Why is My Furnace Making Noise?

why my furnace making noise
Dec 2018 03

It is common for a furnace to make noise, but sometimes we hear noises that are out of the ordinary. Sometimes this is simply your forced air furnace being louder than usual when running, or it could be odd noises that have you concerned. Depending on the noise you’re hearing, it could be a number of problems that deserve your attention, or the attention of an HVAC professional. To help quiet your noisy furnace, let's first take a look at some of the common noises you might be hearing.


A high-pitched squealing noise could be a serious problem and deserves immediate attention. This could be a problem with your blower belt, either coming loose, slipping, or even fraying. A compromised belt could cause damage to other parts of your furnace, so it is best to call a technician immediately to investigate. Making the appropriate repairs in a timely manner will help to prevent more costly repairs down the line.


A loud hum from your furnace could be any number of issues, the most common of which would be a problem with the motor. Motor problems could be from dirt or debris getting inside the unit, often when filters are not cleaned regularly. It could also be from a lack of lubrication inside the motor. In either case, this could lead to full motor failure and should be addressed quickly by a technician. If you hear a loud electrical-sounding hum, it could be a problem with a transformer. If this is the case, the electrical transformer may need to be replaced.


A rumbling noise may be cause for concern, as it could be a dangerous issue with the burner. Dirt and grime can accumulate on the gas burners and affect the supply of oxygen to the jets, resulting in a rumbling noise. Corrosion or rust can also be involved in a problem like this. You can often examine the state of the burner yourself to see if dirt or corrosion might be a problem - but cleaning the unit should be left to professionals. Loose equipment on an aging or poorly maintained furnace could also result in rumbling sounds. Loosening belts, nuts, or bolts could quickly become a serious problem and should be examined by your technician.

Reduce furnace noise

Some furnaces will make more noise than others. Often an aging furnace will become noisier that it once was, and older technology was often less efficient in preventing noise from the blower. There are a number of solutions available if your furnace is loud while running, such as sound insulation around the furnace to help muffle the sound of your blower or using air duct noise silencers to quiet the noise escaping through your vents. Contact an HVAC professional to discuss your noise reduction options. Scheduling regular maintenance with a qualified technician is also extremely important to keep your unit running as smoothly as possible. An ounce of prevention is worth a pound of cure!