Why Your Furnace Has a Strange Smell

As the weather cools down and you switch from cooling to heating your home, some homeowners are worried about unusual furnace smells filling the air. Learn about what the most common furnace smells mean and how proactive you should be about them.

The Furnace Smells Musty

Musty furnace odors generally suggest mold growth somewhere in the HVAC system. To avoid exposing your family to mold and mildew spores, tackle this problem as soon as possible.

A damp air filter can encourage mold, so wiping out the smell might be as straightforward as replacing the filter. If that doesn't help, the AC evaporator coil placed near the furnace might be the culprit. This component collects condensation, which could induce mold growth. You'll be better off with a professional’s help to inspect and clean the evaporator coil. When this still doesn't help, consider scheduling air duct cleaning. This service removes hidden mold, regardless of where it's hiding in your ductwork.

The Furnace Smells Like Spoiled Eggs

This is one of the most concerning furnace smells due to the fact that it most likely implies 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 recognize a rotten egg smell close to your furnace or originating from your vents, switch off the heater right away. If you can find where the main gas supply valve is, shut that off too. Then, get out of the house and call 911, in addition to your gas company. Don’t enter 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, including carbon monoxide, so cracks may allow unsafe levels of CO gas into your home.

Carbon monoxide poisoning could be lethal, so switch off your furnace as soon as possible 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 fire up the furnace for the first time each fall, you probably expect a dusty odor to appear for a brief moment. 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 24 hours, you don'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 could mean the flue is clogged, and now fumes are flowing back into your home. The odor may permeate the entire house, jeopardizing your family’s health if you neglect it. So shut down the furnace and contact a professional straightaway to schedule a repair.

The Furnace Smells Like It's 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 address 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 unpleasant furnace smell.

The Furnace Has an Oily Smell

If you have an oil furnace, you could detect this smell whenever the oil filter becomes blocked up. Try replacing it to find out if that fixes the problem. If the smell lingers for more than 24 hours after carrying out this step, it could indicate an oil leak. You'll be better off with help from an HVAC specialist to handle this problem.

The Furnace Smells Like Sewer Odors

Sewer gas smells very similar to spoiled eggs, so first determine the potential for a natural gas leak. If that’s not the issue, your home's sewer lines may have an issue, like a dry trap or sewer leak. Pour water down all your drains, including the basement floor drain, to refresh dried-out sewer traps. If the smell lingers, you’ll need to contact a sewer line repair company.

Contact Service Experts Heating & Air Conditioning for Furnace Repair

If you're still uncertain, contact an HVAC technician to assess and repair your furnace. At Service Experts Heating & Air Conditioning, we offer comprehensive diagnostic services to pinpoint the problem before we figure out the best solution. Then, we encourage the most viable, cost-effective repairs, as well as 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 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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