Why Your Furnace Has a Strange Smell

As the weather gets colder and you switch from cooling to heating your home, some homeowners are worried about unusual furnace smells filling the air. Find out what the most common furnace smells mean and how worried you should be about them.

The Furnace Smells Musty

Musty furnace odors almost always imply mold growth someplace in the HVAC system. To avoid subjecting your family to mold and mildew spores, tackle this problem as quickly as possible.

A wet air filter can encourage mold, so wiping out the smell might be as straightforward as getting a new filter. If that doesn’t work, the AC evaporator coil mounted near the furnace may be the root of the problem. This component accumulates condensation, which can trigger mold growth. You'll be better off with a professional’s help to examine and clean the evaporator coil. When all else fails, consider scheduling air duct cleaning. This service removes hidden mold, no matter where it’s growing in your ventilation.

The Furnace Smells Like Rotting Eggs

This is one of the most worrisome furnace smells because it probably suggests a gas leak. The utility company adds a special 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 vents, shut down the heater immediately. If you can find where the main gas supply valve is placed, shut that off as well. Then, get out of the house and call 911, followed by your gas company. Don’t reenter the house until a professional can verify it’s safe.

The Furnace Has a Sour Stench

If you discover a sour smell that stings your nose while standing near the furnace, this could mean the heat exchanger cracked open. This essential component safely contains combustion fumes, including carbon monoxide, so a crack might pump unsafe levels of CO gas into your home.

Carbon monoxide poisoning could be lethal, so switch off your furnace right away if you notice a sour odor. Then, call 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, ensure you have functional CO detectors on all floors of your home.

The Furnace Smells Dusty

When you turn on the furnace for the first time each fall, you probably expect a dusty odor to show up for a brief moment. 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 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 safely out of your home. A smoky smell could mean the flue is backed up, and now fumes are backdrafting into your home. The odor might eventually reach the entire house, risking your family’s health if you ignore it. So shut down the furnace and call a professional straightaway to arrange for 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 faulty fan motor is another possibility. If you don’t tackle the problem, an electrical fire might start, or your furnace could suffer from irreparable damage. Shut off the heating system right away and contact an HVAC technician for help identifying and repairing this unpleasant furnace smell.

The Furnace Has an Oily Smell

If you have an oil furnace, you might detect this odor whenever the oil filter becomes clogged. Try replacing it to determine if that addresses the problem. If the smell persists for more than 24 hours after completing this step, it could suggest an oil leak. You'll be better off with help from an HVAC professional to fix this problem.

The Furnace Reeks of Sewer Odors

Sewer gas smells pretty similar to rotten eggs, so first rule out the possibility of a natural gas leak. If that’s not the source, your sewer lines might have an issue, for example a dry trap or sewer leak. Flush water down all your drains, including the basement floor drain, to replenish dry sewer traps. If the smell lingers, you’ll need to contact a sewer line repair company.

Contact Bryant Heating & Cooling Service Experts for Furnace Repair

When in doubt, contact an HVAC technician to check and repair your furnace. At Bryant Heating & Cooling Service Experts, we deliver comprehensive diagnostic services to determine the problem before the work begins. Then, we suggest the most viable, cost-effective repairs, alongside an up-front estimate for each 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 ask questions about why your furnace smells bad or to request furnace repair near you, please contact your local Bryant Heating & Cooling Service Experts office today.

chat now widget box