Why Your Furnace Has a Strange Smell

As the weather cools down and you swap from cooling to heating your home, you may be worried about unusual furnace smells filling the air. Find out what the most common furnace smells mean and how concerned you should be about each one. 

The Furnace Smells Musty 

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

A clogged air filter can lead to mold, so wiping out the smell might be as easy as getting a new filter. If that doesn’t help, the AC evaporator coil placed near the furnace may be to blame. This component accumulates condensation, which can stimulate mold growth. You’ll need a professional’s help to examine and clean the evaporator coil. When all else fails, take a look at investing in air duct cleaning. This service cleans away hidden mold, no matter where it’s growing in your ductwork. 

The Furnace Smells Like Spoiled Eggs 

This is one of the most worrisome furnace smells due to the fact that it probably suggests a gas leak. The utility company adds a useful substance known as mercaptan to the natural gas supply to make leaks more easily detected. 

If you recognize a rotten egg smell around your furnace or coming from your air ducts, switch off the heater immediately. 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, in addition to 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 detect a sour smell that stings your nose while standing near64} the furnace, this could mean the heat exchanger is cracked. This essential component safely contains68} combustion fumes, like carbon monoxide, so a cracked heat exchanger could spew unsafe levels of CO gas into your home. 

Carbon monoxide poisoning could be lethal, so turn off your furnace right away if you recognize a sour odor. Then, contact an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is to blame. For your continued safety going forward, ensure you have working CO detectors on all floors of your home. 

The Furnace Smells Dusty 

When you fire up the furnace for the first time each fall, you should expect a dusty odor to appear for a little while. This is the smell of six months’ worth of dust burning away as the furnace wakes from its summer slumber. As long as the smell goes away within 24 hours, 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 could mean the flue is clogged, and now fumes are settling back into your home. The odor can reach through the entire house, jeopardizing your family’s health if you ignore it. So turn off the furnace and call a professional right away to request furnace 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 failing fan motor is another possibility. If you don’t tackle the problem, an electrical fire might start, or your furnace could end up with irreparable damage. Disable the heating system right away and call an HVAC technician for help identifying and repairing this unusual furnace smell. 

The Furnace Has an Oily Smell 

If you own an oil furnace, you could detect this stench whenever the oil filter becomes blocked up. Try replacing it to find out if that resolves the problem. If the smell persists for more than 24 hours after carrying out this step, it may suggest an oil leak. You’ll be better off with help from an HVAC specialist to address this problem. 

The Furnace Smells Like Sewer Odors 

Sewer gas smells very similar to rotting eggs, so first eliminate the likelihood of a natural gas leak. If that’s not the issue, your sewer lines could have an issue, for example a dry trap or sewer leak. Flush water down the drains, including the basement floor drain, to refresh dry 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 

When in doubt, contact an HVAC technician to examine and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we deliver thorough diagnostic services to identify the problem before the work begins. Then, we suggest 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 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.