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Why Is My Gas Furnace Making Noise?

Worried about furnace noise?

Book a furnace inspection today!


Has your gas furnace been making strange noises lately? Maybe you’re hearing a loud bang when it starts up or an irritating screech while it runs.

Nearly all mechanical equipment makes some kind of noise, especially when starting up or shutting down, and a little bit of furnace noise is likely nothing to worry about. However, certain noises can indicate a problem. If your furnace is making sounds you’ve never heard before, or if the level of noise is high enough to affect your daily life, there could be something wrong. Keep reading to learn about some of the most common noises gas furnaces make and what they mean.

Grinding or Scraping 

If your furnace is making a grinding noise, the blower wheel may be loose or broken and bumping up against its housing. It’s also possible that a piece of hardware, such as a bolt, has broken off and lodged itself in the blower fan or motor. Both of these issues can cause serious damage to your furnace, so it’s important to shut the system off and call an HVAC technician for help if your furnace starts to make metallic grinding noises. 

Loud Rumbling 

Soot and dirt build up on your furnace burner during normal operation, which can block airflow and cause a loud rumbling noise. Regular cleaning will prevent this from happening, but if your furnace is making a loud rumbling noise and you’ve been slacking on furnace maintenance, you may need to call an HVAC repair contractor to inspect and clean the burner.   

High-Pitched Screeching 

A furnace that’s making high-pitched noises is irritating, but the good news is that these kinds of noises are not usually a cause for major concern. A high-pitched whistle could point to a low return airflow issue and indicate that your furnace is increasing air pressure in order to make up for it. If the noise sounds more like a screech, the bearings in your blower motor might be dry, or your fan belt could be loose. While these issues aren’t usually too worrisome, you’ll still want to have your furnace looked at as soon as possible to rule out other possibilities and resolve the problem so that you can go back to enjoying nice, quiet operation. 

Thumping & Banging 

A furnace that’s making banging noises, especially right when the system turns on, needs immediate attention. Loud thumping and banging noises can be caused by a number of serious issues, including an unbalanced blower motor or wheel, gas build-ups causing a delayed ignition, and air ducts that are expanding and contracting. Ignition issues and gas build-ups can be dangerous, so it’s important to turn your furnace off and schedule an immediate inspection if you suspect one of these issues.

Get the Furnace Help You Need Fast  

Furnace noise can drive you crazy, and it can also indicate a serious problem. To avoid unrepairable damage, call on the pros at Kearney HVAC as soon as you start hearing strange noises coming from your furnace or vents. Our expert technicians can inspect your furnace or boiler, find out what’s causing the noise, and provide a solution. We offer comprehensive heating services, including: 

With many years of experience serving homeowners in the North Shore of Massachusetts and the Seacoast Region of New Hampshire, from Sailsbury and Gloucester to Hampton and Portsmouth, Kearney HVAC is the company to call when you need reliable heating service. 

Worried about strange furnace sounds? Kearney HVAC can find out what’s causing that loud bang or blood-curdling screech and make it stop. Call 978-388-0845or get in touch here to schedule an HVAC service call today.