Why Your Furnace Has a Strange Smell

As the weather gets colder and you swap from cooling to heating your home, you might be worried about unusual furnace smells floating in the air. Find out what the most common furnace smells could mean and how proactive you should be about them. 

The Furnace Smells Musty 

Musty furnace odors almost always imply mold growth hiding in the HVAC system. To avoid exposing your family to allergy-inducing mold, handle this problem as quickly as possible. 

A clogged air filter can encourage mold, so eliminating the smell could be as simple as getting a new filter. If that fails to remove the smell, the AC evaporator coil mounted near the furnace could be the culprit. This component accumulates condensation, which could induce mold growth. You’ll want a professional’s help to check and clean the evaporator coil. When this still doesn’t help, take a look at scheduling air duct cleaning. This service eliminates hidden mold, regardless of where it’s growing in your air ducts. 

The Furnace Smells Like Spoiled Eggs 

This is one of the most concerning furnace smells because it probably suggests a gas leak. The utility company adds a particular substance called mercaptan to the natural gas supply to make leaks easier to notice. 

If you recognize a rotten egg smell near your furnace or out of your air ducts, switch off the heater right away. If you can find where the main gas supply valve is, shut that off also. Then, leave the house and dial 911, followed by your gas company. Don’t go back in 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 to64} the furnace, this may mean the heat exchanger is cracked. This important component houses68} combustion fumes, like carbon monoxide, so cracks may allow unsafe levels of CO gas into your home. 

Carbon monoxide poisoning could be fatal, so switch 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 responsible. For your health and safety going forward, see to it that you have reliable CO detectors on each floor of your home. 

The Furnace Smells Dusty 

When you start the furnace for the first time after a while, you can 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 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 to the exterior. A smoky smell will sometimes mean the flue is clogged, and now fumes are settling back into your home. The odor might eventually reach the entire house, endangering your family’s health if you ignore it. So turn off the furnace and contact a professional straightaway 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 make an appearance. A faulty fan motor is also possible. If you don’t tackle the problem, an electrical fire may start, or your furnace could experience irreparable damage. Turn off the heating system right away and contact an HVAC technician for help identifying and repairing this unusual furnace smell. 

The Furnace Has an Oily Smell 

If you have an oil furnace, you could notice this odor whenever the oil filter becomes blocked up. Try replacing it to see if that resolves the problem. If the smell persists for more than 24 hours after carrying out this step, it might suggest an oil leak. You’ll need help from an HVAC expert to address this problem. 

The Furnace Reeks of Sewer Odors 

Sewer gas smells very 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, such as a dry trap or sewer leak. Pour water down all your drains, including the basement floor drain, to replenish dried-out sewer traps. If the smell persists, you should contact a sewer line repair company. 

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

If you’re still unsure, get in touch with an HVAC technician to examine and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we perform complete diagnostic services to determine the problem before the work begins. Then, we recommend the most viable, cost-effective repairs, alongside an up-front estimate for all options. Our ACE-certified technicians can handle 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 Service Experts Heating, Air Conditioning & Plumbing office today. 

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