Why Your Furnace Has a Strange Smell

As the weather turns cold and you swap from cooling to heating your home, you might be worried about unusual furnace smells in the air. Learn what the most common furnace smells mean and how proactive you should be about each one.

The Furnace Smells Musty

Musty furnace smells usually suggest mold growth someplace in the HVAC system. To avoid subjecting your family to these microorganisms, handle this problem right away.

A wet air filter can lead to mold, so getting rid of the smell can be as easy as replacing the filter. If that doesn’t work, the AC evaporator coil fastened near the furnace could be to blame. This component accumulates condensation, which will sometimes induce mold growth. You'll want a professional’s help to check and clean the evaporator coil. When all else fails, consider requesting air duct cleaning. This service cleans away hidden mold, regardless of where it’s growing in your ventilation.

The Furnace Smells Like Spoiled Eggs

This is one of the most nerve-wracking furnace smells since it probably suggests a gas leak. The utility company includes a special substance called mercaptan to the natural gas supply to make leaks easier to detect.

If you detect a rotten egg smell close to your furnace or originating from your vents, shut off the heater immediately. If you know where the main gas supply valve is located, shut that off too. Then, get out of the house and contact 911, in addition to your gas company. Don’t go back in 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 standing close to the furnace, this could mean the heat exchanger is cracked. This vital component contains combustion fumes, like carbon monoxide, so a crack could allow unsafe levels of CO gas into your home.

Carbon monoxide poisoning has the potential to be fatal, so switch off your furnace as soon as possible if you recognize 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 continued safety going forward, make sure you have reliable CO detectors on every floor of your home.

The Furnace Smells Dusty

When you fire up the furnace for the first time each fall, 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 from its summer slumber. As long as the smell disperses within a day, you don'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 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 may permeate the entire house, jeopardizing your family’s health if you let it continue. So turn off the furnace and call a professional straightaway to schedule a repair.

The Furnace Smells Like It's Burning Plastic

Overheating and melted electrical components are the most common reason for a burning plastic smell to make an appearance. A malfunctioning fan motor is also possible. If you don’t address the problem, an electrical fire could start, or your furnace could suffer from irreparable damage. Turn off the heating system right away and call an HVAC technician for help troubleshooting and repairing this weird furnace smell.

The Furnace Has an Oily Smell

If you use an oil furnace, you might notice this smell if the oil filter becomes blocked up. Try replacing it to find out if that fixes the problem. If the smell persists for more than one day after carrying out this step, it may suggest an oil leak. You’ll need help from an HVAC professional to address this problem.

The Furnace Reeks of Sewer Odors

Sewer gas smells very similar to rotten eggs, so first eliminate the likelihood of a natural gas leak. If that’s not the issue, your sewer lines may have an issue, for example a dry trap or sewer leak. Pour water down the drains, including the basement floor drain, to replenish dried-out sewer traps. If the smell lingers, you should contact a sewer line repair company.

Contact Teays Valley Service Experts for Furnace Repair

If you're still uncertain, call an HVAC technician to assess and repair your furnace. At Teays Valley Service Experts, we deliver thorough diagnostic services to pinpoint the problem before repairs begin. Then, we recommend the most viable, cost-effective repairs, alongside an up-front estimate for each option. Our ACE-certified technicians can handle just about any heating problem, 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 Teays Valley Service Experts office today.

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