What Does it mean if my furnace has a burning smell?
This is a question often asked during the fall when homeowners are first turning on their furnaces to knock off that first chill in the air. When a furnace is turned on for the first time in a heating season, it may emit a burning smell, which is normally due to the accumulation of dust on its components during periods of inactivity. Over the off-season, dust settles on the heat exchanger, burners, and other internal parts of the furnace. When the furnace starts up again, the accumulated dust is heated, and the particles burn off. This is a normal and temporary occurrence, and the smell should dissipate after a short period. However, it’s essential to distinguish between this initial burning smell and persistent or unusual odors, as the latter may indicate more significant issues, such as a blocked vent or a malfunctioning component, which should be promptly addressed by a professional technician.
DIFFERENT TYPES OF FURNACE SMELLS & THEIR POTENTIAL CAUSES
BURNING SMELL CAUSED BY DUST
Heaters have sat dormant for months over the spring and summer. This off-season causes a buildup of lots of dust in the unit – covering the inside, including the heat exchanger and burners. When your furnace turns on, this dust gets burnt off in the process. If your burning smell is caused by dust, it will go away within a few hours. If it does persist, make sure to check that the air filter is clean. If it is not, change the filter and give it another hour or so before checking back in on the odor.
OIL SMELL COULD BE CAUSED BY DIRTY FILTER FURNACE
Having a dirty filter can lead to some interesting smells, even an odor similar to oil. Make sure to check your filter before turning on your furnace for the first time.
READ MORE: How often to Change Furnace Filter
MUSTY SMELL CAUSED BY DUST OR MOLD IN AIR DUCTS
Air recirculates in your home multiple times per day. If there is dust or mold in the air ducts or mold in any part of the furnace, you may smell a musty odor. If you smell a musty smell, it is best to have a professional come check out your system and air ducts to make sure there is no mold present. They should also clean out the furnace if dust is found to be the underlying cause of the smell.
If mold is present in your air ducts, you will need professional mold remediation. If there is just a musty smell, this can be solved and mold and bacteria prevented by getting an anti-microbial spray, which is part of many duct cleaning processes. If mold is present in the heating unit, call an HVAC service expert. If mold has completely overtaken the unit, replacement may be necessary.
Learn More About Air Duct Cleaning
PLASTIC SMELL
There are a couple main causes of a plastic smell coming from a furnace. The first is a foreign object in ductwork. This could be a child’s toy or a dog’s stuffed animal that you didn’t know made it into a vent. Pull off your vent covers and use a flashlight to see if any objects are visible.
The second root cause of a plastic smell from a furnace is an overheated motor or internal piece of the furnace that has overheated and burned. People sometimes describe this smell as “burning electrical parts” or even a gunpowder smell as well. If this is the cause of your smell, it needs to be fixed by a furnace repair professional.
WHAT TO DO WHEN YOU SMELL BURNING FROM YOUR FURNACE
If you smell a burnt odor coming from your furnace, make sure to keep a close watch on it for 2-3 hours. Opening your windows before you turn on the unit for the first time will help to alleviate some of the odor also. Follow the steps included above, including checking the filter and vents depending on the type of smell. If the smell persists, you need to turn off the unit immediately and call a professional HVAC company to inspect the system and diagnose the problem. Frequently smelling gas could be a sign of a dangerous leak and needs to be remedied immediately.
