Unexpected and unpleasant odors coming from your furnace, like burning electrical, rotten eggs, or chemicals, should never be ignored as they could be signs of a potentially serious or even dangerous problem. While it’s quite common to notice a dusty burning smell the first time your furnace runs in the fall, if the odor persists, it should be checked out by a professional.
Dusty burning odor
As we mentioned above, a dusty burning smell when your furnace is started the first time each autumn is common and is usually nothing to worry about. Dust and dirt tend to accumulate during the summer while your unit is off, and the odor usually goes away after a few hours.
If the odor lingers, however, try changing your furnace filter. If that doesn’t eliminate the dusty burning smell within an hour or so, it’s time to call us for service. It could indicate that your furnace needs a proper cleaning, or it could have a more serious issue. Either way, it’s smart to play it safe and have us take a look.
Rotten egg odor
The most repulsive odor you may notice from your furnace is a rotten egg smell, and that nearly always indicates a gas leak. Natural gas suppliers typically add an odoring agent (usually Sulfur) to the gas to make leaks easier to detect without equipment. A natural gas leak is a hazardous situation, so if you notice a rotten egg smell near your furnace, immediately open windows to let in fresh air, evacuate your home, and call your local gas company right away – or 911, if you think an explosion may be likely – to report the leak.
Burning electrical odor
If you notice an odor like burning plastic or rubber, or like an overheated motor, it could indicate that the blower motor on your furnace isn’t spinning freely. The most common cause of this is worn bearings, and they’ll cause the motor to overheat, use too much voltage, and possibly even melt the wires that feed electricity to it. If you notice this smell throughout your house, use your thermostat to shut off the furnace immediately and then call us to come inspect your HVAC system.
A pungent chemical odor could be a sign that your furnace’s heat exchanger is cracked. This is another potentially dangerous problem because it can allow carbon monoxide (CO) gas to circulate through your home’s ductwork. CO gas inhalation is very dangerous and can be fatal – don’t risk your family’s safety! Carbon monoxide detectors should be located on each level of your home, especially near your furnace, because CO gas is odorless and colorless – without detectors, you wouldn’t know the gas was present until you were overcome by it. If you notice a chemical smell in the area around your furnace, turn the unit off immediately and call us to inspect your heating system as soon as possible.