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How to Reset a Tankless Water Heater? – Detailed Tutorial

Fact checked by Stephen Conklin

how to reset a tankless water heater

Did your tankless water heater stop giving you hot showers and hot water for your dishwasher and other needs? Are you planning to flush your system to get rid of sediments and other impurities in the coils? Addressing these concerns is a cinch if you know how to reset a tankless water heater.

The good news is tankless water heaters are more straightforward to reset than conventional tank water heater systems. These appliances have a dedicated button for resetting the unit without removing anything else.

Join me in learning the easy four-step process for resetting a tankless water heater.

Table of Contents

Things You Will Need for This Guide


Resetting a tankless water heater is not as complicated as you might think. After all, this water heating device is smaller and more compact than your conventional tank water heater. Looking for its reset mechanism should be a breeze.

However, you can make the process more straightforward by preparing the following things.

User Guide

It would be wise never to underestimate the value of a model-specific user guide or owner’s manual. Not only does it contain detailed instructions on where to locate the device’s reset button, but the user guide also explains the correct reset procedure for the model.

Unfortunately, some of us may have already misplaced our user guide. Never fret because the internet is here to help. You can find downloadable user guides in PDF format specific to your brand and model of the tankless water heater.

Community forums are also excellent sources of information. You only need to post a question and members can give you the answer you need.

Understanding of the Need for Resetting a Tankless Water Heater

There are many reasons for resetting a tankless water heater. Resetting this appliance is always a crucial step in flushing the unit.

Flushing allows you to remove sediments, limescale, hard mineral deposits, and other particles present on the inside of the tankless water heater’s heating elements and other components. Resetting the water heater after flushing restores it to its factory default settings.

Resetting a tankless water heater is also necessary when fixing errors. While modern tankless water heaters are easy to use, troubleshooting can be challenging for some people.

Pressing the reset button is always easier than going through the various troubleshooting steps and procedures.

However, if your tankless water heater requires frequent resetting, it might be time to have a professional check on your unit. It might have a problem worth investigating further, necessitating a more permanent fix than simply resetting the water heater.

Steps for Resetting a Tankless Water Heater


Step 1. Cut off the power to the tankless water heater.

Tankless water heater manufacturers recommend switching off the appliance’s power before working with its electrical components. If you’re unsure, I recommend checking the tankless water heater user guide for model-specific instructions.

Installing tankless water heaters requires hardwiring the system to a dedicated circuit breaker. Ideally, the water heater circuit breaker should have a label, avoiding the hassle of turning off the whole circuit breaker panel.

Check your breaker panel and look for the circuit breaker that regulates electricity to the tankless water heater. Turn this circuit breaker to the OFF position.

Step 2. Locate the tankless water heater’s reset button.

Companies integrate their tankless water heater reset button at different locations. That is why it would be best to read your user guide to determine the reset button’s precise location.

If you no longer have a copy of the owner’s manual, you can try searching and downloading it online. Most manufacturers provide downloadable PDF files of their user guides.

Alternatively, you can ask for online community forums. Some members might have the same tankless water heater, and they can advise you where to check the reset mechanism.

Most tankless water heaters have the reset button at the unit’s front or side. In most cases, it is on the control panel.

Since tankless water heaters are compact, you can easily locate a red button with a ‘reset’ label.

Step 3. Press the reset button.

The next step involves pressing the reset button. It would be wise to observe patience because it might take some time before the device resets.

In some situations, it might be challenging to press the button because it is sticky. This often occurs in rarely-reset tankless water heaters.

Try to listen for a click, indicating a successful tankless water heater reset.

RV_Dude has an excellent video on resetting a tankless water heater. Although the video talks about an RV water heater, the process is almost similar to resetting a tankless water heater for the home.

Step 4. Reestablish power to the tankless water heater.

Turn on the tankless water heater circuit breaker and run the appliance for several minutes. If all goes well, you should have hot water within ten minutes or less.

Unfortunately, if the reset button trips again, it would be wise to have an expert assess the situation. In that case, it is always best to turn off the tankless water heater’s circuit breaker again until a water heater technician identifies the problem.

Some Notes on Resetting Specific Tankless Water Heater Brands

The steps we outlined above may or may not apply to your tankless water heater brand. That is why I always recommend checking the manufacturer’s user guide for more detailed model-specific instructions.

Nevertheless, here are a few modifications to the reset procedure of select tankless water heater brands.

Rinnai Tankless Water Heaters

Rinnai tankless water heaters always display an error code on their control panel or module. The error code can range from 02 to 79. It can also include non-numeric data, such as LC, FF, LC-LC, and No Error Code. Resetting the unit erases these error codes and returns the appliance to the default settings.

To reset a Rinnai tankless water heater, you can check the ‘Control-R’ module. It resets the tankless water heater to its factory defaults.

Locate the Connect button on the module and press and hold it until the blinking LED light turns white. You can release the Connect button by then.

Marey Tankless Water Heaters

If you want to reset Marey tankless water heater, it is essential to cut off the appliance’s power supply at the circuit breaker. You can then press the reset mechanism until it clicks. Once reset, you can restore power to the tankless water heater.

Noritz Tankless Water Heaters

You can reset a Noritz tankless water heater by pressing the reset button located on the device’s front panel. We often do this as a more straightforward fix to various error codes on the machine.


Learning how to reset a tankless water heater does not take more than pressing a red button marked ‘reset,’ although some brands might require you to switch off the tankless water heater’s circuit breaker first.

I hope you feel more comfortable addressing any issues with your tankless water heater. While resetting the device can fix nagging problems, I still recommend calling a professional if they persist.

What do you think? Did I miss anything? You can shoot me any concerns or questions you have about this tutorial. I would also appreciate it if you could share this guide with your friends.

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