Why Your Furnace Has a Strange Smell

As the weather gets colder and you transition from cooling to heating your home, you might be worried about strange furnace smells filling 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 imply mold growth hiding in the HVAC system. To avoid subjecting your family to mold and mildew spores, tackle this problem right away. 

A wet air filter can harbor mold, so getting rid of the smell might be as simple as swapping out filter. If that fails to remove the smell, the AC evaporator coil mounted near the furnace might be the root of the problem. This component gathers condensation, which could stimulate mold growth. You’ll want a professional’s help to inspect and clean the evaporator coil. When all else fails, start thinking about requesting air duct cleaning. This service eliminates hidden mold, regardless of where it’s growing in your ventilation. 

The Furnace Smells Like Rotting Eggs 

This is one of the most nerve-wracking furnace smells because it most likely implies a gas leak. The utility company includes a useful substance called mercaptan to the natural gas supply to make leaks more easily detected. 

If you recognize a rotten egg smell close to your furnace or originating from your ductwork, shut down the heater immediately. If you can find where the main gas supply valve is, shut that off as well. Then, leave the house and contact 911, followed by your gas company. Don’t enter the house until a professional tells you it’s safe. 

The Furnace Has a Sour Stench 

If you detect a sour smell that stings your nose while standing near64} the furnace, this might mean the heat exchanger has cracked. This important component contains68} combustion fumes, including carbon monoxide, so a crack may allow unsafe levels of CO gas into your home. 

Carbon monoxide poisoning can be fatal, so turn off your furnace immediately if you recognize a sour odor. Then, contact an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is the culprit. For your health and 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 should expect a dusty odor to show up for a few minutes. 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 goes away within a 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 to the exterior. A smoky smell can mean the flue is clogged, and now fumes are backdrafting into your home. The odor might eventually reach the entire house, jeopardizing your family’s health if you let it continue. So switch off the furnace and contact a professional as soon as you can to request furnace repair. 

The Furnace Smells Like It’s Burning Plastic 

Overheating and melted electrical components are the most plausible reason for a burning plastic smell to appear. A malfunctioning fan motor is also possible. If you don’t address the problem, an electrical fire could start, or your furnace could end up with irreparable damage. Shut off the heating system immediately and call an HVAC technician for help identifying and repairing this unusual furnace smell. 

The Furnace Has an Oily Smell 

If you own an oil furnace, you might pick up on this smell if the oil filter becomes clogged. Try replacing it to find out if that fixes the problem. If the smell remains for more than 24 hours after completing this step, it might imply an oil leak. You’ll be better off with help from an HVAC specialist to address this problem. 

The Furnace Smell Resembles Sewer Odors 

Sewer gas smells pretty similar to rotten eggs, so first determine the likelihood of a natural gas leak. If that’s not the source, the sewer lines could have an issue, like a dry trap or sewer leak. Pour water down the drains, including the basement floor drain, to refresh dried-up 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 check and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we deliver complete diagnostic services to determine the problem before we figure out the best solution. Then, we encourage the most viable, cost-effective repairs, along with an up-front estimate for every option. Our ACE-certified technicians can resolve 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 Service Experts Heating, Air Conditioning & Plumbing office today. 

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