Installation Guide

Rinnai Tankless Water Heater Installation and Operation Manual 87
A
………B
This water heater includes a service indicator/reminder (Service Soon,
SS
). When selected in the
parameter settings, an
SS
code will display on the controller indicating that it is time to flush and
service the water heater. An LC diagnostic code also indicates the unit is beginning to lime/scale up
and must be flushed. Failure to flush the appliance will cause damage to the heat exchanger.
Damage caused by lime/scale build-up is not covered by the water heater’s warranty. Rinnai strongly
recommends installation of isolation valves to allow for flushing of the heat exchanger.
1. Shut off gas supply and turn off the controller.
2. Close the shutoff valves on both the hot water and cold water lines (V3 and V4).
3. Connect pump outlet hose (H1) to the cold water line at service valve (V2).
4. Connect drain hose (H3) to the hot water line at service valve (V1).
5. Pour four gallons of undiluted virgin, food grade, white vinegar into pail.
6. Place the drain hose (H3) and the hose (H2) to the pump inlet into the cleaning solution.
7. Open both service valves (V1 and V2) on the hot water and cold water lines.
8. Remove the water heater front panel by removing two screws and releasing two latches.
9. Locate the PC Board at lower of unit (Figure 95).
10. Locate the push buttons (A and B) on the PC board.
11. Press the “B” button for 1 second and release when display shows “dES” (descaling). Push the
“A” button. “dES” starts blinking.
Figure 94
Figure 95
Figure 96
dES