Flushing The Heat Exchanger (Error Code: Lc Or 00); Clean Thermistors - Rinnai RL75I 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 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 cleaning solution
to circulate through the water heater for 1 hour at
a rate of 4 gallons per minute (15.1 liters per
minute).
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.

CLEAN THERMISTORS

Remove and clean thermistors
with a soft cloth or sponge after
removing O-rings.
Cleaning solution is 4 gallons of
undiluted virgin, food grade,
white vinegar.
H3
H2
Circulating Pump
VB Series Indoor LS Manual
KEY
3/4" Ball Valve
3/4" Union
Check Valve
Pressure Relief Valve
Rinnai
Water Heater
V2
V1
V3
H1
Pressure Regulator
Circulating Pump
Boiler Drain Valve
S
Solenoid Valve
V4
15