Flushing The Heat Exchanger - Rinnai REU-VA2019FFUD-UC Operation And Installation Manual

Flushing the Heat Exchanger (Error Code: LC or 00)
An "LC" or "00" error code indicates the unit is beginning to lime up and must be flushed. Failure to flush the
appliance will cause damage to the heat exchanger. Damage caused by lime build-up is not covered by the unit's
warranty. After flushing, reset the LC fault code by turning off the power to the unit and turning the power back
on.
1. Disconnect electrical power to the water heater.
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 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. Open both service valves (V1 and V2) on the hot water and
cold water lines.
8. Operate the pump and allow the cleaning solution to
circulate through the water heater for at least 45 minutes.
9. Turn off the pump.
10. Rinse the cleaning solution from the water heater as follows:
a. Remove the free end of the drain hose (H3) from the pail.
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 open shutoff valve, (V3).
11. Disconnect all hoses.
12. With (V4) closed, remove the in-line filter at the cold water
inlet and clean out any residue. Place filter back into unit
and open (V4).
13. Restore electrical power to the water heater.
5 gallon pail of virgin, food
grade, white vinegar (or virgin,
food grade, citric acid).
3/4" Ball Valve
3/4" Union
Check Valve
Pressure Relief Valve
16
KEY
Pressure Regulator
Circulating Pump
Boiler Drain Valve
S
Solenoid Valve
VA Series Indoor LS Manual
V1
H3
H2
Circulating Pump
Rinnai
Water Heater
V2
V4
V3
H1