The season to be jolly is right around the corner, so you should pay attention to the proper operation of your heating system. Nine times out of ten, you will be able to tell when something’s wrong with your furnace, especially if it’s something obvious like a weird smell.
Some smells coming from your furnace are expected, and not all weird smells signal a malfunction or pose a risk for your safety. However, information is power, so keep reading to find out when you should stress and when you shouldn’t make a fuss because of your furnace’s smells.
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What is a typical burnt off smell?
Your furnace doesn’t actively heat all the time; when it doesn’t, the dirt and dust particles may collect inside your furnace and on the internal elements. Once you turn it on again, the dust will start burning, creating the light burning odor that shouldn’t linger for a long time.
However, if the smell lasts for more than an hour, you may have to try various fixes, like replacing the air filter and such. That’s why you should scroll down and find out when to worry about the smells coming from your furnace.
What causes the burning smell? How can you fix it?
As furnaces are complicated devices, several factors may cause problems, burning smell included. The more you read about it, the easier it will be for you to identify the cause and fix it.
Burning dust
It’s the burning smell that we’ve already talked about. Every time you turn on the furnace in the cold season, a burning smell will come from the furnace. When you’re not using the furnace for several months, it’s perfectly normal for the dust to collect inside the furnace, on burners, and heat exchanger.
The vents related to your heating system will typically send the smell throughout the whole household, and it’s nothing to worry about. The odor is supposed to disappear in a couple of minutes. If it doesn’t, the following information will shed some light on the possible causes.
Electrical burning
Typically, a reliable furnace should turn off automatically in case of overheating. When it doesn’t, your furnace’s safety feature could be damaged, which requires immediate fixing. When the overheating part doesn’t run properly, the risk of electrical fire is significant and puts you and your family at high risk,
Should you sense a burning electrical smell from the vents, the burning electrical components may be broken. Call the HVAC technician for future investigation and proper repair.
Clogged air filter
A clogged filter on the furnace will make the blower motor work a lot harder, which causes overheat and a burning smell. As the blower motor still tries to push the heated air through the clogged filter, it will eventually overheat and cause the burning smell.
The clogged filter makes dirt collect on the furnace in more massive amounts; the dirt will burn off and cause the burning smell the moment you turn the furnace on.
Smell of gunpowder
If the circuit board inside the furnace overheats, it will generate a smell similar to gunpowder. The same situation can happen with the overheated fan motor. Either way, you should turn off the furnace right away when you sense gunpowder odor. Once again, you should call the HVAC technician to look into and make the necessary repairs. Not running the furnace for a while won’t fix the problem, so don’t turn the furnace back until your HVAC technician addresses the issue.
Burning plastic
Sometimes, a smell of burnt plastic could come from your furnace, and it can be what it sounds: a foreign object somehow trapped inside the heating unit. A plastic bottle cap or a toy can get there.
The heat of the furnace is high enough to burn the plastic object, causing the burning smell. The fumes of burnt plastic are dangerous for your health, so turn off the furnace immediately and call the HVAC technician for fixing.
Are there other kinds of smells to worry about?
A burning smell isn’t the only type of odor coming from your furnace. Identifying the smell from the furnace provides ideas about the possible causes and fixes, if possible.
The smell of oil/smoke
It’s common for oil furnaces to generate smells resembling oil or smoke. If you’re using an oil furnace, you should change the oil filter to reduce the risk of overheating. If that doesn’t solve the problem, it’s better that you call the HVAC professional for further investigation and repair.
Until the technician comes, you should turn off the furnace and restrain from turning it back on until repairs are made. The risk for your unit to catch on fire is high if you keep on running it.
Metallic & electrical burning smell
Unless you have a running nose, you should use it to identify the source of the smell. Worn bearing, overheated motor, or wiring problems could cause the metallic and electrical smell.
Electrical wiring inside the furnace may cause a specific acrid, metallic smell as it starts burning. Unshielded or damaged wiring may cause electrical shorts as they cause sparks and melt the wiring insulators. Furnace elements of your furnace made entirely of metal can also generate the weird metallic smell as they’re overheating. No matter the cause for the metallic smell, you should turn off the furnace and wait for the HVAC professional. Should you keep on running the furnace, you may cause more electrical damage to the furnace and even pose a risk of electrical shock.
Rotten eggs/sulfur
Propane and natural gas are odorless in the natural states, so they’re almost impossible to detect. It\s the main reason propane and natural gas suppliers add methyl mercaptan (it’s an organic compound) to the gases before distribution. Moreover, methyl mercaptan is colorless, but it can generate a powerful smell resembling rotten eggs or cabbage.
Should you notice rotten eggs/sulfur smell when running your furnace, you should leave your house asap and call the gas company too. Gas leaks pose a high risk for your safety, and only professionals are trained for fixing any problems.
From the moment you sense a strong whiff of rotten eggs after turning on your gas furnace, shut it down and go outside the house. The gas company should also shut off your house’s gas supply and identify the source of the gas leak.
If the gas leaks come from your furnace, you need to call the HVAC professionals for proper fixing.
Musty/moldy/locker room odor
some mold or bacteria buildup in the filter or the home could cause unpleasant smells. Take a look at the filter and replace it if it’s beyond cleaning.
Some organic growth on the cooling coil (evaporator) or in the ductwork could cause the smells. No matter the cause, you won’t be able to clean it on your own. Call a duct cleaning professional or an HVAC contractor for professional cleaning.
