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Why Does My Furnace Make a Whining Noise?

Why Does Furnace Make a Whining Noise
Posted on December 12, 2013
by Appleby Systems

Cold weather has arrived, and you turn on your furnace for the first time in several months.

It appears to be working, but there is now a whining noise that is making you nervous (and driving you crazy).

This is a common problem that our technicians deal with frequently.

What Causes that Horrible Sound?

A whining (or grinding, screeching, banging) sound coming from a furnace is usually the result of a moving part beginning to fail -  most often:

  • The ventor motor, or
  • Circulating fan motor.

All furnaces being manufactured today are high-efficiency models.

Previously, mid-efficiency furnaces were available as well. Whether you have an older or newer furnace, all models possess these 2 types of motors.

Ventor Motor Issues

The ventor motor, located in the middle of the top of the inside of the furnace, provides positive ventilation to exhaust the spent air to the outside.

If this important part does not operate, the furnace heat cycle will not start.

  • This is a safety procedure to prevent poisonous exhaust fumes from entering the house during combustion.

Attached to the ventor fan is a pressure switch which will shut the ventor fan off if the vent pipe is blocked.

For instance, deep snow may cover the opening in the vent pipe on the side of the house, thus preventing the exhaust from venting correctly.

In this case, the ventor motor would start and then shut off when the pressure in the vent pipe increases and trips the pressure switch.

Home High Efficiency Furnace With A Residential Gas Water Heater Picture Id1276358762

Circulating Fan Motor Issues

The circulating blower fan motor moves the air through the duct system either in the auto setting or the constant on setting.

The circulating blower is located at the bottom of the furnace.

These electric motors may develop a noise when operating which is an indication that the unit needs service or needs to be replaced.

If the furnace has not been serviced on a regular basis, the fan blades or squirrel cage may become:

  • Warped.
  • Damaged
  • Blocked with dirt.

Any of the above may contribute to a noisy operation.

Is There an Awful Sound Coming from Your Furnace? Don't Wait. Contact Us Now

To determine the cause of any unusual noise coming from the furnace a trained, licensed technician should be contacted.

  • Repairs of this type are not a homeowner do-it-yourself project.

Contact us today to book your furnace service.

furnace maintenance

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