Why Your Furnace Has a Strange Smell

As the weather turns cold and you switch from cooling to heating your home, you might be worried about weird furnace smells floating 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 almost always 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 getting rid of 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 the culprit. This component gathers condensation, which could induce mold growth. You’ll be better off with a professional’s help to inspect and clean the evaporator coil. When all else fails, consider scheduling air duct cleaning. This service removes 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 indicates 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, shut down the heater right away. If you know where the main gas supply valve is, shut that off as well. Then, evacuate your home and dial 911, followed by your gas company. Don’t reenter 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 houses68} combustion fumes, such as carbon monoxide, so cracks could pump unsafe levels of CO gas into your home. 

Carbon monoxide poisoning can 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 fire up the furnace for the first time after a while, you can expect a dusty odor to show up for a few minutes. This is the smell of six months’ worth of dust burning away as the furnace wakes from its summer slumber. As long as the smell dissipates 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 could mean the flue is blocked, and now fumes are flowing back into your home. The odor may permeate the entire house, jeopardizing your family’s health if you ignore it. So switch off the furnace and call a professional right away to arrange for 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 common cause. If you don’t address the problem, an electrical fire could start, or your furnace could experience irreparable damage. Disable 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 own an oil furnace, you may pick up on 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’ll need help from an HVAC expert to address this problem. 

The Furnace Reeks of Sewer Odors 

Sewer gas smells quite similar to rotten eggs, so first rule out the possibility of a natural gas leak. If that’s not the problem, the 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, go ahead and contact a sewer line repair company. 

Contact Matz-Rightway for Furnace Repair 

When in doubt, contact an HVAC technician to assess and repair your furnace. At Matz-Rightway, we offer comprehensive diagnostic services to pinpoint the problem before repairs begin. Then, we suggest 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 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 Matz-Rightway office today.