How To Quiet A Noisy Furnace Blower: 10 Heater Parts To Fix

HVAC Repairman

Last Updated: April 27, 2022

Coming home to a warm house after long hours spent in the cold is pure bliss, especially during the winter period. You can only achieve this by using different heat source options like a fireplace or a furnace.

A furnace is a motor that operates on a forced warm-air distribution system. 

Most motors make noises during operation, and a furnace is no different. Sometimes, the noise can be a signal of an underlying fault. Irrespective of the cause, these noises can be distracting.

In this article, I will be sharing tips on how to quiet a noisy furnace blower and the possible causes of those noises. If this interests you, then you should read further.

Why is My Furnace Blower Too Loud?

Irritated woman covering her ears

The furnace blower is responsible for releasing hot air produced by the heat exchanger into your home through the air ducts.

This is considered one of the essential components of the furnace, yet easily prone to damage. Whenever the furnace isn't doing its job, the blower is usually the culprit. 

Is your furnace blower too loud? Here are some possible causes:

  1. Faulty Blower Motor

Suppose your furnace blower makes a loud rattling or screeching sound, then the fault usually lies in the blower motor.

The blower motor needs constant lubrication to improve its performance. However, most people owning a furnace do not include annual furnace maintenance in their budget. While this might seem normal, it indeed has its repercussions. Failure to lubricate the blower motor often can cause the blower motor and fan to seize, making loud, disturbing noises.

  1. Damaged Blower Wheel

Sometimes, a piece of dirt can become stuck inside the blower wheel, making it unbalanced and producing a loud scraping noise. This noise usually resembles one caused by two metals going against each other. 

Another cause of this noise is when the blower fan has become loose and creates the sound by hitting against the blower house casing.

This metal scraping noise signifies a severe issue that should not be overlooked.

It is best to quickly contact an HVAC professional to avoid irrevocable damage to your furnace. You might be lucky and end up with only a slightly damaged wheel, or at worst, the fan is broken and needs to be replaced.

  1. Loose Blower Belt

A furnace blower is designed to operate as a belt-driven or direct-driven blower.

A direct-driven blower has its blower wheel and output shaft directly connected without a belt. This blower has the advantage of reduced maintenance costs. This is because the absence of a belt prevents constant repair and replacement.

However, suppose you know that your furnace blower uses a belt. In that case, a squeaking or squealing noise is a big indicator that the belt is loosened. A loosened belt can easily be fixed personally by tightening the belt to the normal. However, if the belt is worn out and needs a replacement, ensure you call a professional for that.

Other Causes of a Noisy Furnace Include:

Furnace motor diagram
  1. Dirty Burners

The burner is the part of the furnace responsible for heat formation.

The heat produced in the burner is sent to the heat exchanger compartment, which converts the heat to air circulated in the environment. But then, these burners tend to get dirty with time due to accumulated dust.

A dirty burner is noticed by a loud bang or boom, especially when the furnace is switched on. You should not ignore the issue of a dirty burner because it can be disastrous. A dirty or faulty burner would delay ignition, causing gas accumulation and often an explosion. 

Fortunately, this issue can easily be avoided by routine furnace maintenance, where professional checks and ensures the burners are neat and functional. It would be best to keep in mind that not all loud boom sounds signify a dirty burner.

Sometimes, an unbalanced air-to-fuel ratio or expanding and contracting metal air ducts due to temperature change, can cause a loud bang sound.

  1. Damaged Heat Exchanger

After the winter season, the furnace most likely becomes a part of our home equipment that consumes space. This is expected as the need for a furnace reduces as winter goes away. However, neglecting your furnace for a long while can cause its parts to become clogged with dirt. These clogged parts would restrict airflow leading to heat buildup in the heat exchanger, especially when the furnace is turned on.

This can cause the heat exchanger to crack or split, releasing a rattling sound. 

People often mistake this problem for a loosened panel or screw as they can also produce a rattling sound. Therefore, if you have ascertained that the noise isn't due to a loose screw, your next bet is a faulty heat exchanger. Calling for a professional should be your following action.

Now that I have established the possible causes of a noisy furnace blower let's dive into how to quieten a noisy furnace blower.

10 Tips on How to Quiet a Noisy Furnace Blower

A faulty furnace blower can range from making a squeaking, rattling, banging, or hissing noise.

You can't ignore these sounds no matter how much you might love to. Ignoring them could put you at harm's risk. The best thing to do is to look for ways to help you achieve a quiet furnace blower. Some helpful tips are:

  1. Tighten Loose Connections of the Motor Mount

The motor is usually connected to the motor mount, which holds it in place to ensure the furnace's proper functioning. Although, over time, vibrations and force can cause this connection to loosen. The screws holding the motor and mount loosen up and generate a rattling sound. Thus, tightening the furnace motor to its mount can reduce the rattling noise resonating from the furnace.

Also, the set screw holding the furnace blower can loosen. This can be due to the constant rotation and vibrations of the blower. Thus, when the set screw is loose, the rotating blower causes a rattling noise. Tightening the set screw would help minimize the noise.

  1. Replacement of Furnace Blower Bearings

The furnace blower has bearings that provide lubrication and smoothness to its operation. But with time, these ball bearings can wear off, and this can cause resistance in the furnace blower. The fan blower can heat up and, along with it, create unusual noise. 

This sound can get amplified due to the ductwork that transfers the hot air. So, check whether the bearings of the furnace blower are worn out and replace them if needed; this can help eliminate the noise.

  1. Replace the Belt Drive

As mentioned earlier, a furnace blower can operate as a belt-driven or direct-drive motor. If yours is a belt-driven motor, these belts can wear and tear over the long term, causing squealing. Ensure you replace any worn-out or frayed belts to eliminate the noise. Perhaps, the belts are only just loosened; tightening them up would be an effective solution. 

  1. Clean the Furnace Blower Fan

The furnace is usually stored in the basement once the winter period is over. Thus, it is bound to accumulate dust and dirt. Little dust might pose no problem. However, when it becomes excessive, it can interrupt the smooth functioning of the furnace.

The blower fan is one essential part of the furnace, usually affected by dust. This creates external air resistance, which makes the noise inside the furnace. An excellent way to prevent this noise is to clean the blower fan regularly, especially during routine maintenance. This helps free the blower fan of dust and dirt that might have found its way into the blower.

  1. Regulate the Furnace Fan Speed

Upon installing a furnace in your home, a professional will help set the furnace fan speed to the optimum. However, this might not be the case in all situations, and sometimes this speed can be set too high and could cause a whooshing sound to be heard.

Even if the fan speed was initially set correctly, calibration errors could occur during routine maintenance. This can lead to an improper setting of the fan speed. Whatever the cause of a wrong fan speed might be, what is important is that you adjust the speed to the optimum level. This reduces the noise associated with high furnace fan speed.

  1. Include Additional Return Air duct

Sometimes, a furnace might not function properly and cause a loud noise if the amount of returning air does not equal the amount of output air.

This frequently happens, thus generating a vacuum in the intake part, restricting proper air movement around the furnace. 

You might be wondering how you can know when the return air isn't sufficient. If you hear a whistling sound that quietens upon opening the air filter door, then the furnace needs more return air. A professional can help you include more return air ducts to improve airflow in the furnace. A porous filter can also help solve the problem.

  1. Replacement of Furnace Blower Motor or Fan Blade

Problems associated with furnace blower motors can hardly be repaired, and the best advice is to get a motor replacement. Motor-related issues are considered serious as they can be harmful if left unattended. 

So, if you have tried all you know to eliminate the noise, and you still get that persistent banging sound. Then, it is most likely a furnace motor-related issue. Therefore, you should replace the motor with a new one.

Sometimes, the fan blade can be broken, bent, or damaged. These blades can't be repaired or managed as they can disrupt the functioning of the furnace. You must replace the blades with new ones of similar size.

  1. Try Sound Insulation Methods

It's almost impossible for motors and machines not to make noise. This is usually inevitable for heavy machines like a furnace. Therefore, if the noise produced by the furnace is pretty challenging to eliminate, then heat-resistant sound insulation can do the magic of soundproofing.

With a piece of galvanized steel or melamine foam, you can effectively minimize the noise made by a furnace.

You have to place them next to the blower intake and make sure that the insulation or parts of it don't get sucked into the furnace. This is a highly effective furnace blower noise reduction technique.

  1. Check for Any Loose Connections in the Furnace

Frequently, a furnace will start to make whistling noises due to a tiny gap between the blower and the ductwork. This is pretty straightforward to fix – the reason the whistling has started is likely because the air filter is clogged.

To ascertain this, remove the air filter. If the whistling sound stops, then you know that all you need to do is replace it. Ensure you do not leave it too long – leaving a clogged air filter will cause your blower fan to wear more quickly.

  1. Get a Professional Help

If we are truthful, most causes of a noisy furnace are pretty difficult to repair without technical know-how. It's always advisable you seek professional help, and after all, that's why they exist.

Even if you decide to check out the furnace for the faults, you might be shocked to discover that they're more severe than you thought. Therefore, your next course of action is to call for help. 

This would ensure that the fault is wholly resolved and worn-out parts are replaced. It's also essential to involve a pro because they can help you discover more defects that are silent albeit very hazardous.

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Conclusion

We honestly can't do without a furnace, especially during winter. You might not necessarily need one if you have another heat source option. But if you're using one, you will know that a furnace needs proper routine maintenance, just like other motors and machines.

However, these motors can develop faults even though you're quite faithful with their maintenance. A faulty furnace is easily detected by the various noises it produces. Some of these faults and noise can be eliminated by the several tips mentioned above.

For those you can't repair, seek professional help. A faulty furnace blower is not something you should ignore!

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