What to do when your furnace is making loud noises

While functioning, most furnaces make a low humming or rumble noise, and they even make popping or clicking noises. This is absolutely normal. But if the sounds coming out of your furnace are loud, intimidating, threatening and not at all normal, there could be a serious problem with its components. Make sure the issue is looked upon as soon as possible. Ignoring these sounds could later lead to costly repairs or even worse, compel you to buy a new furnace due to breakdown. Here is a list of sounds that are clear indicators that your furnace may need professional inspection.


Squealing or whining noise

A high-pitched squealing noise indicates a minor problem of the blower belt, which may have slipped or has become frayed with time. The belt can be shifted back to its original position or it can be replaced by a technician. Also, the shaft bearings may need oil replacement, but if the blower motor is malfunctioning, then it needs to be replaced.

Loud-scraping sound

If your furnace produces loud-scraping sound, something similar to that of scratching nails on a chalkboard, it is a sure sign that something is wrong with the blower motor wheel. If this sound persists, you should immediately shut your furnace off. It is likely that the blower wheel has become loose and is hitting the blower casing, or the wheel is damaged, in either cases you will have to call a professional technician. It is also possible that the motor mount may be broken, causing the blower assembly to drop and hit the covering.

Loud bang when you turn the furnace on

There are two possible reasons why your furnace is making loud popping or banging sounds:

  • Breathing air-ducts: When there are metal air ducts that are undersized, closed, flimsy or blocked, or the filters are clogged, they cause the vents to contract and expand as air flows. Usually, it is the metal that makes this noise. Installing proper vents will certainly fix the noise problem.

  • Dirty burners: When there is a delay in ignition, excess gas builds up before the burners ignite. This creates small explosions inside the furnace and may cause cracks in the heat exchanger. This issue should be looked upon immediately.

Mild groaning sounds

This sound is usually common in furnaces which are 20 years old. Such groaning sound generally occurs due to worn out motor bearings. You can simply call in a contractor and have the motor bearings in your furnace oiled or replaced.

The sounds that your furnace is making could be due to various reasons, which could lead to bigger, serious problems. This article is a general guide that will help you determine the possible problems that the components of your furnace could possibly be encountering. To avoid any damage of your furnace or your home, make sure you have the problem looked at by an HVAC professional.


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