Abnormal Furnace Sounds And What To Do If You Hear Them

Posted on: 31 August 2018


Heating your home is important. It is necessary to keep your family warm during the cooler seasons, but it is also essential for maintaining a healthy air quality in the home. Unfortunately, years of use and improper maintenance may all cause your furnace distress. In some instances, you will notice signs of distress because the furnace will start making unusual noises when it first comes on or while it is heating. This guide will help you learn the sounds of distress and how to restore your furnace back to a functional state.


Many metal components work together in your furnace to heat and move heated air into the home. Over time, these components will experience stress and pressure, causing them to contact one another, resulting in this scraping sound.

In most cases, this scraping will stem from a problem in your blower wheel. The piece may be loose or broken, which are both issues that can be easily repaired by tightening or replacing the blower wheel.

The motor mount may have broken, which would cause the blower component to shake, scraping on other parts of your furnace. This would require a complete replacement of the motor mount to ensure your furnace will heat the home properly.


All systems will make some noise when they are running. However, a loud whirring sound while the furnace is heating is a sure sign of distress.

Technicians will want to disconnect the power running to your furnace before inspecting the interior for issues. This whirring noise may be caused by a few different problems including a broken or loose belt or a malfunctioning blower motor.

Replacing the belt is a simple fix, and your technician can order a new blower motor if necessary.

On the other hand, the whirring may be a simple issue stemming from a lack of lubrication. Without lubrication, the shaft bearings will create a loud whirring sound due to the dry contact between them. Lubricating the bearings with oil will usually solve this problem.


A loud banging noise can be frightening, but it is actually very common when you first start up your furnace.

If your ignitor or furnace burner is dirty, covered in dust and dirt, the ignitor will create the bang when the furnace is first started up for the season. If the banging continues, the noise may be the expanding and contracting of the air ducts as the heat moves through your system.

In both of these cases, the banging will not last, so there should not be any cause for concern. If you are still hearing the banging after a few hours, have the furnace evaluated by heating technicians. For more information, contact your local heating and air conditioning contractor.