Why Your Furnace Has a Strange Smell

As the weather cools down and you swap from cooling to heating your home, you might be worried about weird furnace smells in the air. Find out what the most common furnace smells mean and how concerned you should be about them.

The Furnace Smells Musty

Musty furnace smells generally indicate mold growth somewhere in the HVAC system. To avoid subjecting your family to mold and mildew spores, tackle this problem as quickly as possible.

A damp air filter can lead to mold, so wiping out the smell can be as simple as replacing the filter. If that doesn't help, the AC evaporator coil fastened near the furnace could be the culprit. This component gathers condensation, which could induce mold growth. You'll want a professional’s help to check and clean the evaporator coil. When the problem still won't go away, take a look at scheduling air duct cleaning. This service removes hidden mold, no matter where it’s growing in your air ducts.

The Furnace Smells Like Spoiled Eggs

This is one of the most nerve-wracking furnace smells since it most likely indicates a gas leak. The utility company adds a special substance called mercaptan to the natural gas supply to make leaks easier to detect.

If you recognize a rotten egg smell near your furnace or originating from your air ducts, shut down the heater right away. If you know where the main gas supply valve is located, shut that off too. Then, evacuate your home and call 911, in addition to your gas company. Don’t reenter the house until a professional confirms it’s safe.

The Furnace Has a Sour Stench

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

Carbon monoxide poisoning has the potential to be fatal, so turn 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 to blame. 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 little while. This is the smell of six months’ worth of dust burning away as the furnace wakes up. As long as the smell goes away 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 safely out of your home. A smoky smell will sometimes mean the flue is blocked, and now fumes are settling back into your home. The odor may permeate the entire house, jeopardizing your family’s health if you let it continue. So turn off the furnace and get in touch with a professional right away to request furnace repair.

The Furnace Smell Resembles Burning Plastic

Overheating and melted electrical components are the most plausible reason for a burning plastic smell to appear. A failing fan motor is another possibility. If you don’t tackle the problem, an electrical fire could start, or your furnace could suffer from irreparable damage. Turn off the heating system as soon as possible and contact an HVAC technician for help troubleshooting and repairing this unusual furnace smell.

The Furnace Has an Oily Smell

If you use an oil furnace, you may pick up on this odor if the oil filter becomes clogged. Try replacing it to find out if that fixes the problem. If the smell lingers for more than one day after taking care of this step, it may indicate an oil leak. You’ll need help from an HVAC expert to address this problem.

The Furnace Smell Resembles Sewer Odors

Sewer gas smells very similar to rotten eggs, so first rule out the possibility of a natural gas leak. If that’s not the source, your home's sewer lines could have an issue, for example a dry trap or sewer leak. Try pouring water down your own drains, including the basement floor drain, to fill dry sewer traps. If the smell sticks around, you should contact a sewer line repair company.

Contact Matz-Rightway for Furnace Repair

When in doubt, get in touch with an HVAC technician to check and repair your furnace. At Matz-Rightway, we perform thorough diagnostic services to determine the problem before we figure out the best solution. Then, we recommend the most viable, cost-effective repairs, alongside an up-front estimate for each 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. To learn more about why your furnace smells bad or to request furnace repair near you, please contact your local Matz-Rightway office today.

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