Why Your Furnace Has a Strange Smell

As the weather cools down and you swap from cooling to heating your home, you might be worried about weird furnace smells floating in the air. Learn about what the most common furnace smells could suggest and how worried you should be about each one.

The Furnace Smells Musty

Musty furnace smells generally imply mold growth somewhere in the HVAC system. To avoid exposing your family to mold and mildew spores, address this problem as quickly as possible.

A clogged air filter can lead to mold, so eliminating the smell could be as easy as swapping out filter. If that doesn’t work, the AC evaporator coil mounted near the furnace could be the root of the problem. This component accumulates condensation, which can stimulate mold growth. You’ll need a professional’s help to inspect and clean the evaporator coil. When all else fails, take a look at requesting air duct cleaning. This service cleans away hidden mold, no matter where it’s growing in your ventilation.

The Furnace Smells Like Rotten Eggs

This is one of the most concerning furnace smells due to the fact that it most likely implies a gas leak. The utility company includes a particular substance called mercaptan to the natural gas supply to make leaks easier to notice.

If you detect a rotten egg smell near your furnace or out of your vents, switch off the heater immediately. If you remember where the main gas supply valve is located, shut that off as well. Then, evacuate your home and contact 911, followed by your gas company. Don’t reenter the house until a professional confirms it’s safe.

The Furnace Has a Sour Stench

If you detect a sour smell that stings your nose while close to the furnace, this might mean the heat exchanger is cracked. This important component safely contains combustion fumes, like carbon monoxide, so cracks could allow unsafe levels of CO gas into your home.

Carbon monoxide poisoning has the potential to be fatal, so switch off your furnace right away if you recognize a sour odor. Then, call an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is to blame. For your family's safety going forward, make sure you have working CO detectors on each floor of your home.

The Furnace Smells Dusty

When you start the furnace for the first time after a while, you should expect a dusty odor to fill the house for a little while. This is the smell of six months’ worth of dust burning off as the furnace wakes from its summer slumber. As long as the smell dissipates within 24 hours, 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 safely out of your home. A smoky smell can mean the flue is blocked, and now fumes are settling back into your home. The odor can reach through the entire house, jeopardizing your family’s health if you ignore it. So switch off the furnace and get in touch with a professional straightaway to request furnace repair.

The Furnace Smells Like Burning Plastic

Overheating and burned electrical components are the most common reason for a burning plastic smell to come from your furnace. A malfunctioning fan motor is another possibility. If you don’t correct the problem, an electrical fire might start, or your furnace could experience irreparable damage. Disable the heating system as soon as possible and contact an HVAC technician for help troubleshooting and repairing this unusual furnace smell.

The Furnace Has an Oily Smell

If you use an oil furnace, you might notice this stench if the oil filter becomes clogged. Try replacing it to find out if that resolves the problem. If the smell lingers for more than one day after taking care of this step, it might indicate an oil leak. You’ll need help from an HVAC professional to handle this problem.

The Furnace Smells Like Sewer Odors

Sewer gas smells very similar to spoiled eggs, so first determine the potential for 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. Flush water down the drains, including the basement floor drain, to replenish dried-up sewer traps. If the smell persists, go ahead and contact a sewer line repair company.

Contact Service Experts Heating & Air Conditioning for Furnace Repair

If you're still unsure, contact an HVAC technician to assess and repair your furnace. At Service Experts Heating & Air Conditioning, we perform comprehensive diagnostic services to determine the problem before we figure out the best solution. Then, we recommend the most viable, cost-effective repairs, as well as an up-front estimate for all options. Our ACE-certified technicians can resolve just about any heating problem, and we back our work with a 100% satisfaction guarantee for one year. To ask questions 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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