Why Your Furnace Has a Strange Smell

As the weather turns cold and you transition from cooling to heating your home, you might be worried about unusual furnace smells floating in the air. Learn about what the most common furnace smells mean and how worried you should be about them. 

The Furnace Smells Musty 

Musty furnace odors generally indicate mold growth someplace in the HVAC system. To avoid subjecting your family to allergy-inducing mold, tackle this problem right away. 

A damp air filter can harbor mold, so wiping out the smell might be as simple as replacing the filter. If that doesn’t help, the AC evaporator coil mounted near the furnace could be the root of the problem. This component collects condensation, which could trigger mold growth. You’ll be better off with a professional’s help to examine and clean the evaporator coil. When the problem still won’t go away, take a look at requesting air duct cleaning. This service cleans away hidden mold, regardless of where it’s growing in your ductwork. 

The Furnace Smells Like Rotting Eggs 

This is one of the most concerning furnace smells due to the fact that it frequently indicates a gas leak. The utility company puts in a special substance known as mercaptan to the natural gas supply to make leaks easier to detect. 

If you detect a rotten egg smell near your furnace or originating from your air ducts, switch off the heater right away. If you know where the main gas supply valve is, shut that off as well. Then, get out of the house and call 911, in addition to your gas company. Don’t reenter the house until a professional tells you it’s safe. 

The Furnace Has a Sour Stench 

If you detect a sour smell that stings your nose while close to64} the furnace, this might mean the heat exchanger is cracked. This essential component safely contains68} combustion fumes, including carbon monoxide, so cracks could pump unsafe levels of CO gas into your home. 

Carbon monoxide poisoning could be fatal, so shut off your furnace immediately if you notice a sour odor. Then, reach out to an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is responsible. For your continued safety going forward, ensure you have reliable CO detectors on every floor of your home. 

The Furnace Smells Dusty 

When you start the furnace for the first time every fall, you should expect a dusty odor to fill the house for a few minutes. This is the smell of six months’ worth of dust burning away as the furnace wakes up. As long as the smell disperses within 24 hours, 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 can mean the flue is blocked, and now fumes are backdrafting into your home. The odor may permeate the entire house, endangering your family’s health if you ignore it. 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 burned electrical components are the most plausible reason for a burning plastic smell to come from your furnace. A malfunctioning fan motor is another common cause. If you don’t tackle the problem, an electrical fire may start, or your furnace could experience irreparable damage. Disable the heating system immediately and call an HVAC technician for help diagnosing and repairing this unpleasant furnace smell. 

The Furnace Has an Oily Smell 

If you have an oil furnace, you may detect this smell when the oil filter becomes clogged. Try replacing it to see if that resolves the problem. If the smell lingers for more than a day after taking care of this step, it could suggest an oil leak. You’ll be better off with help from an HVAC expert to address this problem. 

The Furnace Reeks of Sewer Odors 

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

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

If you’re still unsure, contact an HVAC technician to assess and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we offer complete diagnostic services to identify the problem before we figure out the best solution. Then, we encourage the most viable, cost-effective repairs, along with an up-front estimate for every option. Our ACE-certified technicians can manage just about any heating repair, 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 Service Experts Heating, Air Conditioning & Plumbing office today. 

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