Rinnai RH180 Operation And Installation Manual page 40

Use the following procedure to flush the heat exchanger of lime or scale build up. Damage caused by lime build-
up is not covered by the unit's warranty. A er flushing, reset any error codes 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 cold water supply valve. Leave the hot water valve and a hot water fixture OPEN to remove pressure
from the system.
3.Connect one end of a hose to the drain valve on the tank and direct the other end to a drain. OPEN the drain valve.
4.Remove the (3/4" NPT) flex fi ngs
approximately 1/2 gallon of water. Prepare a bucket to catch this water.)
5.Connect pump outlet hose (H1) to the (3/4" NPT) in-line filter fi ng at the base of the engine.
6.Connect drain hose (H3) to the (3/4" NPT) supply fi ng at the base of the engine.
7.Pour approximately 4 gallons of virgin, food grade, white vinegar or citric acid into a pail.
8.Place the drain hose (H3) and the hose (H2) to the pump inlet into the cleaning solu on.
9.Operate the pump and allow the cleaning solu on to circulate through the water heater for at least 45 minutes.
10.Turn off pump.
11.Rinse the cleaning solu on from the water
heater as follows:
a. Disconnect hose (H1) from the engine.
b. Connect a cold water supply fi ng and hose
to the IN-LINE FILTER fi ng at the base of
the engine (3/4" NPT).
c. Move drain hose (H3) from the pail to a
drain.
d. Open cold water supply and allow water to
flow through the engine for 5 minutes.
e. Remove, clean and replace the in-line filter.
f. Remove Hose (H3) and the cold water sup-
ply hose from the base of the engine.
g. Re-Install the (3/4" NPT) flex fi ngs
2
to the assembly.
h. CLOSE THE DRAIN VALVE
i. Open the cold water supply valve un l wa-
ter flows from the hot water fixture
j. Close the cold water supply valve.
k. Connect power to the water heater and
turn the temperature down to set point 1.
12.Open the cold water supply valve un l water
flows from the hot water fixture (See Step
2).
13.Close the hot water fixture and inspect
the appliance and plumbing for leaks.
40
Hybrid Tank-Tankless Flush Procedure
Do not con nue un l all water has drained from the tank.
NOTICE
1
2
and
1
and
from the assembly. (Note: The tankless unit will s ll contain
IN-LINE FIL-
TER
5 gallon pail of virgin,
food grade, white
vinegar (or virgin,
food grade, citric
PUMP
H2
DRAIN
RH180 Manual
HOT WA-
TER
VALVE
1
H1
H3
COLD
WATER-
SUPPLY
VALVE
2