Why Your Furnace Has a Strange Smell

As the weather gets colder and you transition from cooling to heating your home, some homeowners are worried about strange furnace smells filling the air. Learn about what the most common furnace smells could suggest and how proactive you should be about each one. 

The Furnace Smells Musty 

Musty furnace smells usually suggest mold growth hiding in the HVAC system. To avoid subjecting your family to mold and mildew spores, address this problem as quickly as possible. 

A damp air filter can harbor mold, so wiping out the smell can be as easy as replacing the filter. If that fails to remove the smell, the AC evaporator coil placed near the furnace may be to blame. This component collects condensation, which could trigger mold growth. You’ll need a professional’s help to examine and clean the evaporator coil. When this still doesn’t help, start thinking about investing in air duct cleaning. This service cleans away hidden mold, no matter where it’s hiding in your ductwork. 

The Furnace Smells Like Rotten Eggs 

This is one of the most concerning furnace smells due to the fact that it probably implies a gas leak. The utility company puts in a useful substance called 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 vents, switch off the heater straightaway. If you remember where the main gas supply valve is located, shut that off as well. Then, get out of the house and dial 911, as well as your gas company. Don’t reenter the house until a professional confirms it’s safe. 

The Furnace Has a Sour Stench 

If you detect a sour smell that stings your nose while standing near64} the furnace, this might mean the heat exchanger cracked open. This essential component safely contains68} combustion fumes, including carbon monoxide, so a crack may allow unsafe levels of CO gas into your home. 

Carbon monoxide poisoning can be lethal, 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 the culprit. For your health and safety going forward, make sure you have functional CO detectors on each floor of your home. 

The Furnace Smells Dusty 

When you turn on the furnace for the first time every fall, you probably expect a dusty odor to appear 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 a day, 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 to the exterior. A smoky smell will sometimes mean the flue is blocked, and now fumes are backdrafting 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 right away to schedule a repair. 

The Furnace Smells Like Burning Plastic 

Overheating and melting electrical components are the most common 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 end up with irreparable damage. Disable the heating system immediately 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 may pick up on this smell when the oil filter becomes blocked up. Try replacing it to see if that addresses the problem. If the smell remains for more than 24 hours after completing this step, it may indicate an oil leak. You’ll be better off with help from an HVAC expert to address this problem. 

The Furnace Smells Like Sewer Odors 

Sewer gas smells very similar to rotten eggs, so first determine the potential for a natural gas leak. If that’s not the issue, your sewer lines may have an issue, for example a dry trap or sewer leak. Pour water down all your drains, including the basement floor drain, to fill dry sewer traps. If the smell lingers, you’ll need to 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 check and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we deliver comprehensive diagnostic services to identify the problem before repairs begin. 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 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.