A loud furnace isn't just annoying; it can also be a sign of potential dangers. To identify why your furnace is so loud, it's helpful to name the type of noise that you're hearing. These noises fall into several categories.

Whistling, Squeaking, and Squealing
Squeaking or squealing may be due to a loose fan belt or lack of lubricant. Whistling may indicate that air is escaping somewhere. The blower may be pushing air through the ducts too forcefully, or ducts may not be attached securely.

Thumping, Rattling, and Banging
Thumping is usually caused by an unbalanced blower wheel and occasionally by an unbalanced motor. Left unchecked, this could damage your furnace. Banging can result from the start-stop cycle, which causes metal walls to bend in and out, and may be due to a duct, filter, or vent issue. Rattling or banging may also happen if your heat exchanger is cracked, especially if you hear it just before the blower comes on. This can lead to a dangerous carbon monoxide leak. Rattling can occasionally result from loose panels.

Humming or Rumbling
Humming can be caused by the transformer, capacitor, or fan. Your furnace may still work properly with a loud transformer. Rumbling may be a sign of burner issues. Turn off the furnace and call a professional heating and cooling company if the rumbling persists.

Scraping
The sound of scraping metal can be caused by a broken blower wheel motor mount or a blower wheel that's loose and scraping against its housing. The wheel and housing can become damaged if not quickly repaired.

For many of these issues, you'll need an experienced heating and cooling company such as Maple Air located in Vaughan, to diagnose and repair the problem or replace your heater. However, you may be able to troubleshoot the issue yourself. A physical examination may reveal obvious problems such as a panel you can tighten yourself. You can also turn off your furnace, open the access panel and examine the filter. If it's dirty, replacing the filter may result in quieter operations.

Because of the potential dangers to your health and furnace, you should contact us right away if your furnace starts making loud noises.