Why Your Furnace Has a Strange Smell

As the weather cools down and you switch from cooling to heating your home, you might be worried about strange furnace smells filling the air. Learn what the most common furnace smells mean and how concerned you should be about each one. 

The Furnace Smells Musty 

Musty furnace odors generally indicate mold growth somewhere in the HVAC system. To avoid subjecting your family to allergy-inducing mold, handle this problem as soon as possible. 

A damp air filter can harbor mold, so eliminating the smell might be as easy as replacing the filter. If that doesn’t work, the AC evaporator coil mounted near the furnace could be the root of the problem. This component collects condensation, which could stimulate mold growth. You’ll need a professional’s help to check and clean the evaporator coil. When all else fails, consider scheduling air duct cleaning. This service cleans away hidden mold, no matter where it’s growing in your air ducts. 

The Furnace Smells Like Rotten Eggs 

This is one of the most concerning furnace smells since it most likely indicates a gas leak. The utility company adds a useful substance known as mercaptan to the natural gas supply to make leaks easier to notice. 

If you notice a rotten egg smell close to your furnace or coming from your vents, shut down the heater immediately. If you know where the main gas supply valve is placed, shut that off too. Then, get out of the house and dial 911, followed by 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 standing near64} the furnace, this could mean the heat exchanger is cracked. This important component contains68} combustion fumes, like carbon monoxide, so a crack could pump unsafe levels of CO gas into your home. 

Carbon monoxide poisoning can be deadly, so shut off your furnace right away if you detect 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, make sure you have working 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 should expect a dusty odor to show up for a few minutes. 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 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 could mean the flue is backed up, and now fumes are backdrafting into your home. The odor may permeate the entire house, jeopardizing your family’s health if you ignore it. So shut down the furnace and contact a professional right away to arrange for repair. 

The Furnace Smell Resembles Burning Plastic 

Overheating and melting electrical components are the most plausible reason for a burning plastic smell to come from your furnace. A failing fan motor is another possibility. If you don’t address the problem, an electrical fire could 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 might detect this stench if the oil filter becomes clogged. Try replacing it to see if that fixes the problem. If the smell lingers for more than a day after carrying out this step, it could indicate an oil leak. You’ll need help from an HVAC expert to fix this problem. 

The Furnace Reeks of Sewer Odors 

Sewer gas smells quite similar to rotten eggs, so first rule out the possibility of a natural gas leak. If that’s not the problem, your home’s sewer lines could have an issue, such as a dry trap or sewer leak. Try pouring water down all your drains, including the basement floor drain, to replenish dried-up sewer traps. If the smell persists, you should contact a sewer line repair company. 

Contact Midland Air Service Experts for Furnace Repair 

When in doubt, call an HVAC technician to assess and repair your furnace. At Midland Air Service Experts, we offer thorough diagnostic services to pinpoint the problem before the work begins. Then, we suggest the most viable, cost-effective repairs, as well as 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. For details about why your furnace smells bad or to request furnace repair near you, please contact your local Midland Air Service Experts office today.