Why Your Furnace Has a Strange Smell

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

The Furnace Smells Musty

Musty furnace odors usually indicate mold growth somewhere in the HVAC system. To avoid subjecting your family to mold and mildew spores, tackle this problem as quickly as possible.

A clogged air filter can lead to mold, so wiping out the smell might be as simple as replacing the filter. If that doesn’t work, the AC evaporator coil fastened near the furnace could be the culprit. This component collects condensation, which could stimulate mold growth. You'll be better off with a professional’s help to check and clean the evaporator coil. When the problem still won't go away, take a look at requesting air duct cleaning. This service removes hidden mold, regardless of where it’s growing in your ductwork.

The Furnace Smells Like Rotten Eggs

This is one of the most worrisome furnace smells because it probably indicates a gas leak. The utility company adds a particular substance known as mercaptan to the natural gas supply to make leaks more easily detected.

If you detect a rotten egg smell close to your furnace or coming from your ductwork, shut off the heater straightaway. If you remember where the main gas supply valve is, shut that off as well. Then, leave the house and dial 911, as well as your gas company. Don’t go back in the house until a professional tells you it’s safe.

The Furnace Has a Sour Stench

If you discover a sour smell that stings your nose while standing close to the furnace, this may mean the heat exchanger has cracked. This vital component contains combustion fumes, such as carbon monoxide, so cracks could spew unsafe levels of CO gas into your home.

Carbon monoxide poisoning can be lethal, so switch off your furnace as soon as possible if you detect a sour odor. Then, contact an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is responsible. For your family's safety going forward, ensure you have working CO detectors on all floors 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 show up for a little while. 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 24 hours, you shouldn'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 blocked, and now fumes are flowing back into your home. The odor may permeate the entire house, risking your family’s health if you neglect it. So turn off the furnace and contact a professional right away to schedule a repair.

The Furnace Smells Like It's Burning Plastic

Overheating and melted electrical components are the most common reason for a burning plastic smell to make an appearance. A malfunctioning fan motor is also possible. If you don’t tackle the problem, an electrical fire could start, or your furnace could suffer from irreparable damage. Disable the heating system as soon as possible and call an HVAC technician for help troubleshooting and repairing this unpleasant furnace smell.

The Furnace Has an Oily Smell

If you own an oil furnace, you might pick up on this odor if the oil filter becomes blocked up. Try replacing it to see if that fixes the problem. If the smell lingers for more than a day after taking care of this step, it might indicate an oil leak. You’ll need help from an HVAC professional to address this problem.

The Furnace Smell Resembles Sewer Odors

Sewer gas smells pretty similar to rotten eggs, so first eliminate the potential for a natural gas leak. If that’s not the source, the sewer lines may have an issue, such as a dry trap or sewer leak. Pour water down your own drains, including the basement floor drain, to refresh dried-up sewer traps. If the smell sticks around, you’ll need to contact a sewer line repair company.

Contact Coastal Service Experts for Furnace Repair

When in doubt, get in touch with an HVAC technician to assess and repair your furnace. At Coastal Service Experts, we perform comprehensive diagnostic services to identify the problem before we figure out the best solution. Then, we recommend the most viable, cost-effective repairs, alongside an up-front estimate for every option. Our ACE-certified technicians can manage just about any heating malfunction, 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 Coastal Service Experts office today.

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