Why Your Furnace Has a Strange Smell

As the weather turns cold and you transition 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, tackle this problem as soon as possible. 

A clogged air filter can harbor mold, so eliminating the smell might be as easy as replacing the filter. If that doesn’t work, the AC evaporator coil placed near the furnace could be to blame. This component gathers condensation, which could 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 eliminates hidden mold, no matter where it’s growing in your ductwork. 

The Furnace Smells Like Rotten Eggs 

This is one of the most nerve-wracking furnace smells because 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 notice a rotten egg smell near your furnace or coming from your vents, shut 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 go back in 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 has cracked. This vital component contains68} combustion fumes, including carbon monoxide, so a cracked heat exchanger could pump unsafe levels of CO gas into your home. 

Carbon monoxide poisoning can be fatal, so shut off your furnace right away if you recognize a sour odor. Then, contact 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 turn on the furnace for the first time after a while, you can expect a dusty odor to fill the house for a few minutes. 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 goes away 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 will sometimes mean the flue is backed up, 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 turn off the furnace and get in touch with a professional right away to schedule a repair. 

The Furnace Smells Like Burning Plastic 

Overheating and melting electrical components are the most likely reason for a burning plastic smell to come from your furnace. 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. Turn off the heating system immediately and call an HVAC technician for help diagnosing and repairing this weird furnace smell. 

The Furnace Has an Oily Smell 

If you own an oil furnace, you could detect this smell 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 carrying out this step, it could indicate an oil leak. You’ll need 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 rule out the potential for 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 fill dried-out sewer traps. If the smell persists, go ahead and contact a sewer line repair company. 

Contact Rolf Griffin Service Experts for Furnace Repair 

When in doubt, contact an HVAC technician to check and repair your furnace. At Rolf Griffin Service Experts, we perform comprehensive diagnostic services to pinpoint the problem before we figure out the best solution. 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 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 Rolf Griffin Service Experts office today.