safe.

The Furnace Has a Sour Stench

If you notice a sour smell that stings your nose while close to the furnace, this might mean the heat exchanger has cracked. This essential component contains combustion fumes, like carbon monoxide, so cracks might spew unsafe levels of CO gas into your home.

Carbon monoxide poisoning can be fatal, so turn off your furnace as soon as possible if you recognize a sour odor. Then, call an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is responsible. For your family's safety going forward, ensure you have reliable CO detectors on every floor of your home.

The Furnace Smells Dusty

When you turn on the furnace for the first time after a while, you probably expect a dusty odor to show up for a little while. This is the smell of six months’ worth of dust burning away as the furnace wakes up. As long as the smell dissipates within one day, you have nothing to worry about.

The Furnace Has a Smoky Smell

Natural gas, oil and propane furnaces are combustion appliances, so they vent fumes up and out of your home. A smoky smell can mean the flue is blocked, and now fumes are backdrafting into your home. The odor can reach through the entire house, endangering your family’s health if you neglect it. So switch off the furnace and call a professional as soon as you can to request furnace repair.

The Furnace Smells Like It's Burning Plastic

Overheating and melting electrical components are the most likely reason for a burning plastic smell to make an appearance. A failing fan motor is also possible. If you don’t address the problem, an electrical fire may start, or your furnace could suffer from irreparable damage. Shut off the heating system as soon as possible and contact an HVAC technician for help diagnosing and repairing this weird furnace smell.

The Furnace Has an Oily Smell

If you use an oil furnace, you may detect this smell whenever the oil filter becomes blocked up. Try replacing it to find out if that addresses the problem. If the smell persists for more than 24 hours after completing this step, it might suggest an oil leak. You'll be better off with help from an HVAC expert to fix this problem.

The Furnace Smell Resembles Sewer Odors

Sewer gas smells very similar to rotten eggs, so first determine the possibility of a natural gas leak. If that’s not the problem, the sewer lines might have an issue, such as a dry trap or sewer leak. Flush water down your own drains, including the basement floor drain, to replenish dry sewer traps. If the smell sticks around, you’ll need to contact a sewer line repair company.

Contact Service Experts Heating & Air Conditioning for Furnace Repair

If you're still uncertain, contact an HVAC technician to check and repair your furnace. At Service Experts Heating & Air Conditioning, we perform complete diagnostic services to pinpoint the problem before repairs begin. Then, we suggest the most viable, cost-effective repairs, alongside an up-front estimate for every option. Our ACE-certified technicians can handle just about any heating repair, and we back our work with a 100% satisfaction guarantee for one year. To learn more about why your furnace smells bad or to request furnace repair near you, please contact your local Service Experts Heating & Air Conditioning office today.

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