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 unit starts making weird sounds. Some noises — like a couple of minor pops or clicks ahead of the warm air beginning to blow — are normal and harmless. But others could impair the equipment or even jeopardize your health if you neglect them. While there are many more furnace noises to consider, here are nine that justify an immediate furnace repair.

Scraping Furnace Noise

The moment you hear a sound like metal scraping on metal, this could indicate the blower wheel is becoming detached from the motor shaft, or the wheel or motor mount has broken. Regardless of the precise problem, you should power down your furnace if you discover a scraping sound and call a professional for an urgent repair.

Loud Boom at Startup

When you fire up your furnace, the burners should ignite without delay and get started heating your home. A loud boom at startup potentially means the burners are dirty, which causes a delayed ignition. When the gas at last does ignite, you hear this frightening furnace noise.

A small explosion each time your furnace turns on could crack the heat exchanger, a pricey repair that may necessitate you to replace the entire furnace. Don’t let it come to this! 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 squealing furnace noise typically indicates poor lubrication. Multiple parts of a furnace need lightweight oil to run smoothly. Without this, components grind against each other and cause needless wear and tear. Our recommendation is to have this issue remedied right away to avoid premature furnace failure.

Chirping Noise

The sound of a bird lodged in your furnace absolutely warrants investigation. If you notice chirping coming from the furnace upon the first activation of the season, it could simply mean your furnace is warming up after months of no use. In cases like this, the sound should dissipate after a few cycles.

However, if the chirping does not end, it could indicate the pulley for the blower motor is out of alignment or the mounting plate is touching the blower wheel. This isn’t necessarily a safety threat, but the only way to eliminate the irritating furnace noise is to have a technician conduct a repair.

Screeching Furnace

Screeching noises are definite indicators 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.

Persistent Clicking.

Some furnaces give off a fast series of clicks when they flip on and off. This is common and no reason to be concerned. However, if the noise carries on longer than approximately 60 seconds, this could indicate an electrical problem. Don't risk an electrical fire! Simply call a furnace repair professional to solve the problem promptly.

Thwapping Sounds

The blower motor should perform smoothly when the furnace activates. If you discover a thwapping sound that rapidly picks up speed as the blower gets going, this is a strong indication that something is caught in the fan, and the blades are striking it with each rotation. A simple repair should be all it takes to get rid of this annoying 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 start there. If the rattling continues, the most plausible culprit is a declining blower motor. Take this as a warning sign to have your furnace repaired before it breaks down completely.

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 loose, allowing conditioned air to escape. These aren’t critical matters, but if you address it promptly, you’ll save money on your heating and cooling bills in the long run.

Schedule Furnace Repair with Service Experts Heating & Air Conditioning

Are you uncertain whether the furnace noises you hear align with these descriptions? Perhaps nothing is wrong, but the only way to know for sure is to call a professional. At Service Experts Heating & Air Conditioning, we offer emergency furnace repair to get your system back up and running as fast as possible. Feel safe knowing that we stand behind our work with a one-year, 100% satisfaction guarantee. If you’re unhappy with our work anytime in the next 12 months, we’ll set things right! For more information or to arrange a furnace repair visit, please speak a Service Experts office near you.

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