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 strange noises. Some noises — like a few faint pops or clicks prior to the warm air beginning to blow — are normal and harmless. But others could impair the equipment or even jeopardize your health if you ignore them. Of all the furnace noises you might encounter, here are nine that are worthy of an immediate furnace repair.

Scraping Furnace Noise

If you hear a sound like metal scraping on metal, this could mean the blower wheel has come loose from the motor shaft, or the wheel or motor mount is broke. No matter what the exact problem, you should switch off your furnace if you notice 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 right away and begin heating your home. A loud boom at startup likely means the burners are dirty, which causes a delayed ignition. When the gas at last does ignite, you hear this terrifying furnace noise.

A small blast each time your furnace turns on could bust the heat exchanger, a pricey repair that might require you to switch out the entire furnace. Act before it gets to this point! Shut off your furnace if you hear a loud boom at startup, and don’t use it again until it has been repaired.

Squealing or Whining Sounds

A screaky or loud squealing furnace noise typically implies poor lubrication. Shaft bearings and other moving parts require lightweight oil to function smoothly. If the parts are not lubricated, components grate against each other and cause unnecessary wear and tear. Our recommendation is to have this situation remedied right away to protect against premature furnace failure.

Chirping Noise

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

However, if the chirping doesn’t subside, it could mean the pulley for the blower motor is crooked or the mounting plate is touching the blower wheel. This isn’t always a safety hazard, but the only way to eliminate the annoying furnace noise is to have a technician perform a repair.

Screeching Furnace

Screeching noises are definite indicators that the fan belt is deteriorating. If the fraying belt cracks, it could whip around inside the furnace, damaging other components and contributing to a much more expensive repair. Insulate yourself from this hassle by replacing the worn-out belt sooner rather than later.

Persistent Clicking.

Some furnaces give off a quick series of clicks when they flip on and off. This is completely normal. However, if the noise carries on longer than approximately 60 seconds, this could signal an electrical problem. To avoid risking a house fire, call a furnace repair professional to correct the problem immediately.

Thwapping Sounds

The blower motor should operate without problems when the furnace activates. If you discover a thwapping sound that rapidly picks up speed as the blower gets going, this could mean something is stuck in the fan, and the blades are striking it with each rotation. A simple repair should be all that's required to stop this bothersome furnace noise and prevent damaging the blower motor.

Rattling Furnace

A few different problems can cause your furnace to rattle. It might be as basic as a loose door cover, so verify that option first. If the rattling persists, the most probable culprit is a malfunctioning blower motor. Treat this as 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 loose, allowing conditioned air to leak. These aren’t critical matters, but if you have them fixed quickly, 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 unsure whether the furnace noises you hear match these descriptions? Maybe nothing’s wrong, but for your peace of mind, the best thing to do is to call a professional. At Service Experts Heating & Air Conditioning, we provide emergency furnace repair to get your unit 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 dissatisfied with our work anytime in the next 12 months, we’ll fix it! For more information or to arrange a furnace repair visit, please speak a Service Experts office near you.

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