Rinnai Tankless Water Heater Reset Button

Rinnai Tankless Water Heater Reset Button [The Ultimate Guide]

This is a complete guide on Rinnai Tankless Water Heater Reset Button. In this article, I will break down these two questions: 

  • Does a Rinnai tankless water heater have a reset button?
  • How to reset a Rinnai tankless hot water heater? 

So, stay in tune with me till the end to discover the answer.  

Disclaimer: The resetting methods I will describe work for the RL75 model. However, I hope it will also work for other models as well. 

Table of Contents

Does A Rinnai Tankless Water Heater Have A Reset Button?

Unfortunately, the Rinnai Tankless Water Heater doesn’t have a reset button. I checked the manual of the Rinnai tankless unit but I didn’t find anything about the reset button. 

However, it doesn’t mean you can’t reset the Rinnai tankless water heater. You can use the on/off button to reset the unit. It’s located at the top of the unit. 

If the on/off button doesn’t bring any luck to you, you should use the A/B buttons. You can find these two buttons near the PC board. To access these buttons, you must remove the front panel by unscrewing the four nuts that hold it in place. 

And here how the A and B button looks like: 

rinnai A and B buttons

In the ‘How To Reset’ section, I will show how exactly you can use the power button and the A & B buttons to reset your Rinnai tankless hot water heater. So, keep reading.

How To Reset Rinnai Tankless Water Heater?

Resetting a Rinnai tankless water heater is not as challenging as you assume. Below, I will describe two methods to reset the tankless water heater. 

Method 1. Use the On/Off Button: 

  • Locate the on/off button on the temperature controller of the unit. 
  • Now, press the on/off button five times in 5 seconds. 
  • And it will reset your water heater and clear the error message. 

Keep in mind; this method works only when the temperature controller showcases the error code 55. 

Method 2. Pressing the A and B buttons: 

This is a standard method to reset your tankless water heater. Follow the below steps to learn how to use the A and B buttons to reset the unit: 

  • Remove the front panel of the unit by unscrewing the four nuts.
  • Locate the PC board and you can find two buttons there. 
  • Then, unscrew the plastic panel to access the A and B buttons. 
  • Press and hold the two buttons simultaneously for five to eight seconds, and it will reset the unit. 
  • Lastly, replace the front panel back into its place. 

Note: In some cases, the display may change to P when you hold down the A and B buttons. If this happens to you, press and hold both buttons a second time. It will turn the display into PCL and reset the unit. 

Apart from these two methods, you can also clear the fault code by resetting the main power supply to the unit. 


Why does my tankless water heater go cold in the middle of a shower?

If the heat exchanger of the unit gets damaged, your tankless water heater will go cold in the middle of a shower.

Does the Rinnai tankless water heater have a pilot?

No, the Rinnai tankless water heater doesn’t have a pilot. It comes with an ignition device, which automatically ignites the burner.

How to reignite your Rinnai tankless water heater?

Go with the follow steps to igniter your tankless water heater: 

  • Set the water temperature to the lowest setting.
  • Shut off all the electric power to the unit. 
  • Turn the manual gas control valve clockwise to the off position. 
  • Leave the unit for five minutes to let all the gas clear out. 
  • Turn the manual gas control valve counterclockwise to the on position. 
  • Turn the electric power to the unit. 
  • Set the water temperature to your desired setting and it will ignite the unit and start heating water.

Does the Rinnai tankless water heater have an air filter?

Yes, the Rinnai tankless water heater has an air filter and it’s located at the top right corner of the unit.


Though there is no reset button on Rinnai tankless water heater, you can still reset the unit. Its on/off button and A & B buttons meet the purpose of a reset button. Just follow the methods I mentioned above and reset your tankless unit successfully. Don’t forget to leave a comment below if you have any questions to ask.

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