My Furnace is Making Strange Noises!

“Come home to a real fire” — an advertising slogan from a while back. This simple message is really about keeping where you live warm and cozy. In reality, this is about having a well functioning and safe furnace that provides you and your family with reliable heating in your home.

For most people, the safety of their home is paramount. Part of this is making sure that the furnace is properly maintained and repaired when needed. 

What is sometimes more alarming than a furnace that has broken down is a furnace that works but has unexplained problems. Below is a guide to the main types of strange noises that a furnace can make, what they mean, and how to fix them.

Thumping or Scraping

Trying to describe noises is always a bit tricky, but if you hear a loud thumping noise or something that sounds like metal rubbing against metal, odds are it is a problem with the blower wheel in the furnace. 

The blower wheel pushes the hot air out of the furnace and through the house. If it is making a strange noise, it could be out of balance, there could be a problem with the motor itself that needs replacing, or the blower belt could have come loose from the blower motor.


A low rumbling noise could indicate a problem with the burner. The burner is the unit where the air and fuel mix to create heat, and any problem here seriously affects the furnace’s ability to function at all. 

This problem can be caused by a number of things, the most common being faulty valves or a build up of dirt. This can be quite serious, and the furnace should be switched off until the problem is addressed.


A squealing or squeaking noise that is usually fairly high pitched can mean a couple of things. It is sometimes a sign that the bearings of the blower motor are wearing out, or possibly a loose blower belt. Both of these can indicate that the blower motor needs to be replaced.


Sometimes a furnace will make a rattling noise. A blower motor will have weights on it to balance it properly. If these weights become misaligned, they’ll make a rattling noise. They will need to be re-adjusted.


Images via Flickr by kevingessner

Any problem with a furnace — or with any part of it such as a blower motor or wheel — should be inspected and fixed by a professional technician who is HVAC trained

There are a number reasons for why you should have it fixed, and the most important reason is safety. A furnace that doesn’t function properly is inherently unsafe. It poses risks to you and your family, including the possibility of carbon monoxide poisoning. 

Having a furnace repaired properly is a long-term investment. It should ensure the safety and well being of your home and give you peace of mind, especially during those long winter nights when a cozy home is so important.