Why Your Furnace Has a Strange Smell

As the weather turns cold and you swap from cooling to heating your home, you might be worried about strange furnace smells in the air. Find out what the most common furnace smells could suggest and how worried you should be about each one.

The Furnace Smells Musty

Musty furnace odors almost always indicate mold growth someplace in the HVAC system. To avoid exposing your family to these microorganisms, tackle this problem as soon as possible.

A wet air filter can lead to mold, so eliminating the smell can be as simple as getting a new filter. If that fails to remove the smell, the AC evaporator coil mounted near the furnace might be the culprit. This component collects condensation, which could trigger mold growth. You'll be better off with a professional’s help to examine and clean the evaporator coil. When this still doesn't help, take a look at requesting air duct cleaning. This service eliminates hidden mold, no matter where it's hiding in your air ducts.

The Furnace Smells Like Rotting Eggs

This is one of the most nerve-wracking furnace smells because it probably indicates a gas leak. The utility company adds a useful substance known as mercaptan to the natural gas supply to make leaks more easily detected.

If you detect a rotten egg smell close to your furnace or originating from your ductwork, switch off the heater straightaway. If you know where the main gas supply valve is, shut that off too. Then, leave the house and call 911, as well as your gas company. Don’t reenter the house until a professional confirms it’s safe.

The Furnace Has a Sour Stench

If you discover a sour smell that stings your nose while close to the furnace, this could mean the heat exchanger has cracked. This important component contains combustion fumes, such as carbon monoxide, so cracks could allow unsafe levels of CO gas into your home.

Carbon monoxide poisoning has the potential to be lethal, 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 the culprit. For your family's safety going forward, make sure you have reliable 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 should 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 up. As long as the smell dissipates within a day, 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 can mean the flue is backed up, and now fumes are settling back into your home. The odor might eventually reach the entire house, risking your family’s health if you neglect it. So switch off the furnace and call a professional right away to arrange for repair.

The Furnace Smell Resembles 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 also possible. If you don’t correct the problem, an electrical fire may start, or your furnace could end up with irreparable damage. Shut off the heating system as soon as possible and call an HVAC technician for help identifying and repairing this unpleasant furnace smell.

The Furnace Has an Oily Smell

If you use an oil furnace, you may notice this odor if the oil filter becomes clogged. Try replacing it to see if that addresses the problem. If the smell persists for more than a day after carrying out this step, it may suggest an oil leak. You'll be better off with help from an HVAC specialist to fix this problem.

The Furnace Reeks of Sewer Odors

Sewer gas smells very similar to rotting eggs, so first rule out the likelihood of a natural gas leak. If that’s not the issue, your home's sewer lines might have an issue, such as a dry trap or sewer leak. Try pouring water down your own drains, including the basement floor drain, to refresh dry sewer traps. If the smell persists, you should contact a sewer line repair company.

Contact Service Experts Heating & Air Conditioning for Furnace Repair

When in doubt, get in touch with an HVAC technician to check and repair your furnace. At Service Experts Heating & Air Conditioning, we deliver comprehensive diagnostic services to identify the problem before we figure out the best solution. Then, we encourage the most viable, cost-effective repairs, along with an up-front estimate for every option. Our ACE-certified technicians can manage just about any heating problem, and we back our work with a 100% satisfaction guarantee for one year. To ask questions about why your furnace smells bad or to request furnace repair near you, please contact your local Service Experts Heating & Air Conditioning office today.

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