Why Your Furnace Has a Strange Smell

As the weather gets colder and you transition from cooling to heating your home, you may be worried about unusual furnace smells in the air. Learn about what the most common furnace smells could mean and how concerned you should be about them.

The Furnace Smells Musty

Musty furnace smells generally indicate mold growth hiding in the HVAC system. To avoid subjecting your family to allergy-inducing mold, handle this problem as quickly as possible.

A damp air filter can encourage mold, so getting rid of the smell could be as simple as swapping out filter. If that doesn’t work, the AC evaporator coil fastened near the furnace could be to blame. 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 this still doesn't help, take a look at scheduling air duct cleaning. This service eliminates hidden mold, no matter where it’s growing in your ventilation.

The Furnace Smells Like Rotten Eggs

This is one of the most worrisome furnace smells due to the fact that it most likely indicates a gas leak. The utility company adds a particular substance known as mercaptan to the natural gas supply to make leaks easier to detect.

If you notice a rotten egg smell close to your furnace or out of your air ducts, shut down the heater immediately. If you know where the main gas supply valve is located, shut that off too. Then, leave the house and call 911, followed by your gas company. Don’t go back in 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 to the furnace, this might mean the heat exchanger is cracked. This essential component houses combustion fumes, such as 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 immediately if you recognize 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 continued safety going forward, ensure you have reliable CO detectors on all floors 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 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 up and out of your home. A smoky smell will sometimes mean the flue is backed up, and now fumes are settling back into your home. The odor can reach through the entire house, jeopardizing your family’s health if you let it continue. So shut down the furnace and call a professional straightaway to schedule a repair.

The Furnace Smells Like Burning Plastic

Overheating and melted electrical components are the most plausible reason for a burning plastic smell to come from your furnace. A faulty fan motor is another common cause. If you don’t tackle the problem, an electrical fire could start, or your furnace could experience irreparable damage. Turn off the heating system right away and call an HVAC technician for help identifying and repairing this unpleasant furnace smell.

The Furnace Has an Oily Smell

If you have an oil furnace, you could detect this stench if the oil filter becomes blocked up. Try replacing it to determine if that addresses the problem. If the smell persists for more than one day after taking care of this step, it may imply an oil leak. You should get help from an HVAC specialist to fix this problem.

The Furnace Reeks of Sewer Odors

Sewer gas smells very similar to rotten eggs, so first eliminate the potential for a natural gas leak. If that’s not the issue, the sewer lines could have an issue, such as a dry trap or sewer leak. Try pouring water down the drains, including the basement floor drain, to replenish dry sewer traps. If the smell sticks around, go ahead and contact a sewer line repair company.

Contact Comfortech Service Experts for Furnace Repair

When in doubt, contact an HVAC technician to check and repair your furnace. At Comfortech Service Experts , we deliver thorough diagnostic services to identify the problem before the work begins. Then, we recommend the most viable, cost-effective repairs, alongside an up-front estimate for all options. Our ACE-certified technicians can handle 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 Comfortech Service Experts office today.

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