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Furnace Humming and What It Means for Your Home

Every appliance is known to make some degree of noise, but a humming furnace could be the sign of a more significant issue. Homeowners who hear a loud furnace humming should be sure to call out their local repairman to take a closer look at what is going on within the unit. The possible causes could range from broken pieces to loose equipment.

Consulting a professional is the only way to truly know for sure why your furnace is making such a racket. However, when you start hearing your furnace making a humming noise, here are a few of the most likely culprits.

Failed Blower

One of the most common causes of furnace humming is a failed blower. This blower is like the motor of your machine, pushing warm air through the ductwork and into your home. When you hear the furnace making a humming noise, it could be a sign that your blower won’t last much longer.

Of course, different types of humming sounds can mean various issues with the blower. It could be a sign of low amperage. Cleaning the debris out of the unit could solve this issue rather quickly without the major cost investment of purchasing a new blower. This is something that should be done annually to keep your furnace in its best shape.

In other scenarios, a sudden humming sound might indicate that your motor is about to fail altogether. Regardless of what sort of furnace humming you hear, it is best to consult a professional for more advice. They can guide you in the right direction when it comes to purchasing a new blower as well.

A Broken Capacitor

Can you hear the motor humming but hear it stop short of turning over? This is likely a sign that your capacitor incurred some damage. Replacing the capacitor and cleaning the filter should be enough to get your furnace up and running again without the annoying humming sound.

Along this same vein, another sign that you might need a new capacitor comes when your blower slows down too much. Once the furnace has sufficiently warmed the home, it is typical for the blower to slow down.

If you encounter an extremely low airflow accompanied by this furnace humming, it is likely caused by a broken capacitator. Both the motor and the capacitor will likely need to be replaced to get things running smoothly once again.

Electrical Current in the Transformer

The transformer in your furnace can also produce a humming sound when electricity passes through. The current causes the transform to vibrate and results in the humming noise that has been driving you crazy.

As the hum grows louder, it could be a sign that your transformer is about to fail and will need professional attention. Alternatively, it may simply need the bolts tightened. It is quite possible that your furnace is making this sound despite there being no real issue.

Low humming noise in the furnace when it’s off could be caused by the transformer and the attached ductwork. Enlisting the help of a professional to reposition the transformer could resolve your issue.

Dirty Burners

When is the last time you had your furnace serviced by a professional? It is generally recommended that you have someone inspect your furnace at least once each year.

During this time, they are able to adjust parts, add lubrication, and clean out the debris that can accumulate in the furnace. One of the primary causes of a humming furnace is dirty gas burners. A thorough cleaning should be enough to eradicate the sound for good.

Furnace Blower Motor Hums but Won’t Start

This is an extremely common issue that homeowners face. You can clearly hear the furnace blower motor hum, but it won’t start. This can typically be attributed to your pilot light. In order to correct the issue, you simply need to readjust the pilot light to the correct level. Once this is done, the humming should correct itself.


If your home is a little older, it is quite possible that the humming sound doesn’t originate with your furnace at all. Ductwork and air returns are frequently made of very thin materials that have some give to them over the years.

The seams on these pieces of sheet metal may allow that warm air to flow through the holes, creating a humming sound. To fix the problem, you simply need to shore up or replace ductwork that is coming apart at the seams.

Pinpointing Why the Furnace is Humming

When it comes to the exact reason why your furnace is humming, it can be difficult to pinpoint. Problems can range from extensive to rather simple. You might need an entire overhaul of the system or just a few minor tweaks.

Regardless of what your furnace might need, trust your home to the professionals. They can assist with finding the problem and correcting it safely for years of winter warmth.

Don’t let a humming furnace stop you from enjoying the warmth this winter. Take care of your potential issue today!

Michael Joseph