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 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 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 damp air filter can harbor mold, so getting rid of 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 the culprit. This component accumulates condensation, which will sometimes 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 ductwork. 

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 detect. 

If you detect a rotten egg smell close to your furnace or coming from your vents, switch off the heater immediately. If you know where the main gas supply valve is placed, shut that off too. Then, evacuate your home and call 911, followed by your gas company. Don’t reenter 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 close to64} the furnace, this could mean the heat exchanger has cracked. This vital component safely contains68} combustion fumes, including carbon monoxide, so a cracked heat exchanger 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 functional CO detectors on each floor of your home. 

The Furnace Smells Dusty 

When you fire up the furnace for the first time each fall, you can expect a dusty odor to fill the house 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 settling back into your home. The odor may permeate the entire house, risking 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 plausible reason for a burning plastic smell to come from your furnace. A failing fan motor is another possibility. 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 identifying and repairing this unusual furnace smell. 

The Furnace Has an Oily Smell 

If you own an oil furnace, you could 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 could indicate an oil leak. You should get help from an HVAC expert to fix this problem. 

The Furnace Reeks of 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. Pour water down all your drains, including the basement floor drain, to replenish dry sewer traps. If the smell lingers, you’ll need to contact a sewer line repair company. 

Contact Robinson Service Experts for Furnace Repair 

When in doubt, call an HVAC technician to assess and repair your furnace. At Robinson Service Experts, we perform thorough diagnostic services to pinpoint the problem before the work begins. 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 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 Robinson Service Experts office today.