Why Your Furnace Has a Strange Smell

As the weather cools down and you switch from cooling to heating your home, you might be worried about unusual 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, address this problem as soon as possible. 

A clogged air filter can harbor mold, so eliminating the smell might be as simple as replacing the filter. If that doesn’t work, the AC evaporator coil placed near the furnace could be the root of the problem. This component collects condensation, which will sometimes trigger mold growth. You’ll want a professional’s help to check 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 ductwork. 

The Furnace Smells Like Rotten Eggs 

This is one of the most concerning furnace smells because it most likely implies a gas leak. The utility company adds a useful substance known as mercaptan to the natural gas supply to make leaks more easily detected. 

If you notice a rotten egg smell around your furnace or coming from your vents, shut off the heater immediately. If you know where the main gas supply valve is located, shut that off also. Then, evacuate your home and call 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 close to64} the furnace, this could mean the heat exchanger is cracked. This vital component houses68} combustion fumes, like 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, 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 after a while, 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 one 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 clogged, and now fumes are backdrafting into your home. The odor may permeate the entire house, endangering your family’s health if you neglect it. So switch off the furnace and call 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 make an appearance. A failing fan motor is another possibility. 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 have an oil furnace, you could detect this stench if 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 carrying out this step, it could indicate an oil leak. You should get 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 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-out sewer traps. If the smell sticks around, you’ll need to contact a sewer line repair company. 

Contact Falso Service Experts for Furnace Repair 

When in doubt, contact an HVAC technician to check and repair your furnace. At Falso Service Experts, we perform comprehensive diagnostic services to pinpoint the problem before repairs begin. Then, we recommend 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 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 Falso Service Experts office today.