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Why Your Heater Smells Like It’s Burning

First time firing up your heater? Find out what odors are normal and when to get expert help.

November 12, 2021
As we approach the winter and temperatures begin to drop, many homeowners are getting ready to turn on their heaters for the season. But, when you change the temperature on your thermostat expecting it to warm up your house, the last thing you want to be met with is an unpleasant burning smell.
If you have found yourself in this situation, don’t panic! While some odors could be a sign of a potentially dangerous issue that requires calling an HVAC professional right away, other unwanted smells are common. Here, we’re breaking down what might be causing your heater to smell like it’s burning, and what you can do to safely handle each situation.

What’s causing a burning smell from your heater?

There are a few likely suspects that might be causing a suspicious odor to enter your home when you switch on your furnace or other heating unit. While you should always call in an HVAC professional to handle major issues with your system, in some situations, you might be able to do some troubleshooting on your own to get to the root cause of the burning smell.

Dust on the furnace

A burning smell when you first turn your heater on is most likely caused by dust buildup on your furnace. For homeowners who live in a region that often experiences changing seasons, like in the Mid-Atlantic, it’s likely that the furnace isn’t used all year round. Dust collects on your furnace during the months it remains untouched. When you turn it on for the first time after not using it for a while, this dust begins to burn off, oftentimes causing a burning plastic smell in the house.
What can you do?
Luckily, dust buildup on your furnace usually isn’t a cause for concern, because after the dust burns off the smell should go away. Inspect your unit and, without touching it, see if you notice dust buildup. If you suspect dust might be the cause of your issue, allow your unit to run as normal for about 10 minutes to see if the smell subsides or disappears. If the smell lingers or gets worse, turn your unit off and contact an HVAC professional for help. 

Debris trapped in the heating system

While your heating system wasn’t in use, it’s possible that some kind of object accidentally fell into your HVAC device or into the ductwork the system uses if you have central heating and cooling. If you have central heating with various vents throughout your home, see if you can pinpoint the burning smell to one specific room. If you’re successful, there might be something trapped inside your vent that’s causing the odor.
What can you do?
If you can find the room where the smell is coming from, try reaching the vent. If you can, open it or peer inside. You might be able to spot a toy, a part of the heating system, or another object trapped inside. Try safely removing the object from your vent and then wait to see if the burning smell from the heater continues. If you can’t safely remove it or the smell persists, call in an HVAC professional to assist.

Dirty furnace filters or air vents

Gas furnace maintenance is essential in helping you prevent a burning smell from emanating from your heater. If your furnace has dirty filters or the air vents in your system are clogged, the buildup could cause mold or mildew to grow inside either your heating system or ductwork. This can result in an unpleasant musty smell when you turn on your system.
What can you do?
If you’re detecting a musty scent coming from your furnace, turn your unit completely off. Then, have your filter cleaned or replaced inside your unit and try running it again. If a newly cleaned filter doesn’t eliminate the odor, call in an HVAC professional to inspect your unit and your ductwork.

Damaged electrical wiring

A burning electrical smell coming from your heater could indicate you have a serious electrical problem. General wear and tear over time or incorrect installation can damage your system’s electrical wiring. If your wiring is damaged, it could result in a cracked heat exchanger, the blower motor overheating, or a variety of other problems you’d probably rather avoid. All these problems are serious and need to be addressed immediately by a licensed HVAC professional only.
What can you do?
If you suspect an electrical problem might be making your heater smell like it’s burning, turn off your unit immediately and contact a licensed HVAC professional to fix the problem.
Need help with heater smells? Find an HVAC technician near you.

When you may need a furnace repair

Many of the possible odor problems we’ve already mentioned are quick fixes. But, there are situations in which you could be facing a full-on furnace repair. In any of these situations, if the burning smell doesn’t subside in about an hour after troubleshooting, a larger issue may be at play and you should call an HVAC professional to help as soon as possible.
A heater with a burning smell may have a significant electrical issue or an equally serious problem like structure damage to the unit or a malfunctioning part. If any of these are causing your unwanted odor, an HVAC technician may need to repair a part of your furnace or replace it entirely before you can safely heat your home again.

Can you avoid a burning smell from your heater?

The best way to avoid unwanted heater smells is to schedule regular maintenance on your unit with an HVAC professional. Furnace maintenance should happen at least once a year, sometimes twice for certain types of units. When a technician comes for a regular maintenance visit, they’ll be able to clean off your furnace, which will help prevent burning smells resulting from dust buildup, as well as inspect your unit for any kind of serious electrical issues. 
Plus, keeping up with regular maintenance you can do yourself, like changing your filters every three months, will help keep your unit running smoothly and keep your home free of unwanted smells. While regular maintenance isn’t a foolproof way of avoiding a burning smell from your heater, it’s the best thing you can do to avoid running into this problem every winter when you turn up the heat on your thermostat.
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