Why Your Furnace Has a Strange Smell

As the weather turns cold and you transition from cooling to heating your home, some homeowners are worried about weird furnace smells in the air. Find out what the most common furnace smells could suggest and how proactive you should be about them.

The Furnace Smells Musty

Musty furnace odors generally imply mold growth someplace in the HVAC system. To avoid exposing your family to mold and mildew spores, tackle this problem as soon as possible.

A clogged air filter can harbor mold, so getting rid of the smell could be as straightforward as swapping out filter. If that doesn’t work, the AC evaporator coil mounted near the furnace could be to blame. This component accumulates condensation, which will sometimes stimulate mold growth. You'll want a professional’s help to examine and clean the evaporator coil. When all else fails, take a look at requesting air duct cleaning. This service cleans away hidden mold, no matter where it's hiding in your air ducts.

The Furnace Smells Like Rotting Eggs

This is one of the most worrisome 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 easier to notice.

If you recognize a rotten egg smell close to your furnace or coming from your air ducts, switch off the heater right away. If you remember where the main gas supply valve is located, shut that off also. Then, leave the house and call 911, in addition to your gas company. Don’t enter 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 close to the furnace, this may mean the heat exchanger has cracked. This vital component contains combustion fumes, including carbon monoxide, so a crack might pump unsafe levels of CO gas into your home.

Carbon monoxide poisoning has the potential to be lethal, so turn off your furnace as soon as possible if you notice 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 functional CO detectors on all floors of your home.

The Furnace Smells Dusty

When you start 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 away as the furnace wakes from its summer slumber. As long as the smell disperses 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 ignore it. So switch off the furnace and call a professional as soon as you can to request furnace repair.

The Furnace Smell Resembles Burning Plastic

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

The Furnace Has an Oily Smell

If you have an oil furnace, you might notice this stench when the oil filter becomes clogged. Try replacing it to see if that resolves the problem. If the smell lingers for more than one day after carrying out this step, it could indicate an oil leak. You should get help from an HVAC specialist to handle this problem.

The Furnace Smell Resembles 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 may have an issue, such as a dry trap or sewer leak. Flush water down the drains, including the basement floor drain, to refresh dried-out sewer traps. If the smell persists, you should contact a sewer line repair company.

Contact Neal Harris Service Experts for Furnace Repair

If you're still unsure, call an HVAC technician to assess and repair your furnace. At Neal Harris Service Experts, we perform thorough diagnostic services to determine the problem before repairs begin. Then, we encourage the most viable, cost-effective repairs, along with an up-front estimate for each option. Our ACE-certified technicians can handle just about any heating problem, and we back our work with a 100% satisfaction guarantee for one year. To learn more about why your furnace smells bad or to request furnace repair near you, please contact your local Neal Harris Service Experts office today.

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