Rheem Tankless Water Heater Noise – 3 Causes

We all love access to a warmer water temperature. Whether it be for showers after summer pool parties or washing up dishes and getting clean clothes, access to hot flow of water from a Rheem tankless water heater is a delight—until you hear that humming. The endless humming.

When is a Rheem heater too noisy? There’s a problem with the water heater when the noise levels are loud enough to disrupt your home activities on a regular basis.

Rheem tankless water heaters may make a lot of noises, from humming to banging to a high frequency sound. Causes include water leaks, open valves, and loose components.

This article will guide and explore everything about Rheem tankless water heater noise. 

My Rheem Tankless Water Heater Is Making Noise—Is This Normal?

An excellent tankless heater is just as noisy as a desktop CPU. You will hear the distinct humming sound when you switch it on. Most people will describe the sound as mild and bearable.

In most cases, you can’t hear it working unless you are paying attention. Rheem tankless water heaters may operate within a 49 to 65db noise level. 

Tankless water heaters often get noisy when there’s a component problem. However, it is concerning when the noise levels disrupt your activities. 

Rheem Tankless Water Heater Noise

Why Is My Rheem Tankless Water Heater Making So Much Noise? 

There’s a problem if your Rheem tankless water heaters are noisy. It may get loud when the vacuum is suctioning off water from the appliance. 

A defective valve in the water line, a faulty flow sensor—which regulates the inflow of gas and water into the heater—and poor installation can all contribute to excess noise in Rheem water heaters.

It matters whether you installed the unit directly on the wall or in a protective box. The unit vibrating against the wall can also double the noise level. 

As you can see, there are many reasons why your Rheem heater is noisy. A noisy heater is quite common. However, pay attention when your heater produces specific sounds like screeching or humming.

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Why Is My Rheem Tankless Water Heater Humming?

Does it seem like you’ve got a bee in your heater? 

A loose water element is responsible for that humming sound. The elements in a heater must be in a vertical position relative to the heater. Water flowing around the element can cause minor vibrations and a humming sound. 

Why Is My Rheem Tankless Water Heater Making a Knocking Noise? 

Heaters produce hammering or knocking sounds when the internal pipes are overheating and hitting the walls. Although this is not a severe problem, it could lead to serious wall damage. Plumbers may install a water hammer arrestor to fix this issue. 

Why Is My Rheem Tankless Hot Water Heater Making a Screeching or Hissing Noise? 

A hissing sound indicates a leak that requires the help of a plumber. And those annoying screeching sounds? A half-opened valve might be letting high-pressure water flow through a small opening, creating screeching.

How to Reduce Rheem Tankless Water Heater Noise

As a DIYer, it’s not enough to identify the reasons behind a noisy water heater. Your next step should focus on how to fix it without the need to hire a plumber. Most DIY solutions involve tightening loose joints, flushing with vinegar, or fully opening inlet and water valves in a water heater. 

Follow these guidelines when fixing a hot water heater noise level. 

Identify the Source

Identify the root cause before tampering with the appliance. Start with identifying the noise type. Is it a screeching or a humming sound? Each sound type is indicative of a specific problem.

For example, heaters make ticking sounds when there’s a problem with the water pressure. Likewise, a cracking or hissing noise indicates a sediment buildup in the unit. Furthermore, there’s a blocked water valve if you hear a screeching sound. 

Find Solutions for Your Specific Problem

Is a loose water heater part responsible for the problem? Identify the loose component and use a wrench to tighten it. Be cautious when tampering with a heater. It’s alright to call a service technician if you’re unsure of how to get it done. 

Check the Water Valve if There’s a Screeching Sound

Remove the obstacle and open the valve. Rotate the valve knob counterclockwise until it is fully open. Have a professional plumber check the water supply lines and pressure valve if the problem persists. 

Flush Out Sediment Buildup with Vinegar

There are rare cases when sediments cover the heating element entirely. For such situations, unscrew the heating element from the unit. Then dip it in vinegar for a few minutes before scrubbing with a wire brush

You can solve banging or hammering noise by tightening the clamps on pipes leading to the heater. Use dampeners like rubber or wool to solve noises caused by vibrations. The dampeners will muffle the sounds and reduce the vibration to unnoticeable levels. 

How Do I Avoid Rheem Tankless Water Noise? 

To avoid all these distracting noises from your heater, make sure to perform regular maintenance on the inlet valves, look for loose parts or straps, and flush the heating system at least once per year. You can also install an audio muffler or belts to reduce vibrations.


There you have it: an all-you-need guide to fix those annoying water heater sounds. Share these tips with others facing these issues. Don’t forget to consult a professional plumber when unsure how to resolve these issues.