Why Your Furnace Has a Strange Smell

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

The Furnace Smells Musty 

Musty furnace smells generally indicate mold growth someplace in the HVAC system. To avoid exposing your family to these microorganisms, address this problem as quickly as possible. 

A wet air filter can lead to mold, so getting rid of the smell might be as easy as swapping out filter. If that fails to remove the smell, the AC evaporator coil placed near the furnace may be the root of the problem. This component collects condensation, which could trigger mold growth. You’ll need a professional’s help to examine and clean the evaporator coil. When all else fails, take a look at scheduling air duct cleaning. This service eliminates hidden mold, no matter where it’s hiding in your ventilation. 

The Furnace Smells Like Rotten Eggs 

This is one of the most nerve-wracking furnace smells since it most likely implies a gas leak. The utility company includes a useful substance called 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 vents, shut off the heater straightaway. If you remember where the main gas supply valve is located, 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 detect a sour smell that stings your nose while close to64} the furnace, this may mean the heat exchanger cracked open. This essential component contains68} combustion fumes, such as carbon monoxide, so cracks could pump unsafe levels of CO gas into your home. 

Carbon monoxide poisoning has the potential to be deadly, so shut off your furnace immediately 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 family’s safety going forward, ensure you have functional 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 can expect a dusty odor to appear for a few minutes. This is the smell of six months’ worth of dust burning up as the furnace wakes up. As long as the smell disperses 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 flowing back into your home. The odor can reach through the entire house, jeopardizing your family’s health if you let it continue. So turn 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 plausible reason for a burning plastic smell to make an appearance. A failing fan motor is another possibility. If you don’t address the problem, an electrical fire might start, or your furnace could end up with irreparable damage. Disable the heating system as soon as possible and contact an HVAC technician for help identifying and repairing this unusual furnace smell. 

The Furnace Has an Oily Smell 

If you use an oil furnace, you may notice this stench when the oil filter becomes clogged. Try replacing it to see if that fixes the problem. If the smell persists for more than one day after taking care of this step, it could suggest an oil leak. You should get help from an HVAC professional to address this problem. 

The Furnace Smells Like Sewer Odors 

Sewer gas smells pretty similar to rotting eggs, so first eliminate the potential for a natural gas leak. If that’s not the problem, your sewer lines may have an issue, like a dry trap or sewer leak. Pour water down all your drains, including the basement floor drain, to fill dried-up sewer traps. If the smell lingers, go ahead and contact a sewer line repair company. 

Contact Sunbeam Service Experts for Furnace Repair 

If you’re still uncertain, contact an HVAC technician to check and repair your furnace. At Sunbeam Service Experts, we offer comprehensive diagnostic services to determine the problem before we figure out the best solution. Then, we recommend the most viable, cost-effective repairs, alongside an up-front estimate for all options. Our ACE-certified technicians can manage just about any heating malfunction, and we back our work with a 100% satisfaction guarantee for one year. For details about why your furnace smells bad or to request furnace repair near you, please contact your local Sunbeam Service Experts office today. 

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