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how to reset tankless water heater

How to Reset Tankless Water Heater: Easy Step By Step Guide

If your tankless water heater doesn’t appear to be working properly, don’t panic just yet. The easiest possible solution could be resetting it. In this guide, we’ll discuss how to reset a tankless water heater.

For homeowners who require further support, American Home Water & Air can repair or even carry a new tankless water heater installation in Phoenix if it comes down to it. Either way, we’re here to help you solve the problem and make sure that your tankless water heater is back up and running.

Here’s what you need to know to reset a tankless water heater.

Step 1: Disconnect the Tankless Water Heater

Disconnect the tankless water heater from electricity. Disconnecting the tankless water heater is a safety measure. Ensure there is no electricity going to the heater when you inspect the unit. Look around the unit for the cable that connects the unit to a power source.

An older tankless water heater will be attached to the breaker box. If the tankless water heater is attached to the breaker box, flip the switch to OFF. This way, you ensure there is no power going to the tankless water heater.

You can proceed when the tankless water heater is disconnected from the power source.

Step 2: Find and Remove Cover Plate

Older models of tankless water heaters will have cover plates. Remove the cover plate with a Phillips or flathead screwdriver.

The cover plate sits on the front of the unit to protect the interior from the exterior. Once you locate the cover plate, you will see at least two screws keeping it in place. Remove the screws and the cover plate and set them aside. You will reattach the cover plate later.

If there is no cover plate, continue to the next step.

Step 3: Take Out Insulation

When you remove the cover plate, you are likely to find insulation. Insulation acts as another barrier between the cover plate and the water heating unit. Remove the insulation from the tankless water heater. 

Inspect the insulation for any signs of moisture. Any signs of moisture can be indicative of other problems. If there is moisture, contact your plumber for advice.

If there is no insulation, continue to the next step. You can contact your plumber if insulation is something you want to add to your system.

Step 4: Locate the Reset Button

The tankless water heater reset button is located on the front or right side. The good news is that pretty much all of them have this button. If you cannot find the reset button on the front or right side, look at the back of the machine.

If you cannot find the reset button, call customer service. The manufacturer of the tankless water system can help you find the reset button. 

When you locate the reset button, you can press it.

Step 5: Ensure the Tankless Water Heater is in Reset Mode

After you locate and press the reset button, ensure your tankless water heater is in reset mode. Reset mode is crucial because it enables the tankless water system to restart existing processes. In reset mode, the internal processes will restart and reboot. An effective reset is key to getting the tankless water heater working.

You will see a light on the tankless water heater. If the light on the tankless water heater goes from red to green, you are successful. After the light changes from red to green, wait ten seconds before proceeding to the next step. 

Do not forget to wait ten seconds—this gives your tankless water heater time to reset.

Call your plumber for further assistance if the light does not go from red to green. There may be a larger problem at hand that your plumber can fix.

Step 6: Change the Thermostat

The thermostat on the tankless water heater will vary depending upon the model. Most tankless water heaters have a knob. The knob changes the temperature of the thermostat.

Locate the knob on the thermostat and turn it clockwise. Turn the knob as far clockwise as it will go. Once the knob is all the way clockwise, this indicates a maximum setting.

Again do not forget to wait ten seconds. When you wait ten seconds, your tankless water heater has time to reset.

Step 7: Check for Power Outages in the Home

The tankless water heater could be representing a larger power issue. Check for other power outages in your home. You could be having electrical problems that have only manifested in the tankless water heater.

Check the breaker system and see if any switches are in the wrong position. Flip any switches to restore electricity to all units. 

If the above steps do not work, it is time to call your plumber. Your plumber knows of common issues that tankless water heaters face, and as a result, they are in a unique position to help with the problem. 


A tankless water system is an essential component of your home. Sometimes, water unexpectedly runs cold. A tankless water heater does not store water, so these problems often are indicative of a unit issue. Knowledge of how to reset a tankless water heater will make life easier. You can also check out our other guide if you’re looking for more information on how to troubleshoot your tankless water heater.

Hopefully, these seven steps for how to reset a tankless water heater have helped fix the issue. If you have tried using this process and nothing is working, your next step is calling us. American Home Water & Air is your go-to plumbing service in Arizona that will take the next steps to fix the problem.

Contact us today for more information.

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