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 usually imply 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 can be as easy as replacing the filter. If that doesn’t work, the AC evaporator coil mounted near the furnace could be the root of the problem. This component collects 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 scheduling air duct cleaning. This service cleans away 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 includes 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, shut off the heater straightaway. If you know where the main gas supply valve is, 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 standing near64} the furnace, this could mean the heat exchanger has cracked. This important component contains68} combustion fumes, including 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, 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 reliable 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 fill the house for a little while. This is the smell of six months’ worth of dust burning up as the furnace wakes from its summer slumber. As long as the smell disperses 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 could mean the flue is backed up, and now fumes are backdrafting into your home. The odor may permeate the entire house, endangering your family’s health if you ignore it. So turn off the furnace and call 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 another possibility. If you don’t correct 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 use an oil furnace, you might notice this smell 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 imply an oil leak. You’ll be better off with help from an HVAC expert to handle this problem. 

The Furnace Smells Like Sewer Odors 

Sewer gas smells quite similar to rotten eggs, so first rule out the likelihood of a natural gas leak. If that’s not the problem, your home’s 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 dry sewer traps. If the smell lingers, you’ll need to contact a sewer line repair company. 

Contact Comfort Masters Service Experts for Furnace Repair 

When in doubt, call an HVAC technician to assess and repair your furnace. At Comfort Masters Service Experts, we perform complete 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 each 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 Comfort Masters Service Experts office today.