Flushing The Heat Exchanger - Rinnai RUR98i Installation And Operation Manual

Flushing the Heat Exchanger

An LC0~LC9 or "00" or 58 diagnostic 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. Rinnai strongly recommends installation of isolation valves to allow for flushing of the
heat exchanger.
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 4 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. Operate the pump and allow the vinegar to circulate
through the water heater for at least 1 hour at a rate
of 4 gallons per minute (15.1 liters per minute).
9. Turn off the pump.
10. Rinse the vinegar from the water heater as follows:
a. Remove the free end of the drain hose (H3) from
the pail. Place in sink or outside to 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
10 minutes.
d. Close shutoff valve (V4). When unit has finished
draining remove the in-line filters at the cold
water inlet and the hot water outlet and clean out
any residue. Place filter back into unit and open
valve (V4).
e. Close service valve, (V1), and open shutoff valve,
(V3).
11. Disconnect all hose
12. Restore electrical power to the
water heater.
Following flush procedure call
technical assistance (1-800-621-
)
9419 for PCB reset information.
70
3/4" Ball Valve
3/4" Union
Check Valve
Pressure Relief Valve
H3
H2
Circulating Pump
KBP Series Manual
KEY
Pressure Regulator
Circulating Pump
Boiler Drain Valve
S
Solenoid Valve
Rinnai
Water Heater
V2
V1
V4
V3
H1