Why Your Furnace Has a Strange Smell

As the weather turns cold and you swap from cooling to heating your home, some homeowners are worried about weird furnace smells floating in the air. Find out what the most common furnace smells could suggest and how worried you should be about each one. 

The Furnace Smells Musty 

Musty furnace odors usually indicate mold growth hiding in the HVAC system. To avoid exposing your family to allergy-inducing mold, tackle this problem as quickly as possible. 

A clogged air filter can lead to mold, so getting rid of the smell might be as simple as getting a new filter. If that fails to remove the smell, the AC evaporator coil placed near the furnace might be to blame. This component gathers condensation, which will sometimes trigger mold growth. You’ll be better off with a professional’s help to examine and clean the evaporator coil. When the problem still won’t go away, start thinking about requesting air duct cleaning. This service cleans away hidden mold, no matter where it’s growing in your air ducts. 

The Furnace Smells Like Rotting Eggs 

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

If you recognize a rotten egg smell near your furnace or originating from your ductwork, shut down the heater immediately. If you know where the main gas supply valve is, shut that off as well. Then, evacuate your home and dial 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 notice a sour smell that stings your nose while close to64} the furnace, this might mean the heat exchanger is cracked. This vital component houses68} combustion fumes, including carbon monoxide, so a cracked heat exchanger might spew unsafe levels of CO gas into your home. 

Carbon monoxide poisoning has the potential to be lethal, so turn off your furnace as soon as possible 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 family’s safety going forward, ensure 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 after a while, you can expect a dusty odor to fill the house 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 goes away within a day, 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 to the exterior. A smoky smell can mean the flue is blocked, and now fumes are backdrafting into your home. The odor can reach through the entire house, risking your family’s health if you ignore it. So shut down the furnace and call a professional straightaway to arrange for repair. 

The Furnace Smell Resembles Burning Plastic 

Overheating and melting electrical components are the most common reason for a burning plastic smell to make an appearance. A failing fan motor is also possible. If you don’t correct the problem, an electrical fire could start, or your furnace could experience irreparable damage. Disable the heating system as soon as possible and call an HVAC technician for help troubleshooting and repairing this unpleasant furnace smell. 

The Furnace Has an Oily Smell 

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

The Furnace Smell Resembles Sewer Odors 

Sewer gas smells very similar to rotting eggs, so first determine the potential for a natural gas leak. If that’s not the source, your home’s 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 fill dried-out sewer traps. If the smell lingers, go ahead and contact a sewer line repair company. 

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

If you’re still uncertain, call an HVAC technician to assess and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we offer comprehensive diagnostic services to pinpoint the problem before we figure out the best solution. Then, we suggest the most viable, cost-effective repairs, along with an up-front estimate for each option. Our ACE-certified technicians can manage 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 & Plumbing office today. 

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