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 weird furnace smells floating in the air. Find out what the most common furnace smells mean and how proactive you should be about each one.

The Furnace Smells Musty

Musty furnace smells usually indicate mold growth someplace in the HVAC system. To avoid subjecting your family to these microorganisms, tackle this problem as soon as possible.

A damp air filter can harbor mold, so wiping out the smell could be as straightforward as swapping out filter. If that fails to remove the smell, the AC evaporator coil fastened near the furnace may be to blame. This component collects condensation, which can stimulate mold growth. You'll want a professional’s help to inspect and clean the evaporator coil. When the problem still won't go away, take a look at requesting air duct cleaning. This service eliminates hidden mold, regardless of where it’s growing in your ventilation.

The Furnace Smells Like Spoiled Eggs

This is one of the most concerning furnace smells since it probably implies a gas leak. The utility company adds a particular substance called mercaptan to the natural gas supply to make leaks more easily detected.

If you detect a rotten egg smell near your furnace or originating from your air ducts, shut off the heater immediately. If you know where the main gas supply valve is placed, shut that off also. Then, evacuate your home and call 911, in addition to 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 discover a sour smell that stings your nose while standing near the furnace, this may mean the heat exchanger has cracked. This important component contains combustion fumes, such as carbon monoxide, so a cracked heat exchanger could spew unsafe levels of CO gas into your home.

Carbon monoxide poisoning has the potential to be lethal, so turn off your furnace immediately if you detect 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 each floor of your home.

The Furnace Smells Dusty

When you turn on the furnace for the first time every fall, you should expect a dusty odor to appear for a few minutes. 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 goes away within one 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 clogged, and now fumes are settling back into your home. The odor can reach through the entire house, jeopardizing your family’s health if you neglect it. So shut down the furnace and contact a professional right away to request furnace repair.

The Furnace Smells Like It's Burning Plastic

Overheating and melted 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 might start, or your furnace could experience irreparable damage. Disable the heating system as soon as possible and call an HVAC technician for help identifying and repairing this unusual furnace smell.

The Furnace Has an Oily Smell

If you use an oil furnace, you might notice this smell when the oil filter becomes blocked up. Try replacing it to determine if that resolves the problem. If the smell remains for more than 24 hours after taking care of this step, it might imply an oil leak. You'll be better off with help from an HVAC professional to address this problem.

The Furnace Reeks of Sewer Odors

Sewer gas smells quite similar to spoiled eggs, so first rule out the potential for a natural gas leak. If that’s not the problem, your sewer lines might have an issue, like a dry trap or sewer leak. Flush water down the drains, including the basement floor drain, to replenish dried-up sewer traps. If the smell lingers, you should contact a sewer line repair company.

Contact Service Experts Heating & Air Conditioning for Furnace Repair

If you're still uncertain, call an HVAC technician to check and repair your furnace. At Service Experts Heating & Air Conditioning, we offer thorough diagnostic services to determine the problem before repairs begin. Then, we suggest the most viable, cost-effective repairs, along with 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. 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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