Why Your Furnace Has a Strange Smell

As the weather gets colder and you swap from cooling to heating your home, you might be worried about unusual furnace smells floating in the air. Find out what the most common furnace smells could suggest and how proactive you should be about them.

The Furnace Smells Musty

Musty furnace odors almost always indicate mold growth somewhere in the HVAC system. To avoid exposing your family to these microorganisms, tackle this problem right away.

A damp air filter can harbor mold, so wiping out the smell could be as easy as swapping out filter. If that fails to remove the smell, the AC evaporator coil placed near the furnace could be to blame. This component gathers condensation, which will sometimes trigger mold growth. You'll be better off with a professional’s help to inspect and clean the evaporator coil. When this still doesn't help, start thinking about scheduling air duct cleaning. This service cleans away hidden mold, no matter where it's hiding in your ventilation.

The Furnace Smells Like Spoiled Eggs

This is one of the most nerve-wracking furnace smells because it probably indicates a gas leak. The utility company includes a special substance known as mercaptan to the natural gas supply to make leaks easier to notice.

If you notice a rotten egg smell around your furnace or coming from your ductwork, shut down the heater immediately. If you can find where the main gas supply valve is located, shut that off also. Then, leave the house and contact 911, in addition to your gas company. Don’t enter the house until a professional can verify it’s safe.

The Furnace Has a Sour Stench

If you notice a sour smell that stings your nose while close to the furnace, this might mean the heat exchanger cracked open. This important component houses combustion fumes, such as carbon monoxide, so a cracked heat exchanger might pump unsafe levels of CO gas into your home.

Carbon monoxide poisoning has the potential to be fatal, so shut off your furnace as soon as possible if you recognize 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, make sure you have functional CO detectors on every 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 show up for a little while. This is the smell of six months’ worth of dust burning away as the furnace wakes up. As long as the smell disperses within 24 hours, 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 up and out of your home. A smoky smell could mean the flue is blocked, and now fumes are flowing back into your home. The odor can reach through the entire house, risking your family’s health if you ignore it. So switch off the furnace and get in touch with a professional as soon as you can to schedule a repair.

The Furnace Smells Like It's Burning Plastic

Overheating and melting electrical components are the most common reason for a burning plastic smell to appear. A failing fan motor is also possible. If you don’t correct the problem, an electrical fire could start, or your furnace could end up with irreparable damage. Turn off the heating system right away and call an HVAC technician for help diagnosing and repairing this unusual furnace smell.

The Furnace Has an Oily Smell

If you have an oil furnace, you may notice this odor if the oil filter becomes clogged. Try replacing it to find out if that addresses the problem. If the smell remains for more than 24 hours after taking care of this step, it might imply an oil leak. You’ll need help from an HVAC expert to fix this problem.

The Furnace Reeks of Sewer Odors

Sewer gas smells very similar to spoiled eggs, so first determine the potential for a natural gas leak. If that’s not the issue, the sewer lines might have an issue, for example a dry trap or sewer leak. Pour water down all your drains, including the basement floor drain, to refresh dry sewer traps. If the smell sticks around, you’ll need to contact a sewer line repair company.

Contact Comfort Masters Service Experts for Furnace Repair

When in doubt, contact an HVAC technician to assess and repair your furnace. At Comfort Masters Service Experts, we deliver complete diagnostic services to pinpoint 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 handle just about any heating malfunction, 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 Comfort Masters Service Experts office today.

chat now widget box