Why Your Furnace Has a Strange Smell

As the weather turns cold and you transition from cooling to heating your home, you may be worried about weird furnace smells floating in the air. Learn about what the most common furnace smells could mean and how worried you should be about them.

The Furnace Smells Musty

Musty furnace odors almost always imply mold growth somewhere in the HVAC system. To avoid subjecting your family to mold and mildew spores, tackle this problem as soon as possible.

A clogged air filter can lead to mold, so eliminating the smell can be as straightforward as getting a new filter. If that doesn't help, the AC evaporator coil fastened near the furnace could be the root of the problem. This component collects condensation, which will sometimes stimulate mold growth. You’ll need a professional’s help to inspect and clean the evaporator coil. When this still doesn't help, take a look at requesting air duct cleaning. This service cleans away hidden mold, no matter where it’s growing in your ventilation.

The Furnace Smells Like Spoiled Eggs

This is one of the most concerning furnace smells due to the fact that it most likely implies a gas leak. The utility company puts in a special substance known as mercaptan to the natural gas supply to make leaks easier to detect.

If you detect a rotten egg smell close to your furnace or originating from your air ducts, shut off the heater straightaway. If you know where the main gas supply valve is, shut that off too. Then, evacuate your home and dial 911, as well as your gas company. Don’t enter the house until a professional can verify it’s safe.

The Furnace Has a Sour Stench

If you notice a sour smell that stings your nose while standing close to the furnace, this might mean the heat exchanger cracked open. This vital component contains combustion fumes, including carbon monoxide, so cracks could pump unsafe levels of CO gas into your home.

Carbon monoxide poisoning could be deadly, so turn off your furnace as soon as possible 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, see to it that you have working 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 probably expect a dusty odor to show up for a few minutes. 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 goes away within 24 hours, you shouldn't have anything 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 call a professional right away to request furnace repair.

The Furnace Smells Like Burning Plastic

Overheating and melted electrical components are the most likely 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 may start, or your furnace could suffer from irreparable damage. Shut off the heating system right away and contact an HVAC technician for help identifying and repairing this weird furnace smell.

The Furnace Has an Oily Smell

If you own an oil furnace, you could pick up on this odor whenever the oil filter becomes blocked up. Try replacing it to determine if that addresses the problem. If the smell lingers for more than 24 hours after completing this step, it could imply an oil leak. You should get help from an HVAC professional to handle this problem.

The Furnace Smell Resembles Sewer Odors

Sewer gas smells quite similar to rotting eggs, so first rule out the possibility of a natural gas leak. If that’s not the source, your sewer lines could have an issue, like 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 lingers, you should contact a sewer line repair company.

Contact Jack Nelson Service Experts for Furnace Repair

When in doubt, get in touch with an HVAC technician to assess and repair your furnace. At Jack Nelson Service Experts, we deliver thorough diagnostic services to determine the problem before the work begins. Then, we encourage the most viable, cost-effective repairs, along with an up-front estimate for every 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 Jack Nelson Service Experts office today.

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