Why Your Furnace Has a Strange Smell

As the weather gets colder 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, address this problem as soon as possible. 

A damp air filter can harbor mold, so eliminating 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 to blame. This component gathers condensation, which could trigger mold growth. You’ll need a professional’s help to examine and clean the evaporator coil. When all else fails, consider investing in 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 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 notice a rotten egg smell near your furnace or coming from your vents, switch off the heater immediately. If you know where the main gas supply valve is, shut that off too. Then, evacuate your home and contact 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 vital component safely contains68} combustion fumes, including 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 notice 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 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 correct 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 odor if the oil filter becomes clogged. Try replacing it to determine 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 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, the 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 dried-out sewer traps. If the smell persists, you should contact a sewer line repair company. 

Contact Fras-Air/General Service Experts for Furnace Repair 

When in doubt, contact an HVAC technician to check and repair your furnace. At Fras-Air/General 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 Fras-Air/General Service Experts office today.