Why Is My Furnace Making a Loud Noise and Shaking while It Is On?

Hearing noises coming from your furnace quickly invites your attention to check it and see what’s wrong. Some noises are ignorable since as the furnace gets old it does make all sorts of sounds. However, knowing what’s normal and what’s not—like a squeaking or whistling sound—is important.

Certain noises indicate danger. Loud and unusual noises usually require immediate action. Also, there are furnace sounds you should never ignore as it can escalate and cause potential damage to your home. It is also important from the point of view of electrical safety.

There are many reasons why your furnace is making all sorts of noises. In this article, we have listed the sounds you shouldn’t ignore as it can be a sign of trouble. Let’s see some of them:

Whistling Noise

There are several possible sources of whistling noise from your furnace. It may be due to:

Clogged or Dirty Filter

Having a clogged or dirty filter creates odd sounds like whistling noise. Try removing the filter and see if there is still noise. If the whistling stops, then it’s best to change it immediately. Air filters should be replaced at least in 1-3 months. Changing it will also improve indoor air quality and increased airflow.


If after removing the filter, there’s still noise—try to observe what is causing it. The air duct may now be the culprit as it might have dirt build-up that clogs your air filter. It needs to be cleaned to allow smooth airflow.

Moreover, the duct produces a noise when there is a high static pressure and cannot accommodate air volume that flows in it. You may need to fix it by adjusting the fan speed or adding a ductwork expanding grill to reduce noise. Also, when ducts are small it could produce whistling noise, as the furnace requires greater airflow, it needs bigger ducts to accommodate the air.

Blower Motor

Blower motor produces some noise if it is not properly lubricated. It could also mean imminent motor damage. Immediate cleaning should be done as dirt may have accumulated inside the unit or its components.

Loosed Equipment

Having an old furnace in your home would likely have loosened parts such as nuts and bolts. If you are unsure about this or not confident enough to properly check your furnace, it is best to have a licensed HVAC specialist inspect it for you.

Oil-canning Ductwork

If you think that the noise is coming from the oil canning ductwork. It’s better to pay attention to the furnace to inspect if the banging is happening inside the duct. Now, if pinpointed that the oil canning is the culprit then there may be a weak spot in the ducts that require support and AC Repair is necessary then.


A vibrating sound occurs mostly due to loosened and old parts of the:


This is the usual cause of vibrating sound. Normally, vibration occurs in the loose accessed panel and frame of the furnace. Thus, it can be fixed by putting a cork pad or rubber underneath the furnace.


Ordinarily, when there is air blockage on the duct wall, it vibrates and rattles. This is especially if you have a clogged air filter and loose ducts.

Banging When the Furnace Turns On

A banging sound when your furnace starts up is a common indicator that your furnace has:

Grimmy furnace burner

When your burner is full of dirt it causes burner ignition delay. As a result, there is a gas buildup in the air once turned on and when ignited it makes a loud banging noise like a mini-explosion. This should not be ignored as it can crack your heat exchanger. Sometimes, it creates even bigger flames too.

Enlarged air ducts

Hearing a banging noise once your furnace starts may indicate that your duct may be the problem. Air ducts expand and contract due to increased pressure. This needs to be repaired. Ordinarily, the usual problems of troubled air ducts are undersized ducts, closed vents, dirty air filters, and flimsy ducts.

Motor Noise

If loud or screeching noise comes from your furnace motor, it can be due to a lack of lubrication. It can be fixed by removing the motor and adding some oil to run it smoothly again.

It’s possible too that it is due to bouncing. This can be fixed by putting a solid piece of styrofoam in its cage. However, if the problem is its bearings being worn down, you may need an HVAC specialist.

Another likely reason too is it could be that the motor belt is worn out or stretched. This can be repaired by removing the loosened belt and replacing it with a new one.

Squeaking When You Walk On the Floor

There can be two instances why there is a banging or squeaking sound as you walk through the floor near the furnace. Either the duct is too tight or the metal panning is not nailed up properly.

It can be solved by:

  • Duct reinforcement with oil canning ducts
  • Re-hanging the duct
  • Duct replacement with Thermo-Pan
Steve Max
Steve Maxhttp://www.webzando.com/
A long time digital entrepreneur, Steve has been in digital marketing since 2010 and over the past decade he has built & executed innovative online strategies for leading companies in car insurance, retail shopping, professional sports and the movie & television industry.


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