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How to Quiet a Noisy Furnace Blower

How to Quiet a Noisy Furnace Blower

Most people usually find ways of keeping their homes warm and cozy during winter. While some people have inbuilt fireplaces, others have to depend on a furnace or space heaters to ensure that they’re warm during the season.

Although a furnace is a lifesaver during cold weather and can distribute heat throughout the home, it tends to be quite noisy. The noise levels explain why most people who use furnaces prefer storing them in basements.

The good news is that you can make your home more comfortable during the winter season by finding ways to reduce noise from a very loud furnace. Here is how you can quiet a noisy furnace blower:

Why Is My Furnace So Loud When Running?

Having a very loud furnace can be due to various reasons; therefore, it’s best to pinpoint the source of the sound so that you can solve the issue. In addition, it will help if you don’t ignore furnace noises because they might indicate a much more severe problem that could potentially damage the unit.

Common Causes of Loud Furnace Noises

Having a very loud furnace could be due to various reasons. Here are some of the popular reasons:

Dirty Furnace Filter

If your furnace produces a whistling or screeching sound, then its air filter might be clogged with hair, dust, and dirt. So the eerie screech that you hear might just be air desperately trying to get through.

Blower Motor

The blower motor might be another reason for a loud furnace. The blower motor is the blower’s power source that forces warmed air through your ductwork to heat your home. It requires adequate lubrication to ensure that it does its job quietly and properly.

If the blower motor runs too low on oil, it might damage the entire furnace. Therefore, it’s best to lubricate the motor at least once a year by applying two to three drops of motor oil to the oil ports.

Cracked Heat Exchanger

Rattling noise from your furnace could indicate that your heat exchanger is almost dead. When you fail to clean your furnace and change the filter regularly, airflow usually becomes restricted. Eventually, the heat buildup in the furnace could crack the heat exchanger.

A cracked heat exchanger is very hazardous because it can cause carbon monoxide leakage, and the gas is very lethal. If you suspect that a cracked heat exchanger is the cause of a noisy furnace, it’s best to turn off the furnace and get a qualified professional to repair it as soon as possible.

Blower Wheel

The blower wheel, the component powered by the blower motor to move heated air, might sometimes start to make a harsh, scraping, metal-against-metal sound as it rotates. This sound mainly indicates that the blower wheel is out of alignment and might need expert adjustment.

Dirty Burners

If you hear a boom or bang sound that sounds like an explosion a few minutes after switching on your furnace, you might have dirty burners, which cause a delayed ignition. The explosion is a danger signal.

Duct Issues

Your HVAC ducts are made of thin sheet metal, making them excellent at carrying sounds. However, when your duct starts rattling and banging, it might be due to a change in pressure between the supply and return ducts.

Why Is My Furnace Fan Making a Rattling Noise?

A rattling noise from your furnace fan could be something as simple as a loose screw or as severe as a cracked heat exchanger that could result in the leaking of carbon monoxide.

A rattling sound before the blower comes on means a cracked heat exchanger in most cases. It’s best to call an HVAC professional as soon as you detect this problem because it can turn deadly if you ignore it.

However, if you hear a rattling noise while your furnace is on, it’s most likely an indication of loose connections in your duct system. You could try fixing the issue by sealing your ductwork or calling a professional to repair and seal the entire duct system.

The rattling noise might also be due to loose panels that need to be tightened as soon as possible.

How to Make Your Furnace Blower Less Noisy

You can get frustrated easily if your furnace blower is too loud. Some furnace noises require quick action, and it’s best to contact a reliable heating and cooling company to help you sort out any issues. Some of the noises that you should never ignore include the following:

  • Rattling noise: A furnace has several moving parts inside it that can be loose or fall off entirely to the surface. The loose or fallen parts can cause a rattling noise because when you start the furnace, the parts also begin vibrating.
  • High pitched screeching or whistling: This sound often occurs when the belt is loosened in your furnace. Therefore, it’s always best to look at your furnace blower and analyze the problem. Of course, you can always remove the belt to check why it gets loose so much.
  • Rumbling noise: Fuel ignition might be the cause of the rumbling noise from your furnace blower.
  • Banging noise: A banging noise is a pretty common noise problem in furnaces. It usually comes from the duct, vent, and filter area due to dirt buildup or destabilization.
  • Humming noise: A loud humming noise is usually produced by a transformer or fan. It could also happen to your furnace; therefore, you should also look at this area if you hear a humming noise from the furnace.

Here is how you can make your furnace blower less noisy:

Adjust the Fan Speed

A fan usually produces a humming noise; however, there might be many other reasons behind the noise. For example, the furnace’s fan might have a dust and dirt buildup that will require cleaning or the fan might be running at a high level that doesn’t need it.

During the installation of the furnace blower, ensure that it’s configured at the best settings according to your house. Proper installation will help you get better airflow inside the house. However, even with appropriate installation, the speed of the furnace fan might be way higher than the expected flow.

The air pressure reaches its maximum level and produces noise in such scenarios, leaving you with a noisy furnace blower. All you have to do to reduce the noise is decrease the fan speed at the lower level and check the airflow. If it’s okay for you and the furnace blower, set the fan at that level.

Add Return Air Ducts

Sometimes the furnace blower produces a whistle tone from a distance. If you open the air filter door and establish that the noise is reducing, that might indicate that the blower has insufficient return air.

Additionally, it might be generating a vacuum on the intake part rather than pushing the air through the system accordingly. Finally, a high-pressure difference between the intake and output side often leads to a noisy air return.

If you’ve analyzed and established that high-pressure difference is the problem, you can reduce the noise level by adding additional return air ducts. However, you might need to contact a professional to help you replace the air ducts. Additionally, a permeable filter might also boost the airflow in the furnace.

Consider Building Sound Insulation

You can try adding sound insulation to the system to quiet a noisy furnace blower. In addition, you can install melamine foam next to the blower intake and try securing the foam using steel wire so that the furnace blower doesn’t suck it in.

Replace Any Loose Parts

Loose fins on your furnace blower can lead to an annoying noise as the blower runs. If you hear a rattling noise, you should confirm whether the fins are loose. It’s best to consider replacing any loose parts if you don’t have the money to purchase a new blower fan.

You can also consider using duct tape on any other loose part because sometimes a squeaking noise can be due to a loose belt inside the furnace blower. Additionally, if you’ve been using the furnace for a while, it’s best to consider purchasing a new belt to avoid such noises.

Soundproof the Blower Compartment

Suppose your furnace blower starts producing annoying noise after a long time of using it, and you don’t have a budget to replace it with a variable blower. In that case, you should consider making the blower compartment soundproof by using some sort of insulation materials.

You can use an insulation material such as melamine foam next to the blower intake, where most of the noise is coming from. However, it doesn’t have any gum to stick on the blower; therefore, you might have to use the steel wire to secure it in its place.

Fasten the Motor Using Belts

It’s best to look at the condition of the blower motor if you have a very loud furnace blower. You can fasten it to the furnace using bolts and install rubber mounts, which can help reduce noise significantly.

Additionally, confirm if the current rubber mount is worn out or missing and that no fastener is broken. A faulty fastener can lead to a noisy furnace blower.

If the motor bearing is down, you can lubricate it using oil. Additionally, placing your furnace in a room with a concrete floor can cause deafening vibrating sounds. However, you can reduce the noise by placing some rubber pads below the furnace to prevent this.

Be sure to also look at the blower to ascertain that there’s no foreign object inside it because it can also cause noise.

How to Quiet a Furnace Blower in a Mobile Home

A mobile home furnace is too loud when you have to turn the volume up whenever the furnace cycles on and turn the volume down when the furnace goes off.

Mobile home furnaces tend to be very loud due to the proximity and openness of the furnace to the living area. In addition, most mobile homes do not have cold air returns; therefore, insufficient return air ducting is the primary problem leading to mobile home furnace noise.

Here is how you can quiet a furnace blower in a mobile home:

A Larger Filter Can Help Solve the Problem

You can fix a loud mobile home furnace with a larger filter that’s relocated above the furnace and a door over the furnace cavity. You can buy a sheet of beautiful quarter-inch plywood and cut it slightly larger than the furnace cavity.

Cut the plywood to completely cover the furnace opening and fasten it to cover the gap. When doing this, ensure that the plywood has a good seal to keep dust and pet hair from seeping in through the cracks.

You can install a filter grill just above the furnace, taking advantage of the void above the furnace together with the cover over the front of the furnace to create a chamber that will help reduce the noise. Ensure that the filters are as large as possible to allow extended service and the best airflow.

How Do I Lubricate My Furnace Blower Bearings?

Some older furnaces have two blower shaft bearings and two motor bearings that require annual oiling. You can lubricate your furnace blower bearings by following these steps:

  • First, clean around the oil caps and remove the caps.
  • Next, apply two to three drops of lightweight machine oil.
  • Replace the caps.
  • Ensure that you don’t over-lubricate the bearings.

How to Quiet a Noisy Air Return

Having a noisy air return can be frustrating because it can ruin your quiet time and the treasured afternoon naps. While it’s pretty normal for HVAC systems and air ducts to produce some noise, the amount of noise you hear will depend on how close or far you are from the air conditioning system.

What Causes the Noise in Your Air Return?

If you hear noise from your air return, it’s best to confirm the cause of the problem before trying to resolve the issue. The most common reason for a noisy air return is the flanking noise. Flanking noise is the sound that travels through the HVAC system and can be heard far from its source.

Flanking noise can be caused by several things, including loose vents, heat ducts, blower motor, or Lego pieces moving around in a duct.

Here is how you quiet a noisy air return to ensure that you have a peaceful time:

Open the Vents

A single closed vent won’t make much difference; however, your system will get noisier if two or more ducts are closed. If the return air in your home is becoming unbearable, opening the vents should be your first step.

You can also check whether the grill or vent is adjustable. If you can adjust either of them, it’s best to switch to the most open position to ensure maximum airflow.

It’s best to check the vents regularly to ensure they aren’t closed because closed vents are most likely to put undue pressure on your HVAC and eventually compromise it.

Clean the Filters/ Air Ducts

If you open the vents but still hear yourself over the return air noise, you might need to check the filters or air ducts.

Ducts and filters cover air returns. When air is sucked into the vents, dust and other particles are likely to get trapped in the filters, leading to clogging, especially if the return vents are installed in dusty rooms.

If you have clogged filters, your air return is likely to have a more challenging time moving air, resulting in a noisier system. The best way to solve this issue is to ensure that you clean and change the filters as often as possible, for example, once a month.

You don’t have to worry about filter prices because they are pretty affordable. Additionally, you don’t need to hire a professional to help you replace them.

You can clean the filters using a vacuum to suck dust, cobwebs, and other debris. However, if simple cleaning doesn’t help, you can remove the grill and clean it deeper. Once you’ve cleaned the grill, vacuum the duct opening to eliminate other things that might clog the system.

Resolve Ductwork Issues

It’s best to establish if your home has inefficient or poorly installed ductwork. If it has any problems, much air might be forced into a limited space, causing a whooshing or whistling sound. The best way of correcting this issue is to sort the ductwork by either fixing the poor installation or ensuring the available ones can handle your system.

If you have a more extensive system, it’s prudent to get a professional to check your house to ensure that the ductwork can handle the airflow. You can also opt for some Fiberglass duct liners to deal with the noisy system.

It’s best to note that hard ducts can be noisier than flexible ones because air moving against metal will be louder. However, flexible ducts are not perfect; while they are made with a more friendly material, they are more prone to kinks and bends, resulting in reduced airflow.

If you opt for hard ducts, it’s prudent to ensure that they are the correct size. If you choose flexible ducts, ensure that you install them with optimal airflow in mind.

Choose the Right Grills and Vents

If you have a noisy air return, you should ensure that you have vents and grills in suitable shapes and sizes. A good vent has an ample opening that ensures air enters easily. Additionally, the vents should not close so easily to ensure that your system is not overwhelmed.

It’s best to correct restrictive vents and grills because they lead to a noisy air return and can strain the cooling and heating systems. It’s best to get a professional to check and replace existing grills and vents.

Reduce the Static Pressure

Some systems might come with too much static pressure that often manifests when the air volume is too high for the ducts to handle comfortably.

While high static pressure is pretty standard, the solution is not the same for every home. It’s best to find a professional to determine a unique solution that’s suitable for your home.

Here are some of the possible solutions in case of static pressure:

  • First, adjust the fan speed to a level that’s suitable for your HVAC system. This solution can only work if the speed is too high because reducing speed in a system set adequately will reduce airflow and the overall performance.
  • Add ductwork to expand the supply and return plenums. In addition, increasing ductwork will help reduce the static pressure, leading to a quieter system.
  • Get a bypass duct if yours is a single multiple-zone system. This solution will significantly reduce the static pressure.
  • Increase the return air capacity by adding registers and increasing the grille size.
  • Switch the current registers and grilles with high-velocity ones.

Get a Variable Speed Blower

A variable-speed blower is an excellent solution, especially if you’re in the process of replacing your HVAC system. Having a variable speed blower means that the air in your home will be circulating more consistently, and less air will be going through the ducts.

The speed might vary depending on your home’s cooling and heating demands. However, variable speed blowers mainly operate at low speeds most of the time; therefore, you will barely hear the system running.

Fix the Central Return Problem

Most small homes usually have a central return. Most of the time, the air handler or the furnace is generally fitted next to the return plenum.

If you have such a home, keeping the system quiet might be quite a challenge because the blower motor is close, and the limited space might not allow the installation of extra ductwork.

Sometimes the problem might have nothing to do with the system, and you might have to think about space and design. If there is a way you can rearrange the system, then you can resolve the problem.

Check this too: How to Make a Toilet Flush Quietly

For example, if you have an air handler installed right behind a bedroom, you can change it to a more favorable location.

You can also solve the issue if space allows you to install more ductwork.

If your furnace sounds like a vacuum or if your new furnace is louder than the old one, you could try the solutions above to quiet it. However, you might have to call a professional HVAC company if none of the above solutions work. After all, an HVAC is a pretty complicated system; therefore, it might be best to let professionals handle any complex matters.