Rinnai HE Series How To Use Manual page 180

1. Check sensor wiring harness for loose, broken or damaged connections from sensor back to PC
board.
2. This code indicates a scale build‐up inside the secondary heat exchanger and it needs to be
flushed to prevent damage. Refer to flushing instructions in the owner manual. Hard water must
be treated to prevent scales build‐up or damage to the heat exchanger will occur.
Code 58 Troubleshooting Procedure
Secondary Heat Exchanger Sensor
28