Why Your Furnace Has a Strange Smell

As the weather cools down and you swap from cooling to heating your home, some homeowners are worried about unusual 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 usually imply mold growth somewhere in the HVAC system. To avoid subjecting your family to these microorganisms, handle this problem right away.

A damp air filter can harbor mold, so eliminating the smell might be as straightforward as getting a new filter. If that doesn’t work, the AC evaporator coil fastened near the furnace may be the root of the problem. This component gathers condensation, which can trigger mold growth. You’ll need a professional’s help to inspect and clean the evaporator coil. When all else fails, consider scheduling air duct cleaning. This service eliminates hidden mold, no matter where it's hiding in your ventilation.

The Furnace Smells Like Rotten Eggs

This is one of the most nerve-wracking furnace smells since it frequently indicates a gas leak. The utility company puts in a particular substance called mercaptan to the natural gas supply to make leaks easier to notice.

If you notice a rotten egg smell near your furnace or coming from your vents, shut off the heater immediately. If you can find where the main gas supply valve is located, shut that off as well. Then, evacuate your home and call 911, followed by your gas company. Don’t enter the house until a professional confirms 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 may mean the heat exchanger is cracked. This important component houses combustion fumes, like carbon monoxide, so cracks may spew unsafe levels of CO gas into your home.

Carbon monoxide poisoning can be fatal, so shut off your furnace immediately if you detect a sour odor. Then, reach out to 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, ensure you have working CO detectors on every floor of your home.

The Furnace Smells Dusty

When you turn on the furnace for the first time every 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 up as the furnace wakes up. 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 safely 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 may permeate the entire house, jeopardizing your family’s health if you neglect it. So turn off the furnace and contact a professional right away to arrange for repair.

The Furnace Smell Resembles Burning Plastic

Overheating and melted electrical components are the most likely reason for a burning plastic smell to make an appearance. A malfunctioning fan motor is another common cause. If you don’t correct the problem, an electrical fire could start, or your furnace could suffer from irreparable damage. Shut off the heating system immediately and contact an HVAC technician for help diagnosing and repairing this unusual furnace smell.

The Furnace Has an Oily Smell

If you have an oil furnace, you might pick up on this stench whenever the oil filter becomes blocked up. Try replacing it to see if that fixes the problem. If the smell remains for more than one day after completing this step, it could suggest an oil leak. You should get help from an HVAC specialist to address this problem.

The Furnace Smells Like Sewer Odors

Sewer gas smells pretty similar to spoiled eggs, so first determine the potential for a natural gas leak. If that’s not the issue, the sewer lines could have an issue, for example a dry trap or sewer leak. Try pouring water down the drains, including the basement floor drain, to replenish dried-up sewer traps. If the smell sticks around, you’ll need to contact a sewer line repair company.

Contact A1 Chesney Service Experts for Furnace Repair

If you're still uncertain, get in touch with an HVAC technician to assess and repair your furnace. At A1 Chesney 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 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 A1 Chesney Service Experts office today.

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