Why Your Furnace Has a Strange Smell

As the weather turns cold and you swap from cooling to heating your home, you might be worried about weird furnace smells filling 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 usually indicate mold growth somewhere in the HVAC system. To avoid subjecting your family to allergy-inducing mold, handle this problem as soon as possible. 

A damp air filter can harbor mold, so wiping out the smell might be as easy as replacing the filter. If that doesn’t work, the AC evaporator coil mounted near the furnace could be to blame. This component gathers condensation, which could trigger mold growth. You’ll be better off with a professional’s help to inspect and clean the evaporator coil. When all else fails, consider requesting air duct cleaning. This service eliminates hidden mold, no matter where it’s growing in your air ducts. 

The Furnace Smells Like Rotten Eggs 

This is one of the most concerning furnace smells due to the fact that it most likely suggests a gas leak. The utility company adds a useful substance known as mercaptan to the natural gas supply to make leaks easier to notice. 

If you notice 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, shut that off as well. Then, evacuate your home and call 911, followed by 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 detect a sour smell that stings your nose while standing close to64} the furnace, this could mean the heat exchanger has cracked. This essential component houses68} combustion fumes, including carbon monoxide, so a crack could pump unsafe levels of CO gas into your home. 

Carbon monoxide poisoning has the potential to be fatal, so shut off your furnace right away if you detect 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, make sure you have working CO detectors on every floor of your home. 

The Furnace Smells Dusty 

When you fire up 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 backdrafting into your home. The odor may permeate the entire house, jeopardizing your family’s health if you ignore it. So shut down the furnace and contact a professional right away to arrange for 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 failing fan motor is also possible. If you don’t tackle the problem, an electrical fire could start, or your furnace could experience irreparable damage. Turn off the heating system immediately and call an HVAC technician for help troubleshooting and repairing this weird furnace smell. 

The Furnace Has an Oily Smell 

If you have an oil furnace, you may notice this odor if the oil filter becomes clogged. Try replacing it to find out if that fixes the problem. If the smell lingers for more than a day after taking care of this step, it could indicate an oil leak. You’ll be better off with help from an HVAC expert to fix this problem. 

The Furnace Smell Resembles Sewer Odors 

Sewer gas smells quite similar to rotten eggs, so first determine the possibility of 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. Flush water down all your drains, including the basement floor drain, to fill dried-up sewer traps. If the smell lingers, you’ll need to contact a sewer line repair company. 

Contact Neal Harris Service Experts for Furnace Repair 

When in doubt, get in touch with an HVAC technician to assess and repair your furnace. At Neal Harris Service Experts, we offer complete diagnostic services to pinpoint the problem before the work begins. Then, we recommend the most viable, cost-effective repairs, as well as an up-front estimate for every option. Our ACE-certified technicians can resolve just about any heating repair, 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 Neal Harris Service Experts office today.