Rinnai RL75I, RL94I Flushing the Heat Exchanger Error Code LC or, Circulating Pump

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.

KEY

3/4" Ball Valve	Pressure Regulator
3/4" Union	Circulating Pump
Check Valve	Boiler Drain Valve
Pressure Relief Valve	S Solenoid Valve

Rinnai

Water Heater

In-line

Filter

V1 V2

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	V3	V4
	Hot	Cold	Gas
			Supply
	Water
		Water
	Line
		Line

H2

H1

Circulating Pump

VB Series Indoor LS Manual 15