Noritz ecoTOUGH NRC71 OD Installation Manual page 15

Procedure for Flushing the Heat Exchanger
This procedure is only intended for use by a qualified service professional or authorized Noritz
Service Representative. Any unauthorized use of this procedure may result in voiding the
warranty.Please contact Noritz America (866-766-7489) for additional support.
If the error code "C #*~C #*" is flashing on the Display Window, it means there is Scale Build-up
in the Heat Exchanger.The Heat Exchanger needs to be flushed** to remove the Scale Build-up.
Damage to the water heater due to Scale Build-up is not covered by the water heater's warranty.
To clear the error code "C #*~C #*", the Heat Exchanger must be flushed.
If the error code "C #*" is displayed and flashing in the Display Window, please contact Noritz
America (866-766-7489).
** Connect the blue connector marked "FLUSH" for flushing on the Circuit Board when flushing the Heat Exchanger.
After connecting it, the water heater is set to "Flushing Mode".
1. Close the gas supply valve.
2. Close the water inlet valve (V1) and the water outlet valve (V2).
3. Connect the one drain hose (H1) to the drain valve (V3), and then the other to the circulating
pump.
4. Connect the drain hose (H2) to the circulating pump.
5. Connect the drain hose (H3) to the drain valve (V4).
6. Pour 1 gallon of "Calcium, Lime and Rest Removal Product"*** and 1 gallon water into the bucket.
***Notriz recommends "Calcium, Lime and Rest Removal Product" for flushing.
7. Place the both drain hoses (H2 and H3) into the bucket filled with the flushing solution.
8. Open the both drain valves (V3 and V4).
from an authorized Noritz wholesaler.
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