Rinnai RUC80i Training Program page 79

Maintenance:
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PROPRIETARY and CONFIDENTIAL
Heat exchanger flush procedure.
For proper operation, unit longevity, and warranty adherence, water supply to the water
heater must meet National Secondary Drinking Water Regulations. In areas with hard
water, a water softener or other conditioning may be needed. A periodic flushing
procedure may also be required. Below is the proper flushing procedure:
1. Disconnect electrical power to the water heater, Disconnect from MSA, MSB , or E-Z connect cables
from unit (if applicable).
2. Close the shutoff valves on both the hot 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 service valve V1
5. Pour approximately 4 gallons of virgin food grade white vinegar or citric acid into pail
6. Place the drain hose (H3) and the hose (H2) to the pump inlet into the cleaning solution
7. Reconnect power to unit and allow Water flow servo and Water flow by-pass time to reset to start
position, approximately 10-15 seconds. Disconnect power again before flushing.
8. Open both service valves (V1 and V2) on the hot and cold water lines
9. Operate the pump and allow the cleaning solution to circulate through the water heater for at least
45 minutes
10. Turn off the pump
11. Rinse the cleaning solution from the water heater by:
12. Disconnect all hoses
13. Remove the in-line filter at the cold water inlet and clean out any residue
14. Open shutoff valves V3 and V4.
15. Restore electrical power to the water heater.
Enhancing Lives By Changing The Way Water Is Heated
a. Remove the free end of the drain hose (H3) from the pail and place in a suitable drain
b. Close service valve, V2, and open shutoff valve, V4. Do not open shutoff valve, V3.
c. Allow water to flow through the water heater for 5 minutes
d. Close service valve, V1 and shutoff valve V4.
a. Place the filter back into the unit.
79 5/4/2018