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Weird Furnace Noises You May Hear—And What They Mean

woman-surprised-by-loud-noiseYou’re sitting in your house during a winter night, enjoying warmth coming from the furnace attached to the ductwork. Then suddenly, you hear the furnace make a noise different from the usual hum you hear from its blower fan. It could be a clang, a boom, a click, or a disquieting shrieking. Is something wrong?

Possibly. Just like a house settling, sometimes a furnace may make a slightly different noise, but it doesn’t return. But if the noise is persistent or causes the furnace to make a racket, there probably is a repair issue with it that will require heating repair in Salt Lake City, UT from professionals.

Below are a few of the more common warning noises you may hear from a furnace that’s got trouble.

Rattling and clanging

The sound of metal striking metal. And that’s often exactly what’s happening: there may be a loose part in the blower motor. For an older furnace that has a fan belt to turn the blower fan, these sounds might point toward a fan belt that has come loose. Loud, repeated clanging noises often mean a fan blade is bent and striking the housing of the air handler. On the simpler side, the rattling could just be the door to the HVAC cabinet wasn’t closed all the way.


Although this is a small sound, it may be warning you of a major problem—a cracked heat exchanger. If the furnace’s heat exchanger is cracked, it may allow toxic carbon monoxide to escape. If the clicking sound comes after the blower fan turns off, shut off the gas to the furnace and call for repairs. Clicking at other times can indicate dirt on the burners and failing electronic ignition systems.

Booming and Whooshing

These sounds can be alarming when they happen. You don’t want your furnace making noises that cause people to jump! These sounds often occur because of delayed ignition of the burners. When the burner finally comes on, they burn up the excess amount of gas in the combustion chamber all at once, creating the sound. You’ll want the burners and the ignition system checked on ASAP.


No, it’s not a banshee in your ductwork. What’s probably occurring here is the bearings of a motor in the furnace are wearing down. The bearings are designed to reduce friction in the motor, and if they wear all the way down, the motor will start to suffer damage. A technician can replace the bearings—and this is much less costly than replacing the motor!


This is a warning that you’ve probably got a motor that’s on the verge of burning out. Have help in as soon as you can get it.

We want to stress that you shouldn’t attempt to sleuth out the cause of the sound on your own. (Unless it’s something basic like a loose door.) It can be dangerous to tamper with a furnace if you aren’t trained in HVAC services, and even if you do locate the problem, you’re unlikely to be able to fix it properly. Call our technicians and we’ll be there—on time—to have the issue diagnosed and repaired.

Schedule your heating repairs with One Hour Heating & Air Conditioning. Always on Time, Or You Don’t Pay a Dime!

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