Rinnai Master Reset

1. Press and hold A and B until P appears (approximately 10 seconds)
2. Press and hold A and B until "PCL" appears (approximately 10 seconds)
3. The unit will power off 
4. Press the power button until the unit powers back up.

This is how to perform a master reset on the RINNAI

The A and B buttons are located in the Panel and not the on the actual screen