Why Your Furnace Has a Strange Smell

As the weather gets colder and you swap from cooling to heating your home, you may be worried about strange furnace smells filling the air. Learn about what the most common furnace smells mean and how proactive you should be about each one. 

The Furnace Smells Musty 

Musty furnace smells almost always suggest mold growth hiding in the HVAC system. To avoid subjecting your family to allergy-inducing mold, handle this problem as soon as possible. 

A wet air filter can encourage mold, so getting rid of the smell could be as straightforward as getting a new filter. If that fails to remove the smell, the AC evaporator coil mounted near the furnace might be the root of the problem. This component collects condensation, which could induce mold growth. You’ll want a professional’s help to inspect and clean the evaporator coil. When this still doesn’t help, take a look at requesting air duct cleaning. This service cleans away hidden mold, no matter where it’s growing in your ventilation. 

The Furnace Smells Like Rotting Eggs 

This is one of the most nerve-wracking furnace smells because it frequently suggests 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 coming from your ductwork, switch off the heater straightaway. If you remember where the main gas supply valve is placed, shut that off as well. Then, get out of the house 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 discover a sour smell that stings your nose while standing near64} the furnace, this might mean the heat exchanger cracked open. This important component safely contains68} combustion fumes, such as carbon monoxide, so a crack could spew unsafe levels of CO gas into your home. 

Carbon monoxide poisoning could be deadly, so turn off your furnace immediately if you recognize 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, make sure 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 each fall, you probably expect a dusty odor to fill the house 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 dissipates 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 could mean the flue is blocked, and now fumes are settling back into your home. The odor can reach through the entire house, risking your family’s health if you let it continue. So shut down the furnace and contact a professional straightaway to arrange for repair. 

The Furnace Smell Resembles Burning Plastic 

Overheating and melting electrical components are the most likely reason for a burning plastic smell to make an appearance. A faulty fan motor is another possibility. If you don’t correct the problem, an electrical fire may start, or your furnace could suffer from irreparable damage. Shut off the heating system right away and call an HVAC technician for help diagnosing and repairing this weird furnace smell. 

The Furnace Has an Oily Smell 

If you own an oil furnace, you might detect this smell whenever the oil filter becomes clogged. Try replacing it to determine if that resolves the problem. If the smell remains for more than one day after completing this step, it may suggest an oil leak. You should get help from an HVAC professional to address this problem. 

The Furnace Smell Resembles Sewer Odors 

Sewer gas smells quite similar to rotting eggs, so first rule out the potential for a natural gas leak. If that’s not the issue, your sewer lines might have an issue, like a dry trap or sewer leak. Try pouring water down your own drains, including the basement floor drain, to fill dried-up sewer traps. If the smell sticks around, go ahead and contact a sewer line repair company. 

Contact Service Experts Heating, Air Conditioning & Plumbing for Furnace Repair 

If you’re still uncertain, call an HVAC technician to examine and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we deliver complete diagnostic services to determine the problem before the work begins. Then, we recommend the most viable, cost-effective repairs, along with an up-front estimate for all options. 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 & Plumbing office today. 

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