How To Reduce Noise From A Tankless Water Heater (12-Step Guide)

Licensed Inspector Arie Van Tuijl
Licensed Inspector Arie Van Tuijl

🕖Last Updated On May 10, 2022

If you want to reduce tankless water heater noises, you are in the right spot! 

In this guide, you'll discover:

  • Cleaning the fan reduces noise
  • Why a loose heating element hums
  • Installing anti-vibration mounts
  • And more tips!
how to reduce noise from tankless water heater

There is nothing more annoying than a loud and annoying tankless water heater. Sometimes the vibrations alone can travel throughout a home as if a freight train were passing through.

But there are a few simple things you can check in order to eliminate or reduce the noise. 

Let's get started with our 12-steps to reduce noise from tankless water heaters!

What You Need To Know About Reducing Noise From Tankless Water Heaters

The most common way to reduce noise from a tankless water heater is to clean debris from the fan.

Every gas fired tankless water heater will have a blower fan (squirrel cage or centrifugal fan) that blows exhaust through the pipe to the outside.

Well, believe it or not, but insects and lizards frequently crawl into the tankless heater and get stuck inside the fan. This will cause the centrifugal fan to become unbalanced and make a lot of noise.

Safety Considerations

We recommend that some of these steps should be done by a qualified contractor, and always be careful that you aren't voiding a warranty by doing some of these noise-reducing steps.

It is also important to always turn off power to the tankless water heater (unplug it) before you take off the cover and diagnose noise problems.

Supplies You'll Need To Reduce Tankless Water Heater Noise

  • Screwdriver - A simple flathead or Phillips screwdriver will be needed to remove the front cover of the tankless water heater. A screwdriver will also be used to remove the blower fan.
  • Anti-Vibration Mounts & Bracket - These rubber mounts and isolation bracket will be needed if you want to isolate the tankless unit from the wall to reduce noise.
  • Can of Compressed Air - A compressed air can will be used to clean debris (such as insects) from inside the blower fan.
  • Water Hammer Arrestor - A water hammer arrestor will be needed to fix any water hammer problems associated with the tankless water heater.

Read Also >> How To Flush A Tankless Water Heater?

How To Reduce Noise From A Tankless Water Heater (12-Step Guide)

  1. Check The Blower Fan For Insects And Lizards
  2. Check The Blower Fan For Proper Balancing
  3. Check The Pressure Relief Valve If There Is A Tea Kettle Sound
  4. Install Anti-Vibration Mounts
  5. Soundproof The Area Around The Tankless Water Heater
  6. Have A Pro Adjust The Flame And Fan Intensity
  7. Verify That You Don't Have A Hot Water Leak Causing Short Cycling
  8. Check For A Loose Heating Element That Causes Humming
  9. Inspect For A Dirty Flow Sensor
  10. Verify That Other Fixtures Aren't Siphoning Away Water
  11. High Pitched Sounds Can Be From Incompletely Opened Valves
  12. Loud Water Hammer Sounds From the Tankless Water Heater

Step 1 - Check The Blower Fan For Insects And Lizards

Check the fan inside the tankless water heater for insects and lizards.

The most common reason for unusually loud noises from a tankless water heater is due to insects inside the blower fan. Insects (or small lizards) can make their way into the tankless heater and get stuck inside the blower fan. These critters will cause the blower fan to become unbalanced and it can cause a racket.

To get to the fan, first unplug the tankless water heater, and then remove the cover.

The blower fan will likely have a few screws that need to be removed, and then you can gently pull it out. If you have to remove any wiring, we recommend that you take a picture of the wiring with your phone prior to removal.

A can of compressed air works well to remove insects and debris from the fan.

Step 2 - Check The Blower Fan For Proper Balancing

Check the fan inside of the tankless water heater for proper balancing.

Even if the blower fan doesn't have any debris or insects, it still may be unbalanced and leading to loud noises. After you have pulled out the blower fan, push the fan blades and see if it spins smoothly and in one direction.

If it doesn't spin correctly, you may need a new fan.

Read Also >> What Are The Highest Rated Condensing Tankless Water Heaters?

Step 3 - Check The Pressure Relief Valve If There Is A Tea Kettle Sound

Inspect the pressure relief valve on the tankless unit if you get a 'tea kettle' sound.

Sometimes homeowners get a tea kettle sound coming from the tankless water heater when they turn it off.

This odd sound can be from a partially open pressure relief valve on a gas tankless unit.

The sound is coming from the release of pressure from this valve that happens when you turn off the heater.

Step 4 - Install Anti-Vibration Mounts

Install the tankless water heater with anti-vibration mounts to reduce noise.

Anti-vibration mounts are made out of neoprene or rubber which helps to reduce noise.

These mounts also typically come with a bracket and it isolates the tankless water heater from the wall to reduce vibrations. If you don't want to install anti-vibration mounts, you can also just install a rubber mat or foam in-between the wall and the tankless heater.

Step 5 - Soundproof The Area Around The Tankless Water Heater

Install soundproofing material around the tankless water heater.

Homeowners can install 5/8" drywall, rockwool insulation, and use acoustic caulking in order reduce noise.

Read Also >> How To Adjust The Temperature On A Rinnai Tankless Water Heater?

Step 6 - Have A Pro Adjust The Flame And Fan Intensity

Have a professional plumber or tech adjust the settings inside of the tankless water heater.

If you have a flame or fan that is improperly adjusted, it can make a lot of loud noises due to improper calibration.

This step should be left to the pros since it requires advanced knowledge of tankless heater operation.

Step 7 - Verify That You Don't Have A Hot Water Leak Causing Short Cycling

Make sure that there isn't a hot water leak that causes the tankless water heater to constantly turn on.

If your tankless heater is short cycling, and always making sounds, then you may have a hot water leak which signals to the tankless heater to turn on. It is as if someone is constantly opening a hot water faucet.

The easiest way to know if there is a hot water leak is to shutoff the cold water valve to the tankless water heater. 

Wait two minutes, and then quickly turn the cold water valve back on. If water rushes through the valve, then you know there is a hot water leak somewhere.

This exercise creates a 'closed loop' and if there is no leak, then water won't rush through the valve when opened. Homeowners also need to make sure that there are no drip leaks at any faucets in the home.

Read Also >> What Size Tankless Water Heater Do I Need?

Step 8 - Check For A Loose Heating Element That Causes Humming

Humming sounds are typically caused by a loose heating element.

If you get humming sounds, you will simply need to tighten up the heating element.

Always unplug the tankless water heater before tightening up screws inside the unit.

Step 9 - Inspect For A Dirty Flow Sensor

The flow sensor regulates the amount of gas that goes to the tankless water heater during operation.

If this sensor is dirty, it can cause fluctuations in the gas intensity and lead to loud sounds.

Step 10 - Verify That Other Fixtures Aren't Siphoning Away Water

Homeowners should verify that other plumbing fixtures aren't siphoning away water which leads to loud vibrations and noise.

If the tankless water heater isn't being used, but it still makes loud sounds, it may be from water siphoning.

The easiest solution to stop siphoning action from other fixtures is to install a check valve.

Read Also >> What Are The Best Tankless Water Heaters For Cold Climates?

Step 11 - High Pitched Sounds Can Be From Incompletely Opened Valves

If there is a screeching or high pitched sound coming from your tankless unit or near it, it may be from a water valve.

The water valve may only be partially open which leads to loud screeching sounds.

Make sure that the water valves at the tankless water heater are fully open.

how to reduce noise from a tankless water heater

Step 12 - Loud Water Hammer Sounds From the Tankless Water Heater

Water hammer near the tankless water heater can make annoying loud sounds.

Water hammer happens when there is too much pressure in the water pipe which leads to vibrations. These vibrations will bang against the wall and studs leading to extremely loud sounds.

The simplest fix for water hammer is to install water hammer arrestors which are just short pieces of pipe that allow the pressure to be released.

Frequently Asked Questions On Tankless Water Heater Noise

Why is my tankless water heater so noisy?

A noisy tankless water heater is frequently due to a dirty blower fan which may have insects dead inside.

Taking the fan out of the tankless water heater and cleaning it with a can of compressed air will solve a lot of noise problems.

Do tankless hot water heaters make noise?

All tankless water heaters make some noise when they turn on and heat water.

However, if the sounds are extremely loud or unusual (or happening when no hot water is being used in the home) then there are likely some problems that need to be addressed such as a dirty fan, a dirty flow sensor, or blocked ventilation.

How can I soundproof my tankless water heater?

The best way to soundproof a tankless water heater is to install it on the wall with anti-vibration neoprene mounts and an isolation bracket.

The bracket and rubber mounts will isolate the tankless heater from the wall and reduce noise.

Why does my tankless water heater moan?

Moans from a tankless water heater may be due to siphoning of water from other plumbing fixtures.

If you aren't using hot water, but just using a toilet, then the moans may be from water being pulled out of the tankless water heater.

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