Why Your Furnace Has a Strange Smell

As the weather turns cold and you transition from cooling to heating your home, you may be worried about strange furnace smells in the air. Learn about what the most common furnace smells mean and how concerned you should be about them.

The Furnace Smells Musty

Musty furnace smells almost always imply mold growth someplace in the HVAC system. To avoid exposing your family to allergy-inducing mold, address this problem right away.

A clogged air filter can lead to mold, so getting rid of the smell could be as easy as swapping out filter. If that fails to remove the smell, the AC evaporator coil placed near the furnace might be the root of the problem. This component gathers condensation, which will sometimes induce mold growth. You'll want a professional’s help to inspect and clean the evaporator coil. When this still doesn't help, start thinking about requesting air duct cleaning. This service eliminates hidden mold, regardless of where it's hiding in your ventilation.

The Furnace Smells Like Spoiled Eggs

This is one of the most worrisome furnace smells since it frequently implies a gas leak. The utility company puts in a particular substance known as mercaptan to the natural gas supply to make leaks easier to notice.

If you recognize a rotten egg smell near your furnace or originating from your ductwork, shut off the heater straightaway. If you know where the main gas supply valve is, shut that off too. Then, evacuate your home and dial 911, as well as your gas company. Don’t enter the house until a professional can verify 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 could mean the heat exchanger has cracked. This essential component safely contains combustion fumes, including carbon monoxide, so cracks could allow unsafe levels of CO gas into your home.

Carbon monoxide poisoning could be deadly, so turn off your furnace right away if you notice a sour odor. Then, reach out to an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is the culprit. For your health and safety going forward, make sure you have functional CO detectors on each floor of your home.

The Furnace Smells Dusty

When you start the furnace for the first time each fall, you should expect a dusty odor to fill the house for a few minutes. This is the smell of six months’ worth of dust burning away as the furnace wakes from its summer slumber. As long as the smell goes away within 24 hours, you shouldn't have anything to worry about.

The Furnace Has a Smoky Smell

Natural gas, oil and propane furnaces are combustion appliances, so they vent fumes safely out of your home. A smoky smell will sometimes mean the flue is backed up, and now fumes are backdrafting into your home. The odor might eventually reach the entire house, endangering your family’s health if you ignore it. So shut down the furnace and contact a professional straightaway to schedule a repair.

The Furnace Smells Like Burning Plastic

Overheating and melted electrical components are the most plausible reason for a burning plastic smell to appear. A malfunctioning fan motor is another possibility. If you don’t tackle the problem, an electrical fire might start, or your furnace could experience irreparable damage. Turn off the heating system immediately and call an HVAC technician for help troubleshooting and repairing this unusual furnace smell.

The Furnace Has an Oily Smell

If you have an oil furnace, you could detect this odor if the oil filter becomes blocked up. Try replacing it to determine if that fixes the problem. If the smell lingers for more than a day after carrying out this step, it might imply an oil leak. You’ll need help from an HVAC expert to address this problem.

The Furnace Smells Like Sewer Odors

Sewer gas smells pretty similar to rotten eggs, so first determine the possibility of a natural gas leak. If that’s not the source, the sewer lines may have an issue, like a dry trap or sewer leak. Try pouring water down the drains, including the basement floor drain, to fill dried-up sewer traps. If the smell sticks around, go ahead and contact a sewer line repair company.

Contact Becht/Givens Service Experts for Furnace Repair

When in doubt, call an HVAC technician to check and repair your furnace. At Becht/Givens Service Experts, we perform thorough diagnostic services to identify the problem before repairs begin. Then, we encourage the most viable, cost-effective repairs, alongside an up-front estimate for every option. Our ACE-certified technicians can resolve just about any heating malfunction, 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 Becht/Givens Service Experts office today.

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