9 Common Furnace Noises and What They Mean

Over time, when you fire up your furnace, you know how it’s supposed to sound. So it will likely catch your attention if the unit starts making odd noises. Some noises — like a few small pops or clicks ahead of the warm air beginning to blow — are perfectly harmless. But others could ruin the equipment or even endanger your health if you dismiss them. Among the possible noises that you may hear, here are nine that justify an immediate furnace repair.

Scraping Furnace Noise

When you hear a sound like metal rubbing on metal, this could mean 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 turn off your furnace if you discover a scraping sound and call a professional for an urgent repair.

Loud Boom at Startup

When your furnace starts up, the burners should ignite immediately and get started heating your home. A loud boom at startup potentially means the burners are dirty, resulting in delayed ignition. When the gas at last does ignite, you hear this scary furnace noise.

A small boom each time your furnace turns on could crack the heat exchanger, an expensive repair that may force you to switch out the entire furnace. Don’t let it come to this! Shut off your furnace if you hear a loud boom at startup, and do not activate it again until it has been repaired.

Squealing or Whining Sounds

A high-pitched squealing furnace noise typically signifies poor lubrication. Multiple parts of a furnace need lightweight oil to operate smoothly. If these parts are dry, components grate against each other and cause unwanted 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 caught in your furnace definitely warrants investigation. If you perceive chirping during the first furnace cycle of the season, it could simply 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 doesn’t subside, it could imply the pulley for the blower motor is crooked or the mounting plate is contacting the blower wheel. This isn’t necessarily a safety threat, but the only choice to get rid of the annoying furnace noise is to have a technician perform a repair.

Screeching Furnace

Screeching noises are an unmistakable warning sign that the fan belt is failing. If the fraying belt breaks, it could create all kinds of issues inside the furnace, harming other components and contributing to a much more expensive repair. Insulate yourself from this hassle by exchanging the worn-out belt sooner rather than later.

Continual Clicking.

Some furnaces give off a rapid series of clicks when they flip on and off. There is nothing unusual about that. That said, if the noise carries on longer than a minute or so, this could suggest an electrical issue. Don't risk your home catching fire by a faulty electrical situation; call a furnace repair professional to fix the problem promptly.

Thwapping Sounds

The blower motor should operate without problems when the furnace activates. If you hear a thwapping sound that quickly picks up speed as the blower gets going, this could mean something is snagged in the fan, and the blades are hitting it with each rotation. A straightforward repair should be all you need to eliminate this pestering furnace noise and protect against damaging the blower motor.

Rattling Furnace

A rattling furnace can be caused by multiple issues. It might be as simple as a loose door cover, so check this first. If the rattling continues, the most likely culprit is a failing blower motor. Consider this a warning sign to have your furnace repaired before it is an urgent situation.

Whistling or Vibrating

Noises such as a teapot whistle or the hum of a vibrating item are signals of a problem with the air intake vent. If the whistling or vibrating comes from a vent, your ductwork is likely loose, allowing conditioned air to leak. These aren’t emergency matters, but if you fix it soon, you’ll pay less on your heating and cooling bills long term.

Schedule Furnace Repair with Service Experts Heating & Air Conditioning

Are you uncertain whether the furnace noises you hear align with 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 system functioning properly as fast as possible. Be confident knowing that we stand behind our work with a one-year, 100% satisfaction guarantee. If you’re disappointed with our work anytime in the next 12 months, we’ll set things right! For additional information or to arrange a furnace repair visit, please speak a Service Experts office near you.

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