Loud and unusual furnace noises can be disruptive and concerning, as they typically indicate problems with your heating system. Banging from your furnace can be an indicator of a few different system issues. Edwards Royal Comfort will explain the possible causes of this annoyance and how to stop a furnace from banging.

How to Stop Furnace from Banging

Before you can start working on how to stop a furnace from making a banging sound, you need to figure out what issue is behind the loud banging noise you hear. Below you’ll find furnace issues that can produce banging noise as a symptom, and we’ll explain how to stop furnaces from banging based on the problem at hand.

Clean Any Dirty Burners

If you hear a banging noise when your furnace turns on, this sound is typically caused by dirty burners inside the unit. Carbon and soot, as well as dirt and other debris, can build up on the furnace’s burners and restrict the ignition of gas inside the unit. Gas continues to build up inside the combustion chamber until it can be ignited. The bang that you hear is the sound of a larger volume of fuel finally igniting, creating a small explosion. This issue is called delayed ignition.

If you suspect delayed ignition is producing the banging noise you hear, you’ll need to clean your burners to stop the furnace from banging. 

If you’re a confident DIYer, you may feel comfortable performing this maintenance step on your own, which involves removing the burners individually. In older units, it may be necessary to remove the entire burner unit. The furnace’s burners are typically cleaned during a heating system tune up, but you can schedule service to have this task performed in between maintenance visits by your HVAC technician, too.

Replace Your Dirty Furnace Filter

Loud banging from the furnace, notably when a heating cycle ends, is usually the result of contracting metal panels on the equipment cabinet. Under normal operation, this should not happen. When the furnace filter is dirty, it creates a blockage that causes heated air to back up into the furnace and heat the metal furnace panels as well as your ducts. Heat causes the metal material to expand and push outward – when the cycle stops and the metal cools, it contracts and pops back into place, generating that loud banging sound that you hear indoors.

In this case, the best solution is simply to change the dirty air filter. Remember, filters need to be replaced regularly and it isn’t uncommon to change a filter more often over the winter as the system sees more use during these months. Check the filter monthly and change as needed to prevent future overheating and banging.

Clean Your Ducts

Just as a dirty filter can cause metal furnace panels to overheat and expand then contract when it cools, dirt inside your ducts can do the same to the sheet metal pieces that make up your home’s duct system. Deposits of dirt and debris hiding inside your ductwork can restrict air movement and hold heated air in certain areas, preventing it from circulating to your living areas. These ducts will overheat and their metal walls will expand outward. Once the heating cycle ends, the metal contracts, and the walls pop back into position, creating a loud bang. 

To stop the furnace from banging inside the ductwork, you might need to have your ducts cleaned. Duct cleaning is a job for an HVAC professional, as the interiors of your duct system are difficult to impossible to easily access on your own. A duct cleaning professional uses safe methods and professional tools to rid your ducts of dirt and debris while protecting your home from this mess, too.

Help for Furnace Banging Noises

If you cannot figure out how to stop your furnace from making banging noises, Edwards Royal Comfort can help! Our furnace technicians can diagnose the banging sounds from your heating system and put an end to them today. Contact us to schedule furnace repair services in your Indiana home.