Why Your Furnace Has a Strange Smell

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

The Furnace Smells Musty

Musty furnace smells generally imply mold growth somewhere in the HVAC system. To avoid exposing your family to mold and mildew spores, handle this problem right away.

A wet air filter can lead to mold, so eliminating the smell can be as easy as getting a new filter. If that doesn’t work, the AC evaporator coil mounted near the furnace could be the culprit. This component collects condensation, which can trigger mold growth. You’ll need a professional’s help to examine and clean the evaporator coil. When the problem still won't go away, consider investing in air duct cleaning. This service cleans away 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 because it frequently indicates a gas leak. The utility company puts in 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 down the heater right away. If you can find where the main gas supply valve is placed, shut that off as well. Then, get out of the house and call 911, as well as your gas company. Don’t go back in the house until a professional can verify 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 might mean the heat exchanger cracked open. This important component safely contains combustion fumes, like carbon monoxide, so a cracked heat exchanger may spew unsafe levels of CO gas into your home.

Carbon monoxide poisoning can be deadly, so shut off your furnace immediately if you notice a sour odor. Then, call an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is responsible. For your health and safety going forward, ensure you have functional CO detectors on every 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 show up 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 disperses 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 might eventually reach the entire house, jeopardizing your family’s health if you neglect it. So shut down the furnace and contact a professional straightaway to arrange for repair.

The Furnace Smells Like It's Burning Plastic

Overheating and melting electrical components are the most common reason for a burning plastic smell to make an appearance. A malfunctioning fan motor is another possibility. If you don’t address the problem, an electrical fire might start, or your furnace could experience irreparable damage. Disable the heating system immediately and contact an HVAC technician for help identifying and repairing this unpleasant furnace smell.

The Furnace Has an Oily Smell

If you own an oil furnace, you might pick up on this odor when the oil filter becomes clogged. Try replacing it to see if that fixes the problem. If the smell remains for more than a day after taking care of this step, it could indicate an oil leak. You'll be better off with help from an HVAC professional to address this problem.

The Furnace Smell Resembles Sewer Odors

Sewer gas smells quite similar to spoiled eggs, so first determine the possibility of a natural gas leak. If that’s not the issue, your sewer lines could have an issue, for example a dry trap or sewer leak. Pour water down your own drains, including the basement floor drain, to fill dry sewer traps. If the smell persists, go ahead and contact a sewer line repair company.

Contact Epperson Service Experts for Furnace Repair

If you're still uncertain, get in touch with an HVAC technician to check and repair your furnace. At Epperson Service Experts, we perform comprehensive diagnostic services to pinpoint the problem before the work begins. Then, we recommend the most viable, cost-effective repairs, as well as an up-front estimate for each option. Our ACE-certified technicians can handle just about any heating repair, 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 Epperson Service Experts office today.

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