Why Your Furnace Has a Strange Smell

As the weather gets colder and you transition from cooling to heating your home, some homeowners are worried about weird furnace smells in the air. Learn about what the most common furnace smells mean and how concerned you should be about each one. 

The Furnace Smells Musty 

Musty furnace smells generally suggest mold growth hiding in the HVAC system. To avoid subjecting your family to allergy-inducing mold, tackle this problem right away. 

A clogged air filter can lead to mold, so wiping out the smell can be as simple as replacing the filter. If that doesn’t work, the AC evaporator coil placed near the furnace may be the root of the problem. This component accumulates condensation, which can trigger mold growth. You’ll want a professional’s help to check and clean the evaporator coil. When this still doesn’t help, consider scheduling air duct cleaning. This service cleans away hidden mold, no matter where it’s hiding in your ventilation. 

The Furnace Smells Like Rotting Eggs 

This is one of the most nerve-wracking furnace smells because it most likely indicates a gas leak. The utility company includes a special substance known as mercaptan to the natural gas supply to make leaks easier to detect. 

If you detect a rotten egg smell around your furnace or coming from your air ducts, 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, as well as your gas company. Don’t go back in 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 close to64} the furnace, this may mean the heat exchanger cracked open. This essential component contains68} combustion fumes, such as carbon monoxide, so a crack may allow unsafe levels of CO gas into your home. 

Carbon monoxide poisoning has the potential to be fatal, so turn off your furnace as soon as possible 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 to blame. For your continued safety going forward, see to it that you have reliable CO detectors on each floor of your home. 

The Furnace Smells Dusty 

When you turn on the furnace for the first time every fall, you should expect a dusty odor to show up for a brief moment. 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 disperses within one 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 clogged, and now fumes are flowing back into your home. The odor might eventually reach the entire house, endangering your family’s health if you let it continue. So switch off the furnace and contact a professional right away to arrange for repair. 

The Furnace Smells Like Burning Plastic 

Overheating and melted electrical components are the most common reason for a burning plastic smell to appear. 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 immediately and contact an HVAC technician for help identifying and repairing this unpleasant furnace smell. 

The Furnace Has an Oily Smell 

If you own an oil furnace, you could detect this stench when the oil filter becomes blocked up. Try replacing it to determine if that addresses the problem. If the smell remains for more than one day after taking care of this step, it may suggest an oil leak. You should get help from an HVAC professional to handle this problem. 

The Furnace Smells Like Sewer Odors 

Sewer gas smells very similar to rotting eggs, so first eliminate the potential for a natural gas leak. If that’s not the source, your sewer lines could have an issue, such as a dry trap or sewer leak. Try pouring water down the drains, including the basement floor drain, to refresh dried-out sewer traps. If the smell lingers, you’ll need to contact a sewer line repair company. 

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

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