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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 in the air. Learn what the most common furnace smells could mean and how worried you should be about each one. 

The Furnace Smells Musty 

Musty furnace smells generally suggest mold growth somewhere in the HVAC system. To avoid subjecting your family to allergy-inducing mold, handle this problem as quickly as possible. 

A wet air filter can harbor mold, so wiping out the smell can be as straightforward as replacing the filter. If that doesn’t help, the AC evaporator coil placed near the furnace could be the culprit. This component gathers condensation, which will sometimes induce mold growth. You’ll want a professional’s help to examine and clean the evaporator coil. When the problem still won’t go away, take a look at requesting air duct cleaning. This service cleans away hidden mold, no matter where it’s growing in your air ducts. 

The Furnace Smells Like Rotten Eggs 

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

If you detect a rotten egg smell near your furnace or out of your ductwork, switch off the heater immediately. If you know where the main gas supply valve is, shut that off also. Then, evacuate your home and contact 911, in addition to your gas company. Don’t reenter the house until a professional confirms it’s safe. 

The Furnace Has a Sour Stench 

If you discover a sour smell that stings your nose while standing near64} the furnace, this might mean the heat exchanger is cracked. This vital component houses68} combustion fumes, such as carbon monoxide, so cracks may spew unsafe levels of CO gas into your home. 

Carbon monoxide poisoning has the potential to be fatal, so turn off your furnace immediately 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, make sure you have functional CO detectors on each floor of your home. 

The Furnace Smells Dusty 

When you fire up the furnace for the first time every fall, you can expect a dusty odor to show up for a brief moment. This is the smell of six months’ worth of dust burning away as the furnace wakes up. As long as the smell disperses 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 will sometimes mean the flue is clogged, and now fumes are backdrafting into your home. The odor might eventually reach the entire house, risking your family’s health if you let it continue. So shut down the furnace and get in touch with a professional straightaway to schedule a repair. 

The Furnace Smell Resembles Burning Plastic 

Overheating and melted electrical components are the most plausible 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. 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 use an oil furnace, you might pick up on this stench if the oil filter becomes clogged. Try replacing it to determine if that resolves the problem. If the smell lingers for more than one day after carrying out this step, it may imply an oil leak. You’ll be better off with help from an HVAC professional to handle this problem. 

The Furnace Reeks of Sewer Odors 

Sewer gas smells quite similar to spoiled eggs, so first rule out the likelihood of a natural gas leak. If that’s not the source, the sewer lines may have an issue, such as a dry trap or sewer leak. Try pouring water down the drains, including the basement floor drain, to refresh dry sewer traps. If the smell sticks around, you’ll need to contact a sewer line repair company. 

Contact Service Experts Heating, Air Conditioning & Plumbing for Furnace Repair 

If you’re still unsure, call an HVAC technician to examine and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we perform complete diagnostic services to pinpoint the problem before we figure out the best solution. Then, we recommend the most viable, cost-effective repairs, alongside an up-front estimate for each option. Our ACE-certified technicians can resolve just about any heating repair, 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 Service Experts Heating, Air Conditioning & Plumbing office today. 

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