Your Ductwork: Why You Are Hearing Loud Noises When the Heat Turns Off and On

13 October 2016
 Categories: , Blog

If you are hearing loud noises coming from your furnace and ductwork when the heat turns off and on, don't be alarmed. Banging noises can be loud, but this doesn't mean that you have a huge problem with your heating system. While you will want to get your system serviced by a professional HVAC company, the noises you are hearing probably aren't indicative of an expensive repair. Routine maintenance of your heating and cooling system can help keep the loud noises to a minimum.

The Filter Is Clogged

Air needs to be able to flow freely in your ductwork, and it can't when the filter is clogged. When the filter is blocked, this will cause air to back up in the ductwork. When the system turns off, you will hear a loud banging noise as the pressure inside the ductwork is released.

Your Ductwork Is Dirty

Just like a blocked air filter, if there are obstructions in your ductwork, the air won't flow readily. Once your ductwork is professionally cleaned, you should notice a significant decrease in the noises coming from your heating system.

The Dampers May Need to Be Adjusted

The ductwork expands and contracts depending on the temperature of air that is within the ductwork. There are dampers throughout the ductwork, and these dampers can be opened to help improve the airflow within. If you hear loud noises, try opening up a damper to see if this solves the problem. You may have to open more than one damper in order to fix the problem. If you still hear loud noises after that, then it's time to work with a professional.

Your Fan Is Dirty

There is a fan located inside your ductwork, and if it's dirty you can hear noises when your furnace shuts on and off. Your fan may be difficult to reach, but you can try cleaning out your fan with a vacuum if it is accessible to you. 

Your ductwork makes noises when the air can't flow freely through the system. Air gets backed up from dirty fans, clogged filters, and debris in the ductwork. When you don't want to try and fix the problem on your own, routine servicing from an HVAC professional should take care of the problem. While the noises don't usually indicate a serious problem, they can still be disturbing to those that live in the home. To keep your system running smoothly, get it serviced at least once a year.

Visit sites such as to find an HVAC company near you.