Why Is My Rheem Tankless Water Heater Beeping

Why Is My Rheem Tankless Water Heater Beeping?

Rheem Tankless Water Heater makes a beeping noise when it detects a problem and alerts you by leaving an error message on the display. Here are some common reasons behind the beep: 

  • Water Leak: A puddle of water near the water heater is an obvious sign of a water leak. 
  • Limescale Buildup on Heat Exchanger: The heat exchanger is responsible for heating the water. If it gets clogged by mineral deposits, your tankless unit will malfunction and make a beeping sound. 
  • Overheating: When the safety sensor senses the unit gets too hot, it will make a beeping noise and display an error code. 
  • Low Water Flow Rate: The tankless unit has a minimum water flow requirement to fire. If it detects insufficient water flow, the tankless water heater will beep to notify you about this issue. 
  • Error Codes Displayed: This is the most prominent reason behind a beeping noise. Your Rheem Tankless Water Heater may throw different beeping codes like 11, 12, 13, or others. Read this article on Rheem Tankless Water Heater Error Codes to discover the meaning of those beeping codes.

Table of Contents

Why Is My Rheem Tankless Water Heater Beeping?

Your Rheem tankless water will beep to alert you about a defective water heater unit. A water heater beeping sound indicates something is going wrong with the unit you need to pay your attention to. 

Generally, the tankless water heater will display an error code after the beeping. And the error message will help you diagnose the unit by finding the source of a specific problem. 

Below, we will mention every reason that is responsible for making a beeping noise. 

01. Water Leakage Detected

A tankless water heater, either from Rheem or other brands, will make a beeping sound once it detects a leak. Every water heater features a water leak sensor. When it senses a leak, it will alert you by producing an audible beep to shield your property against water damage. 

If you notice a puddle of water near or under the water heater unit, understand there is a leak. Sometimes your water heater will go into shut-off mode once it identifies a leak. 

Turns out, water may come out of the heat exchanger or pipelines.  On the other hand, if you notice no visible leaking signs, we recommend you inspect the leak sensor itself. It may send a wrong signal to your water heater if the sensor wiring gets loosened or wet. 

How To Fix: 

Begin with inspecting the heat exchanger or pipework. If water is leaking out of these areas, we recommend you hire a certified plumber to fix these problems. 

On the other hand, if there’s a problem with the leak sensor, you should tighten up its wiring or replace the sensor. Now, a question may arise in your mind- how can I understand the leak sensor is at fault? 

Just shut the unit off and disconnect the leak sensor. Then, turn on your water heater. If your unit operates fine, we bet the sensor is the culprit. Regarding this, you should replace it with a new one. 

02. Develop Limescale Buildups

Water continuously comes and passes through your Rheem water heater. The water contains minerals like calcium and magnesium. If you don’t maintain your water heater unit regularly, these minerals make a home on different components like the heat exchangers. 

It will be a frequent problem if you live in hard water areas. The below image will show you the map of water hardness areas in the United States. 

map of water hardness areas in the USA

Consequently, the pipework and fittings of your  water heater get blocked by calcium buildups. This mineral buildup doesn’t decrease the heating efficiency but also causes the heater to malfunction. 

How To Fix: 

You should descale or flush your tankless water heater to stop the beeping sound caused by calcium deposits. We have a guide on ‘Will Vinegar Damage A Hot Water Heater’ where we break down how to flush the water heater with vinegar. So, we recommend you check that article here to learn how to descale a water heater. 

03. Water Heater Gets Overheated

Like other tankless water heaters, Rheem will also make a warning noise when the unit, especially the heat exchanger, gets overheated. Rheem tankless water heater has a sensor named Overheat Film Wrap. When it senses the ‘heat exchanger’ gets too hot, it will beep and throw the error code 14

Dirty or cracked heat exchanger, a clogged exhaust venting, and improper fuel type are some culprits that cause your Rheem water heater to beep and display the error message 14. 

How To Fix: 

First, inspect the heat exchanger for a crack or dirt as it’s prone to get filthy. Remove the carbon buildup from it or replace this with a new one if it gets damaged. 

Next, check the venting pipe of your Rheem water heater for a clog. If it gets clogged by dirt & debris, we recommend you run a plumbing snake to release the blockage.

04. Low Water Flow Rate

Optimum water heater function will mostly depend on proper flow rate of the water. Every water heater specifies its minimum flow rate by GPM. For example, Rheem Gas Tankless Water Heater (21R452) has 0.26 GPM of minimum water flow rate. 

You can’t turn your water heater on if the flow rate is less than the specified minimum water flow rate. 

Several reasons are responsible for low water flow rate. They are: 

  • Inlet filter gets clogged by dirt and debris.
  • You may fail to install cold water and hot water lines in sequence. 
  • Faucket gets clogged by sediment buildups 
  • Defective flow sensor

How to Fix: 

Start with inspecting the inlet filter for a clog. Remove the dirt, debris, and messes if needed to gain optimum flow rate. Next, make sure you install both cold water and hot water lines in sequence. If not, call a certified plumber to correct the installation. 

Sometimes, you will get a low flow rate due to a clogged faucet. We recommend you inspect the faucket for a sediment buildup (that will slow down the water flow speed) and clean the aerators in the faucket.  

Lastly, don’t forget to check the flow sensor of your Rheem water heater. If it gets damaged, the water flow rate will slow down. 

05. Unit Shuts Off and Throw Error Codes

Most often when something goes wrong with your water heater, it will make a beep, throw an error message, and then, go to shut-off mode. Typically, your water heater will beep the following error codes: 

Note: Your water heater may display other error codes like E5, error code 76, and others. We recommend you check the manual and follow the troubleshooting steps for each specific error message. Either way, you can check this guide on Rheem Tankless Water Heater Error codes where we break down every error message and provide their solution as well. 

Apart from those issues, you may experience the following issues. 

Rheem Tankless Water Heater Thermostat Beeping

Every Rheem electric tankless water heater contains one or two thermostats- upper or lower. It’s a device that controls the electrical current flow to different parts of the water heater. 

First off, this device senses the presence of heat. Secondly, it can control the electrical current and send this current to another thermostat or heating element. If the thermostat fails, your water heater fails to ignite and heat the water. Consequently, it beeps to let you know about the fault. 

We recommend you call a certified plumber to inspect your water heater and replace the thermostat if needed. 

Rheem Water Heater Beeping After Power Outage

After a power outage, may partial power get restored, not complete due to some faults. And your Rheem water heater is one of those affected appliances. We recommend you get a circuit tester to see whether your water heater is getting power or not. 

Tripped circuit breaker, damaged wiring, defective switch board, reset button gets tripped, and burn out heating element can also be the culprits behind this issue. 


Whenever you hear the beeping sound produced by your Rheem tankless water heater, understand it needs your attention. Most often you will see an error code on the display after hearing the beeping alarm. Just check out your manual to know the meaning of the error codes and how you can solve them. 

Fortunately, we revealed almost every reason that causes the water heater to beep. So, start with the mentioned culprits to find out the source of the problems. On the other hand, if your tankless water heater beeps but displays no error code, we recommend you call Rheem Customer Service to get help. 

Read Also:

Rinnai Tankless Water Heater Beeping

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *