What To Know When Your Furnace Is Making Odd Sounds

It's important that you take steps to ensure your furnace remains functional during the upcoming winter. That's why you want to be on the lookout for signs that the unit could need a professional to inspect or repair it. Here are some furnace sounds that should be a red flag that something is wrong and needs to be fixed.


A common reason for rattling with your HVAC system is due to loose ductwork. You could have an air handler creating enough vibration that it is rattling the ductwork attached to the unit, which is traveling through your home since the ductwork is made out of metal. These loose sections of ductwork may just need to be secured in order to prevent the annoying noise from happening.

Rattling can also happen due to loose parts within the air handler. There are fans that spin and belts that help turn moving parts, and any of them can be loose and cause a rattling sound. If the problem is within your furnace, it is worth having an HVAC inspector come and investigate the problem. Ratting is a sign that something is likely broken and needs to be replaced.


Loud banging is caused when your furnace is having a problem turning on. If the furnace cannot ignite when intended, there may be a lot of gas building up in the furnace while the unit struggles to turn on. Once ignition occurs, you'll then hear a loud bang from your furnace. Consider it a mini-explosion that has been contained to the furnace, which is not good for the unit. You'll need a professional to come and replace damaged parts or clean those that are dirty and preventing the furnace from turning on.


All air produced by your air handler needs to pass through the air filter. If the filter is clogged due to a lot of dust and debris, the air may try to squeeze through the smallest holes that it can find. This can cause a whistling sound that is very easy to fix. Try swapping out your air filter for a new one and see if that fixes the problem.


A squealing sound is likely due to metal rubbing against metal somewhere in the furnace. This problem may be as simple as applying more lubrication to moving parts so that there is not as much friction going on between them.

For more information, contact an HVAC repair professional.