Why Is Tankless Water Heater Beeping? Causes & Solutions

If you recently installed a tankless water heater and notice it emits a beeping sound, there could be numerous reasons behind it.

Most likely someone was trying to use the wrong size, run out of fuel, improper venting, sediment buildups, etc.

Don’t worry we are going to provide you the multiple causes and solutions so that you don’t need to hire a plumber.

Why Is Tankless Water Heater Beeping?

The following could be the major reasons for beeping your tankless water heater.

The Size Of The Tankless Water Heater Is Too Small For Your Home:

It is very important to select the right size of the tankless water heater if you want to get rid of this beeping sound.

The rate at which your tankless will heat up water depends upon the BTU rating that it has. So, if you have selected a smaller sized unit then there are chances that it cannot heat enough amount of water. Thus, water begins to flow slower and emits a beeping sound.

Solution: Replacing a larger unit is the only solution to this problem.

Faulty Thermostat:

If there comes an instance where your system beeps and displays an “E1” code, upon checking you may notice that the room temperature is high enough. In such a case, your thermostat is probably faulty and will need replacing.

Solution: Replacing the thermostat is the only potential solution to this problem

Improper Venting:

Proper venting is required on all tankless water heaters for quick and efficient performance.

If you find your device not working properly and the room temperature is normal, there’s a great chance that venting is obstructed. So make sure it is free of clogs or blockages to prevent this type of inconvenience from occurring again.

Solutions: You have to clean your vent with a small brush. Faulty or obstructed condensate drainage system.

Check out our detailed guide to vent your tankless water heater

Internal or External Leakage:

Your tankless water heater could beep continuously if it detects leakage since water leakage is an indication of external damage or internal damage.

It can also occur due to internal corrosion or loss of connections. If it happens, there’s an urgent need to turn off the power supply in order to prevent any further damage.


Internal Damage:

Take a closer look at the inner mechanism of your unite and try to resolve the problem. If you don’t know how to go about doing so, contact a professional or take help from tankless water heater repair.

External damage:

It might be possible that there’s something wrong with the exterior of your device. you can easily find the external leakage there is no need to hire a professional for that.

Extremely High Pressure:

Extremely low pressure could be the possible reason that your unite is continuously beeping, make sure to check out the pressure valves before making any major changes.

Solution: Make sure your water pressure is between 80-120 psi.


This is another issue that typically occurs due to the misuse of gas outdoor boilers. If your tankless water heater starts its ‘Overheat Protection Shutdown’ routine, it may give audible warnings until you turn the unit off or reset it.

Solution: Wait until the device cools down and then turn it on again.

Improper wiring:

Most tankless water heaters are equipped with a 240-volt plug, but if you try to install a 120-volt plug for it, your unit will turn on its error mode and begin beeping until you reset it or call the support team.

If any of these issues occur with your tankless water heater, there’s no need to panic as we have provided a detailed guide to reset your tankless unit.

Solution: Read the manual or call customer service o get the exact idea to do perfect wiring.

Low Flow rate:

Your tankless water heater emits a long beeping sound if it detects a low flow rate. This might happen for several reasons.

It could be that the inlet or outlet valves are not fully open or there’s an obstruction in the pipework that needs to be resolved immediately.

Solution: Check the inlet and outlet valves to find out if they are fully open.

Sediments buildups:

A noisy tankless water heater is also caused due to sediments buildups in the tank. Since these are made up of minerals that are found in hard water, the sediment forms when the heating process begins.

This type of noise blockage can be removed by using abrasive cleaners or vinegar or you can use a water softener as well to prevent sediments for a long time.

Solution: Use vinegar or abrasive cleaners to remove the sediments from your tankless water heater. we have written a guide about the flushing of a tankless water heater make sure to visit that.

Low Fuel:

lower fuel may be a potential cause of beeping in the gas unite, make sure to check out the fuel before performing any action.

Solution: Check your propane tank or gas supply lines.

Look for error code:

Make sure to locate the LED display and look for error code E-1. If there is any, it means your unit is in its default mode and emits a beeping sound until you reset it or contact customer service.

Solution: Reset the unit by pressing the ‘ON’ button for 10 seconds.

Top 3 Best Tankless Water Heaters According to our survey

We conducted a survey based on 387 people living in low, mild, and extremely cold areas. Based on the data, we have found the top 3 best tankless water heaters according to those people.

#1 .Stiebel Eltron Tempra Plus 36 KW –Best Electric Tankless Water Heater for Whole House

Stiebel Eltron Tempra 36


  • 15-20% savings from the hot portion of the electric bill
  • Operates at 99% energy efficiency.
  • 3.7 Gallons of hot water per minute (GPM).
  • 0.77 GPM minimum flow required to activate the unit.
  • 86 TO 140 degrees Fahrenheit output water temperature range.
  • Does not require venting parts.
  • Less expensive to install compared to gas tankless water heaters.
  • Advanced flow control.
  • 3 x 50 A DP min: required breakers.

#1. Rinnai RU199iN Sensei Super – Top Rated Tankless Water Heater

Rinnai RU199iN


  • Up to 11GPM with 15000 BTU (minimum)/ 199000 BTU (maximum).
  • Efficiency 93 to 96% on natural gas.
  • Cric-logic technology to maintain comfort according to your habits.
  • A digital meter to adjust the temperature manually.
  • Compact size to adjust anywhere.
  • Built-in Wi-Fi.
  • Two-inch most flexible venting options.

#2. EcoSmart ECO 27 Tankless Water Heater

EcoSmart ECO 27


  • Saves 50% energy bills with 99.8% efficiency.
  • Comes with durable Components of stainless steel and copper.
  • Digital temperature meter to adjust the temperature.
  •  Supply 3 GPM (gallon per minute) in the coldest places.
  • Supply 6GPM (gallon per minute) in warm places like the southern United States.
  • Saves space 90% smaller than the ordinary tank water heater.


We have tried our best to provide you with the exact cause and solutions of Why is tankless water heater is beeping?

If you are still unable to solve the problem or need further assistance, don’t forget to leave us a comment below. We always welcome your feedback!

About Zarmish Fakhar

Zarmish has been working as a freelance research writer for 5 years. She is a Zoologist and social media activist as well. She has worked for many reputable newspapers including Dawn. She is a valuable member of Aqua macho as her passion for clean water and eco-friendly products are booming day by day.

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