Learning how to reset a tankless water heater is a quick and easy way to fix many common problems you may be experiencing. In this step-by-step guide, we’ll go over how you can reset your Rinnai, Rheem, or Navien tankless water heater.

Why Would a Tankless Water Heater Need to be Reset?

A tankless water heater may need to be reset if:

• You recently had a power outage
• You aren’t getting any hot water
• Your tankless is overheating
• To reset any programmable thermostat settings
• To clear any error codes

Resetting your tankless won’t fix every problem, but it’s a good first step you can take to figure out if there’s a larger issue going on that would require professional help.

Let’s start by going over how to reset a Rinnai tankless water heater.

How to Reset a Rinnai Tankless Water Heater

Rinnai tankless water heaters don't have a reset button, so you'll have to do this manually. The steps for resetting a Rinnai tankless water heater will vary depending on whether you have an indoor or outdoor model.

How to Reset an Interior Rinnai Tankless Water Heater

Step 1: Unplug the tankless from the outlet.

Step 2: Wait 10-15 seconds.

Step 3: Plug the unit back in and wait. During this time, the unit will start its restart process.

How to Reset an Exterior Rinnai Tankless Water Heater

Step 1: Locate the on/off switch next to the tankless.

Step 2: Open the cover and flip the switch to the off position.

Step 2: Wait 10-15 seconds and switch the unit back on.

*Note - Once you plug your unit in or turn the switch back on, you’ll begin to hear noises that closely resemble the way dial-up internet used to sound when starting. This is normal. Just wait for it to go through its startup cycle.

You can also reset your Rinnai water heater by turning the breaker off at your circuit box. To do this, find the breaker that corresponds to your Rinnai water heater and turn it off. Wait 20-30 seconds, and then turn the breaker back on.

There may also be times when you’ll need to reset your Rinnai back to its factory settings. This is typically done to clear any error codes or after any maintenance that’s been done.

How to Reset a Rinnai Tankless Water Heater Back to Factory Settings

To reset a Rinnai tankless water heater back to its factory settings, you can follow these steps:

Step 1: As a safety measure, turn off the power to your tankless water heater.

Step 2: Unscrew and remove the cover.

Step 3: Once the cover is removed, locate the PC board on the bottom right of the unit.

Step 4: Find the two black A and B buttons on the PC board.

Step 5: Press and hold these buttons for 5-10 seconds until you see a “P” displayed on the control panel. Once displayed, release the buttons.

Step 6: Press and hold the two buttons again until “PCL” is displayed. Once displayed, release the buttons, and your Rinnai will begin the reset process.

How to Reset a Navien Tankless Water Heater

To reset a Navien tankless water heater, follow these steps:

Step 1: Locate the reset button on the front display panel. On newer models, this will be the button with the return arrow on it.

Step 2: Press and hold the reset button for 5-10 seconds or until you hear a beep. This indicates that the reset process has started.

Step 3: Allow the unit to go through its reset process.

Step 4: Check to make sure your temperature settings are the same.

How to Reset a Rheem Tankless Water Heater

To reset a Rheem tankless water heater, follow these steps:

Step 1: Turn the gas valve to the off position.

Step 2: Turn the incoming water line to the off position.

Step 3: Unscrew the four screws on the front panel cover and remove it.

Step 4: Locate the PC board inside the tankless.

Step 5: Look for the two sets of dip switches and the two buttons underneath that say min and max.

Step 6: On the set of switches labeled "DIP switch 1", move switch 2 up and down within 5 seconds.

Step 7: Immediately after you flip this switch up and down, press and hold both the min and max buttons for at least 7 seconds. On the display screen, you should see a "UL" code flashing.

Step 8: Hold these buttons until the "UL" code turns solid or disappears.

Step 9: Once you see a solid "UL" code or it disappears, press the power button to turn your Rheem tankless back on. Once on, you should see the temperature showing on the display screen.

Step 10: Turn the gas and water valves back on and run hot water to make sure everything is working as normal.

By following the steps above, you should now be able to reset your Rinnai, Navien, or Rheem tankless water heater. If you’re unable to reset your tankless water heater using these steps, you may need to contact a qualified technician for assistance.

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