Why Your Furnace Has a Strange Smell

As the weather gets colder and you transition from cooling to heating your home, you may be worried about strange furnace smells in the air. Learn what the most common furnace smells mean and how worried you should be about them. 

The Furnace Smells Musty 

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

A wet air filter can harbor mold, so wiping out the smell could be as easy as replacing the filter. If that doesn’t help, the AC evaporator coil placed near the furnace might be to blame. This component accumulates condensation, which can stimulate mold growth. You’ll need a professional’s help to examine and clean the evaporator coil. When all else fails, start thinking about scheduling air duct cleaning. This service cleans away hidden mold, no matter where it’s hiding in your ventilation. 

The Furnace Smells Like Spoiled Eggs 

This is one of the most nerve-wracking furnace smells since it frequently suggests a gas leak. The utility company puts in a useful substance called mercaptan to the natural gas supply to make leaks more easily detected. 

If you recognize a rotten egg smell around your furnace or originating from your air ducts, shut down the heater straightaway. If you can find where the main gas supply valve is, shut that off as well. Then, evacuate your home and contact 911, in addition to your gas company. Don’t go back in the house until a professional tells you 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 could mean the heat exchanger has cracked. This vital component houses68} combustion fumes, including carbon monoxide, so a cracked heat exchanger may allow unsafe levels of CO gas into your home. 

Carbon monoxide poisoning could be deadly, so turn off your furnace right away if you recognize a sour odor. Then, contact an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is responsible. For your health and 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 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 up as the furnace wakes up. As long as the smell dissipates within 24 hours, 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 to the exterior. A smoky smell can mean the flue is clogged, and now fumes are settling back into your home. The odor might eventually reach the entire house, endangering your family’s health if you let it continue. So turn off the furnace and call a professional straightaway to request furnace repair. 

The Furnace Smells Like It’s Burning Plastic 

Overheating and melting electrical components are the most likely reason for a burning plastic smell to appear. A malfunctioning fan motor is another possibility. If you don’t tackle the problem, an electrical fire could start, or your furnace could suffer from irreparable damage. Disable the heating system immediately and call an HVAC technician for help troubleshooting and repairing this unpleasant furnace smell. 

The Furnace Has an Oily Smell 

If you own an oil furnace, you might detect this odor when the oil filter becomes clogged. Try replacing it to see if that fixes the problem. If the smell lingers for more than a day after completing this step, it might suggest an oil leak. You’ll be better off with help from an HVAC professional to address this problem. 

The Furnace Smells Like Sewer Odors 

Sewer gas smells quite similar to rotting eggs, so first rule out the potential for a natural gas leak. If that’s not the issue, your home’s sewer lines might have an issue, for example a dry trap or sewer leak. Try pouring water down all your drains, including the basement floor drain, to refresh dried-up sewer traps. If the smell sticks around, go ahead and contact a sewer line repair company. 

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

When in doubt, call an HVAC technician to check and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we perform complete diagnostic services to identify the problem before the work begins. Then, we suggest the most viable, cost-effective repairs, as well as an up-front estimate for all options. Our ACE-certified technicians can handle just about any heating repair, 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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