9 Common Furnace Noises and What They Mean

If you've had your furnace for several winter seasons, you know how it’s supposed to sound. So it will likely catch your attention if the equipment starts making unfamiliar sounds. Some noises — like a couple of faint pops or clicks ahead of the warm air beginning to blow — are completely harmless. But others could damage the equipment or even threaten your health if you ignore them. Of all the furnace noises you might encounter, here are nine that warrant an immediate furnace repair.

Scraping Furnace Noise

When you hear a sound like metal rubbing on metal, this could suggest the blower wheel has come loose from the motor shaft, or the wheel or motor mount has broken. No matter what the specific problem, you should shut off your furnace if you notice a scraping sound and call a professional for an critical repair.

Loud Boom at Startup

When you start your furnace, the burners should ignite right away and begin heating your home. A loud boom at startup potentially means the burners are dirty, causing a delayed ignition. When the gas finally does ignite, you hear this terrifying furnace noise.

A small explosion each time your furnace turns on could break the heat exchanger, an expensive repair that may force you to switch out the entire furnace. Act before it gets to this point! Turn off your furnace if you hear a loud boom at startup, and avoid using it again until it has been repaired.

Squealing or Whining Sounds

A high-pitched squealing furnace noise typically indicates poor lubrication. Like many mechanical equipment with moving parts inside, they need lightweight oil to operate smoothly. If the parts are not lubricated, components rub against each other and cause unnecessary wear and tear. Our recommendation is to have this problem remedied right away to avoid premature furnace failure.

Chirping Noise

The sound of a bird trapped in your furnace certainly warrants investigation. If you notice chirping during the first furnace cycle of the season, it could just mean your furnace is warming up after an extended period of no use. In cases like this, the sound should go away after a few cycles.

However, if the chirping continues, it could imply the pulley for the blower motor is crooked or the mounting plate is contacting the blower wheel. This isn’t always a safety risk, but the only option to get rid of the pesky furnace noise is to have a technician conduct a repair.

Screeching Furnace

Screeching noises are clear and certain signs that the fan belt is deteriorating. If the fraying belt cracks, it could create all kinds of issues inside the furnace, damaging other components and resulting in a much more expensive repair. You can protect yourself from this unexpected expense by exchanging the worn-out belt sooner rather than later.

Repeated Clicking.

Some furnaces give off a quick series of clicks when they switch on and off. This is completely normal. That said, if the noise persists longer than approximately 60 seconds, this could indicate an electrical complication. Don't risk an electrical fire! Simply call a furnace repair professional to correct the problem promptly.

Thwapping Sounds

The blower motor should perform properly when the furnace activates. If you notice a thwapping sound that quickly picks up speed as the blower gets going, this could mean something is caught in the fan, and the blades are striking it with each rotation. A simple repair should be all you need to eliminate this pestering furnace noise and reduce the risk of damaging the blower motor.

Rattling Furnace

There are several possible reasons for your furnace to produce a rattling sound. It might be as simple as a loose door cover, so verify that option first. If the rattling continues, the most likely root cause is a failing blower motor. Consider this a warning sign to have your furnace repaired before it entirely fails.

Whistling or Vibrating

When these noises come from the furnace, it could mean the air intake vent is dislodged. If the whistling or vibrating comes from a vent, your ductwork is likely detached, allowing conditioned air to escape. These aren’t critical matters, but if you have them fixed quickly, you’ll pay less on your heating and cooling bills long term.

Schedule Furnace Repair with Service Experts Heating & Air Conditioning

Are you unsure whether the furnace noises you hear correspond to these descriptions? It might be nothing, but the only way to know for sure is to call a professional. At Service Experts Heating & Air Conditioning, we provide emergency furnace repair to get your system performing properly as soon as possible. Be confident knowing that we stand behind our work with a one-year, 100% satisfaction guarantee. If you’re dissatisfied with our work anytime in the next 12 months, we’ll get it corrected! For additional information or to arrange a furnace repair visit, please speak a Service Experts office near you.

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