Why Your Furnace Has a Strange Smell

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

The Furnace Smells Musty 

Musty furnace odors generally indicate mold growth somewhere in the HVAC system. To avoid subjecting your family to allergy-inducing mold, tackle this problem as soon as possible. 

A wet air filter can harbor mold, so eliminating the smell can be as simple as replacing the filter. If that doesn’t work, the AC evaporator coil placed near the furnace could be to blame. This component gathers condensation, which could stimulate mold growth. You’ll need a professional’s help to check and clean the evaporator coil. When all else fails, consider scheduling air duct cleaning. This service eliminates hidden mold, no matter where it’s growing in your ductwork. 

The Furnace Smells Like Rotten Eggs 

This is one of the most worrisome furnace smells since it most likely indicates a gas leak. The utility company adds a useful 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 coming from your vents, switch off the heater immediately. If you know where the main gas supply valve is located, shut that off as well. Then, get out of the house and call 911, followed by your gas company. Don’t go back in the house until a professional can verify 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 could mean the heat exchanger cracked open. This vital component safely contains68} combustion fumes, including carbon monoxide, so a crack could pump unsafe levels of CO gas into your home. 

Carbon monoxide poisoning could be deadly, so shut off your furnace right away if you detect a sour odor. Then, call an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is to blame. For your family’s safety going forward, make sure you have working CO detectors on every floor of your home. 

The Furnace Smells Dusty 

When you turn on the furnace for the first time every fall, you can expect a dusty odor to appear 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 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 blocked, and now fumes are flowing back into your home. The odor may permeate the entire house, endangering your family’s health if you let it continue. So shut down the furnace and contact a professional right away to request furnace repair. 

The Furnace Smells Like Burning Plastic 

Overheating and melting electrical components are the most likely reason for a burning plastic smell to appear. 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. Shut off the heating system immediately and call an HVAC technician for help diagnosing and repairing this weird furnace smell. 

The Furnace Has an Oily Smell 

If you use an oil furnace, you might detect this odor when the oil filter becomes clogged. Try replacing it to determine if that fixes the problem. If the smell lingers for more than a day after completing this step, it could indicate an oil leak. You’ll need help from an HVAC expert to fix this problem. 

The Furnace Smells Like Sewer Odors 

Sewer gas smells quite similar to rotten eggs, so first rule out the potential for a natural gas leak. If that’s not the problem, your sewer lines could have an issue, such as a dry trap or sewer leak. Try pouring water down all your 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 Atmostemp Service Experts for Furnace Repair 

When in doubt, contact an HVAC technician to assess and repair your furnace. At Atmostemp Service Experts, we deliver 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 all options. 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 Atmostemp Service Experts office today.