Rheem 874W27NF User manual

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SERVICE INSTRUCTIONS
Rheem 27 Water Star
Continuous Flow Water Heater with Auxiliary Hot
Water Storage Tank
TM061
First Issued: Nov 10
Revision A
Issued: Aug 13
Rheem
874W27

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
REV A Issued 08/13
This document is stored and maintained electronically by Service. All printed copies not bearing this statement in RED are deemed “uncontrolled”
CONTENTS
INTRODUCTION .................................................................................................................3
SAFETY WARNING.............................................................................................................3
WATER HEATER MODEL IDENTIFICATION.....................................................................4
SPECIFICATIONS...............................................................................................................5
WIRING DIAGRAM..............................................................................................................6
PRESET TEMPERATURE ADJUSTMENT .........................................................................7
SEQUENCE OF OPERATION.............................................................................................8
BYPASS OPERATION ........................................................................................................9
ANTI-FROST HEATER CIRCUIT ........................................................................................9
COMPONENTS AND THEIR FUNCTION .........................................................................10
IN-SERIES GAS BOOSTING ............................................................................................12
REMOTE TEMPERATURE CONTROLLERS....................................................................12
EZ-LINK™SYSTEM..........................................................................................................12
TEMPERING VALVES.......................................................................................................12
MAINTENANCE INFORMATION.......................................................................................13
OPERATIONAL FLOW CHARTS ......................................................................................16
ERROR CODES................................................................................................................19
THERMISTOR RESISTANCE CHART..............................................................................22
FAULT FINDING................................................................................................................22
FAULT DIAGNOSIS SEQUENCE .....................................................................................23
POWER SUPPLY FAULT-FINDING..................................................................................24
NO ERROR CODE FAULT FINDING................................................................................26
Error Code 11....................................................................................................................28
Error Code 12....................................................................................................................32
Error Code 14....................................................................................................................33
Error Code 15....................................................................................................................33
Error Code 16....................................................................................................................34
Error Code 24....................................................................................................................35
Error Code 29....................................................................................................................35
Error Code 31, 32, 33 & 34................................................................................................36
Error Code 35....................................................................................................................36
Error Code 51....................................................................................................................37
Error Code 52....................................................................................................................38
Error Code 61....................................................................................................................38
Error Code 65....................................................................................................................39
Error Code 66....................................................................................................................39
Error Code 71....................................................................................................................41
Error Code 72....................................................................................................................41
Error Code 76....................................................................................................................41
Error Code 79....................................................................................................................42
Error Code 80....................................................................................................................42
Error Code 82....................................................................................................................43
Error Code 99....................................................................................................................44
Warning Code....................................................................................................................44
WATER SAVING FAULT FINDING ...................................................................................45
BURNER GAS PRESSURE CHECK.................................................................................48
COMPONENT REPLACEMENT PROCEDURE................................................................49
DOCUMENT REVISION HISTORY...................................................................................61

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
REV A Issued 08/13
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INTRODUCTION
The information provided in these service instructions is based on the water heater being
installed in accordance with AS/NZS 5601 and the Installation Instructions provided with
each water heater.
Should you require further technical advice on any Rheem Water Heater, contact your
nearest Rheem Service Department where genuine replacement parts are also available.
SAFETY WARNING
The purpose of this service manual is to provide sufficient information to allow a person with
the skills as required by the Regulatory Authorities to carry out effective repairs to a
continuous flow gas water heater with an electric boosted auxiliary hot water storage tank in
the minimum of time.
Safety precautions or areas where extra care should be observed when conducting tests
outlined in this service manual are indicated by print in bold italics and/or a warning symbol.
Take care to observe the recommended procedure.
“Live” testing to be conducted. Personal Protective Clothing (PPE) shall be
worn and an RCD shall be installed between the power point and 3-pin cord
of the water heater to reduce the risk of electric shock.
Isolate power before conducting the indicated test.
Hot surface or liquid. Personal Protective Clothing (PPE) shall be worn to
reduce the risk of scalding.
General warning symbol. Observe the instructions accompanying the
symbol.
If the supply cord is damaged, it must be replaced by the manufacturer or
its service agent or a similarly qualified person in order to avoid a hazard.
When conducting repairs to a gas appliance the gas train including injector
sizes must not be altered or modified in any way.

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
REV A Issued 08/13
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WATER HEATER MODEL IDENTIFICATION
The identification numbers are designed to convey detailed information about the water
heater to which it is attached. The model number consists of 6 digits and up to 3 letters.
87
4
W
27
N
F
Brand
87 –Rheem External
Temperature Setting
4 - 60ºC Set temperature
W –Water Star
Capacity
27 –27L/minute @ 25 ºC rise
Gas Type
N –Natural Gas
P –Propane
F –Frost protection fitted
The model number, serial number and date of manufacture should be quoted in all correspondence.

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
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SPECIFICATIONS
Model
874W27NF
874W27PF
Gas Input (MJ/hr)
205
Output (kW)
46
Installation
Wall Mounting
Mass (kg)
29
Min Water Pressure (kPa)
140
Max Water Pressure (kPa)
800
Min Water Flow (L/M)
2.0
Max Flow Rate @ 25°C Rise (L/M)
27
Max Flow Rate @ 40°C Rise (L/M)
16.5
Gas/Water Connections
R¾/20
Injector Orifice (qty x dia mm)
16 x 2.05
16 x 1.25
Burner Test Point Pressure (kPa)
Min
0.193
0.277
Max
0.905
1.430
Min Inlet Gas Pressure (kPa)
1.13
2.75
Max Inlet Gas Pressure (kPa)
3.5
Storage Tank Relief Valve Setting (kPa)
1000
Heater Relief Valve Setting (kPa)
1750
Power Consumption
Gas CF(1)
175W
Water Star(2)
500W
Electrical
Rating
240 VAC/50Hz, 3 Amps
Fuse
2 x 5A Fuse (line voltage), 5A fuse on power supply PCB
Safety Devices
Over Heat Limiter for Heat Exchanger
Heat Exchanger Thermistor (Boiling Point Safety)
T&PR Valve (HT55 1000kPa)
Freeze Protection
-20°C (Without Wind-Chill Factor) with power applied
Controllers
N/A
(1) Maximum power consumption with heater running and anti-frost heaters energized.
(2) Maximum power consumption with element operating.

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
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WIRING DIAGRAM
A wiring diagram is also located on the inside of the front cover panel.

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
REV A Issued 08/13
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PRESET TEMPERATURE ADJUSTMENT
The water heater has a factory preset outlet temperature setting of 60°C however the Water
Star water saving function within the heater has a set point of 70°C (a quantity of water is
maintained within the cylinder at a fixed temperature, and water initially discharged by this
heater at start-up may be at a temperature of up to 70°C before the heater normalises to its
preset outlet temperature).
Voltages up to 240 volts will be present within the water heater, take care
not to touch wiring terminals. Use an insulated tool when operating the DIP
switch or MIN and MAX buttons.
To check or adjust the preset outlet temperature setting:
1. Remove the front cover from the water heater.
2. Switch dip switches 3 and 4 to the ON (up) position on the DIP1 set of dip switches on
the PCB.
3. The current preset outlet temperature setting will be displayed on the LED1 display at
bottom right hand side of water heater.
4. Press the MIN button to decrease or the MAX button to increase the preset outlet
temperature setting to the desired setting. (The MIN and MAX buttons are located below
the dip switches.)
5. Turn dip switches 3 and 4 to the OFF (down) position on the DIP1 set of dip switches on
the PCB.
6. The LED1 display will go blank. The preset outlet temperature is now set.
7. Refit the front cover to the water heater.
The preset outlet temperature settings are: 38°C, 40°C, 42°C, 43°C, 45°C, 50°C, 55°C,
60°C, 70°C and 75°C.
Notes: Setting the outlet temperature to less than 50°C IS NOT RECOMMENDED; if the
temperature is adjusted to less than 50°C the water saving function of the water heater will
not operate, resulting in added energy costs and nil water saving.

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
REV A Issued 08/13
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SEQUENCE OF OPERATION
Refer to „Sequence of Operation Component Diagram‟ on page 9 to view components
shown in brackets e.g. (1)
1. When a hot water tap (1) is opened, cold water enters the water heater and passes
through the Water Flow Sensor (4),Heat Exchanger (20) and Transfer Pipe. A
temperature actuated Transfer Valve (28)located at the outlet of the transfer pipe
determines where to direct the water flow depending on the water temperature.When the
temperature of the water entering the transfer valve is below 42ºC the transfer valve will
direct water flow through the auxiliary hot water storage tank (29)and hot water stored at
70ºC is delivered to the hot tap from the auxiliary hot water storage tank.
2. As water flows through the unit it induces movement in the Water Flow Sensor (4) which
sends a pulse signal to the PCB (8). Once the pulse signal reaches a pre designated
frequency (at a min. flow rate of 2lpm) the PCB (8) activates the Fan Motor (26) and the
Fan (25) starts rotating.
3. After the Fan (25) completes a pre purge to ensure the vent is clear, the Proportional Gas
Flow Regulator (14) allows gas to flow to the Burner (16).At the same time the Igniter
(17) starts sparking continuously and ignites the gas at the Burner (16).
4. Hot water delivery from the auxiliary hot water storage tank will continue until the gas
heater has achieved ignition and the water being delivered from the gas heater reaches a
temperature above 42ºC at which point the transfer valve (28) will gradually bypass the
auxiliary hot water storage tank and hot water will be delivered directly from the gas
heater to the hot tap (1).
5. After ignition the Flame Rod (19) monitors the burner flame. The PCB (8) constantly
monitors all inputs to ensure the outlet water temperature is maintained within 1oC of the
thermostat setting. The Proportional Gas Flow Regulator (14) continuously adjusts the
gas volume and the water flow is also adjusted to assist in supplying a stable hot water
temperature at all times.
6. As the gas flow rate, controlled by the Proportional Gas Flow Regulating Valve (14)
changes, the PCB (8) varies the speed of the Fan Motor (26) to maintain the correct air
gas mix ratio.
7. When the hot tap (1) is closed, the pulse signal from theWater Flow Sensor (4) stops and
the burner flame is extinguished by closing the gas valve. The post purge operation then
commences to cool the heat exchanger (20).
8. Once the post-purge operation is completed power to the Fan Motor (26) is cut and the
Fan (25) stops.
9. When the water temperature within the auxiliary hot water storage tank drops below the
set point the surface mounted thermostat will provide power to the 500W booster
element (31)to boost the storage water temperature to 70ºC.

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
REV A Issued 08/13
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Sequence of Operation Component Diagram
BYPASS OPERATION
The bypass is a section of copper pipe work connected between the water body assembly
and the outlet of the heat exchanger and allows a quantity of cold water to bypass the heat
exchanger. The purpose of the bypass is to ensure the heat exchanger operates at
temperatures above the dew point of the combustion gases, ensuring condensate is not
produced, but low enough to maximise the heat exchanger life. The PCB activates the water
bypass control motor based on the heat exchanger temperature and the selected outlet
water temperature.
ANTI-FROST HEATER CIRCUIT
All models have an anti frost heater circuit. The anti-frost heaters are wired in series and
operate independently from the water heater.
A thermostat sensing ambient air temperature, positioned in the wiring loom near the bottom
of the water heater, activates the anti-frost heaters when the ambient air temperature falls to
4ºC +4ºC/-2ºC and deactivates the anti-frost heaters when the temperature rises above
12ºC.
In the event a heater block becomes open circuit the total heater circuit is rendered
inoperable. There are six anti-frost heaters in total.
Refer to „Anti-Frost Heaters‟ on page 55 for replacement procedure.

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
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COMPONENTS AND THEIR FUNCTION
PCB (Printed Circuit Board) -The control board that processes all the inputs required to
make the heater operate.
Water Body Assembly -A two part component that comprises the water flow control
assembly and the water bypass control assembly:
Water flow control assembly –A motor-actuated valve operates to restrict the flow
rate through the appliance, if necessary, to ensure that the required outlet
temperature is achieved. The water flow sensor and cold water inlet thermistor are
also housed in this assembly.
Water bypass control assembly –A motor-actuated valve is opened to allow a
proportion of inlet water to bypass the heat exchanger under certain operating
conditions.
Water Flow Sensor -An axial turbine positioned in the inlet water stream and provides a
pulse signal to the appliance electronic system, indicating the rate of water flow.
Proportional Gas Flow Regulator Valve (P.G.R.F.) -Provides electronic control of gas
pressure supplied to burner injectors.
Flame Rod - Safety device that detects the presence of flame.
Igniter - Spark igniter that lights the main burner. Ignition is by means of a high-voltage
spark applied to an electrode at one end of the burner assembly.
Thermistor(s) -Electronic thermostat that is used to measure temperature. There are four
thermistors located in the water heater: cold water inlet, hot water outlet, heat exchanger
and ambient air.
Cold Water Inlet Connection -Copper alloy casting, located right of centre in the bottom
panel of case. Incorporates the in-line strainer.
Strainer - In-line filter on the cold water inlet assembly that filters out debris and sediment.
Hot Water Outlet Connection -Copper alloy casting, located at the left hand side in the
bottom panel of case. Delivers hot water to the piping system and measures the hot water
outlet temperature with the aid of a thermistor.
Gas Inlet Connection –Aluminium tube with ¾” BSP male thread to connect the incoming
gas supply. Incorporates the inlet gas pressure test point.
Fan Assembly -Combustion air is supplied by a variable speed fan. A pulse generator on
the fan motor shaft provides a signal to the appliance electronic system, confirming the
rotation of the fan.
Burner Assembly -Burner component that ignites the fuel-air mixture and provides heat for
the heat exchanger.

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
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Burner Manifold: The manifold consists of an aluminium die-casting sealed with a
press-formed steel plate and cork gasket. Cast galleries convey gas from the staging
solenoid valves to the injector orifices, which are machined into the side of the manifold that
faces the burner venturis.
Gas type connector -Removable electronic chip that programs the fuel type, product type
and model number.
Overheat Limiter - A plastic film that is wrapped around the combustion chamber and is
printed with a conductive path that is connected to the control system. In the event of
excessive temperature external to the heat exchanger, the conductive path will be broken
and the water heater will shut down.
Heat Exchanger –Consists of a number of finned copper tubes that cross the top of the
combustion chamber and absorb heat from the flue gases and transfer it to the water that is
passing through the tubes. There are nine copper tubes each with an outside diameter of
16mm and a wall thickness of 0.7mm. Each tube has 0.3mm thick copper fins.
Primary Flue - An exhaust hood, made from 0.6 mm thick stainless sheet steel, carries the
flue gases from the outlet of the combustion chamber to the flue way terminal.
Flue Way Terminal - An exhaust hood made from 0.5 mm thick stainless steel sheet that
projects through a slot in the upper part of the appliance front cover and directs the flue
gases horizontally away from the appliance.
Anti-Frost System - Electrical resistive heaters are activated by an ambient air sensing
thermostat to heat critical parts of the water system in the event of freezing conditions.
Heating Unit (Element) - A tubular device containing an electric resistance element that
converts electrical energy to heat. Standard rating is 500W.
Thermostat - A device, sensitive to temperature, which controls the supply of electrical
energy to the heating unit to maintain the heated water at the required temperature of 70ºC.
The thermostat incorporates an energy cut-off (ECO), which provides double pole
disconnection and requires manual operation to reset. The thermostat temperature setting is
not adjustable.
Temperature and Pressure Relief Valve (T&PR) - A valve designed to provide automatic
relief by discharging water in case of excessive temperature, pressure or both.
Auxiliary Hot Water Storage Tank - A 2.6L storage vessel that houses the heating unit,
thermostat and T&PR valve. The container is constructed of copper with no internal coatings
and is insulated with „fire retardant‟ expanded polystyrene foam (EPS).
Transfer Valve - A temperature actuated bypass valve that will bypass when inlet water
temperature is above the set temperature. The factory set temperature range is in the
vicinity of 42-46ºC. The transfer valve is not user adjustable.

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
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IN-SERIES GAS BOOSTING
This water heater is NOT suitable for installation or operation as an in-series gas
booster to a solar water heater, and should not be used for this purpose.
REMOTE TEMPERATURE CONTROLLERS
Standard or Deluxe remote temperature controllers are not suitable to be used in
conjunction with this product.
EZ-LINK™SYSTEM
The EZ Link system cannot be used in conjunction with this product.
TEMPERING VALVES
This water heater can deliver water at temperatures which can cause scalding.
It is necessary and we recommend that a temperature limiting device be fitted between an
874W27 series water heater and the hot water outlets in any ablution and public areas such
as a bathroom, ensuite or public amenities, to reduce the risk of scalding. The installing
plumber may have a legal obligation to ensure the installation of this water heater meets the
delivery water temperature requirements of AS/NZS 3500.4 so that scalding water
temperatures are not delivered to a bathroom, ensuite or other ablution or public area.
Where a tempering valve is fitted and there is not a separate untempered line for the kitchen
or laundry areas the maximum achievable hot water temperature will be 50ºC. To enable
delivery of hot water at temperatures above 50°C a separate untempered line must be
provided that supplies hot water exclusively to kitchen and laundry areas (refer to diagram).
LEGEND

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
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MAINTENANCE INFORMATION
Information relating to both the current and past operation of the water heater can be
obtained from the memory; this information is referred to as the maintenance information.
The table below details the information that can be recalled from the memory.
Left digit in LED display (Numerical) - Use DOWN (▼)arrow key on Remote Control
0
1
2
3
4
5
6
7
8
9
Right digit (Alphabetical) –Use UP (►) arrow key on Remote Control
E
Management
Number
Error Code for the previous 8 faults
Null
F
Null
Sequence number of the previous 8 faults
Null
C
Total combustion
starts X 10,000
Total combustion operations since last error X 10,000
Null
D
Total combustion
starts X 100
Total combustion operations since last error X 100
Null
H
Total combustion
period X 1000 hrs
Total combustion period since last error X 1,000 hours
Null
J
Total combustion
period X 10 hrs
Total combustion period since last error X 10 hours
Null
Y
Flame sensor status (See table below)
Water Flow Sensor Litres / minute
Ambient Air Thermistor temp. ºC
Water Inlet Thermistor temp. ºC
Heat Exchanger Thermistor temp ºC
Hot Water Outlet Thermistor temp ºC
Fan speed X100 RPM
Power for P.G.F.R Valve
Null
Null
A
Null
Control Line Voltage
Fan Detective Value
Fan Motor Current
Fan Motor Current Curve (Average)
Fan Motor Current Curve (After closing tap)
Fan Motor Current Curve (Combustion)
Null
Null
Sequence number
Eg: to view the current temperature being measured by the outlet thermistor select 5Y. Refer
to page 14 for the procedure to display maintenance information.
Flame Sensor Status
The chart below explains the maintenance information displayed at cell 0y:
0y display
00
01
X = Not detecting flame
O = Is detecting flame
Flame Rod 1
X
O

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
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Displaying Maintenance Information
Without Remote Controller:
Voltages up to 240 volts will be present within the water heater, take care
not to touch wiring terminals. Use an insulated tool when operating the DIP
switch or MIN and MAX buttons.
1. Remove the front cover from water heater.
2. Switch dip switch 1 to the ON (up) position on the DIP1 set of dip switches.
3. The LED1 display at bottom right hand side of water heater will display 1E.
4. Use the MIN button to change the left digit (0→1etc.) in the display to the
required maintenance code identified from the maintenance information
table on page 13.
5. Use the MAX button to change the right digit (E→F etc.) in the display to the required
maintenance code identified from the maintenance information table on page 13.
6. The maintenance code and the value of that code will alternate on the LED display.
7. If required, the maintenance information can be locked and will be unable to be modified
by turning dip switch 2 to the ON (up) position on the DIP1 set of dip switches whilst dip
switch 1 is also in the ON (up) position.
8. Switch all DIP1 dip switches to the OFF (down) position to return to normal operation.
With Remote Controller (a remote may only be used to assist during servicing):
Isolate power whilst connecting a remote controller.
1. Fit remote controller.
2. Restore power supply and ensure the remote controller is turned off.
3. Press the temperature increase and decrease buttons simultaneously for 3 seconds until
an audible beep is heard.
4. Use the temperature decrease button to change the left digit (0→1etc.) in the remote
controller display to the required maintenance code identified from the maintenance table
on page 13.
5. Use the temperature increase button to change the right digit (E→F etc.) in the remote
controller display to the required maintenance code identifiedfrom the maintenance table
on page 13.
6. The maintenance code and the value of that code will alternate on the LED display of the
Remote Controller.
7. Press the on/off buttontwice on the remote controller to cancel maintenance information.
To turn the unit on while in Maintenance Mode, quickly press the ON/OFF button once. The
temperature will default to 50oC but will not display so maintenance information can be
displayed. If a hot tap is opened, the unit will operate and the “Y” maintenance information
can be viewed in real time (flow rate in litres per minute, flame rod status etc).
Clearing the Fault History
1) Turn the unit OFF. Remove the front cover. Locate the dip switches on the control board.
2) Make sure all the dip switches are in the OFF (down) position.
3) On the DIP1 set of switches, switch dip switch 1 ON (up) and OFF (down) again.
4) Within 5 seconds of turning the dip switch off, press and hold the MIN (SW1) or MAX
(SW2) button. The LED display will flash „CL‟. Once flashing ceases the fault history has
been cleared and the MIN or MAX button can be released.
5) Verify clearing of fault history by entering Maintenance Mode and check the code at
location 1E; it should read -- (no record).

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TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
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About the Operational Flow Charts
The Operational Flow Charts provide information on the start up sequence and, in the event
a failure occurs at any point of the start up sequence, what error code will be displayed. Error
codes are displayed via the red LED mounted on the PCB.
The Sequence Number Table below indicates the section of the operational sequence
(boxed numbers on the operational flow chart) where the fault occurred.
Circled numbers, adjacent to the component or function, indicate the diagnostic test point
required to diagnose the fault. Refer to the table on page 21.
By locating the error code in the diagnosis charts the component/s or fault can be quickly
identified and tested using the diagnostic procedures outlined in this manual.
Notes and Abbreviations used in the Operational Flow Charts
P.G.F.R Valve
Proportional Gas Flow Regulating Valve
F.F
Flame Failure
G.I.S.V.
Gas Inlet Solenoid Valve (SV0)
S.V. 1
Solenoid Valve 1
O.H.L
Over Heat Limiter
S.V. 2
Solenoid Valve 2
I.U.I
In Use Indicator (Combustion Indicator)
S.V. 3
Solenoid Valve 3
Stepping gas rate change sequence by solenoid
Model
Step 1
Step 2
Step 3
027
SV1 ON
SV1 & 2 ON
SV 1, 2 & 3 ON
Sequence Number Table
Sequence Number
- 0 to -9
A0 - A9
P0 - P9
C0 - C9
E0 - E9
H0 - H9
J0 - J9
L0 - L9
Operational Flow Chart Section
1
2
3
4
5
Test Equipment
A list of test equipment which will assist in conducting diagnostic procedures is provided
below. This equipment is available from Rheem Service Spare Parts Department.
Flame detection simulator
WH0020080
Flame sensor current (uA) detection kit
WH0020081
Fine probe adapter kit
WH0020082
Heat exchanger fin brush
WH0020083
Probe to alligator clip kit
WH0020084

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OPERATIONAL FLOW CHARTS
Plug In
Power On
Operational Flow Chart 1
1
Functional
problem on gas
type circuit board
Communication
problem between
remote controller
and the heater
Fan motor current
detection failure G.I.S.V control failure
82 Flashing 76 Flashing
79 Flashing 71 Flashing
Error code cleared Isolate Power
Remote controller
switched on
Remote controller
switched off
Remote controller
display off
Remote controller
display on
On/Off lamp Off
On/Off lamp On
Fan On
Fan Off
10 seconds later
5
14 Flashing
Over heat limiter
failure
YES
B
Bath fill
operation
Water Flow Sensor
off
Hot water tap closed
Hot water tap open
2
3
YES
24 Flashing
NO
20 seconds later Fan On
Fan On
YES
4
FF1
5 31 Flashing
YES
32 FlashingNO6
33 FlashingNO
YES
7
YES
17 34 FlashingNO
YES
4 61 FlashingNO
5 seconds later
YES
8 72 FlashingYES
5 seconds later
Leakage >
than 0.1uA
P.G.F.R Valve on
NO
9
1
2
NO
YES
YES NO
NO
A
Initial check
normal? NO
Water flow
sensor on?
Max & Min
buttons off?
Inlet
thermistor ok? NO
Heat exchanger
thermistor ok?
Outlet
thermistor ok?
Ambient air
thermistor ok?
Fan speed
normal?
False flame
detected?
G.I.S.V (SVO) on10
Igniter on
P.G.F.R Valve off
11
S.V.3 (SV3) on18
EInput temp
> 60ºC or >
set temp?
Input temp < or =
58ºC & < or = set
temp - 2ºC?

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FF1
11 Flashing
Operational Flow Chart 2
S.V. 2 (SV2) on13
P.G.F.R Valve on9
S.V. 1 (SV1) off
Igniter off
P.G.F.R Valve off
S.V. 3 (SV3) off
S.V. 2 (SV2) off
I.U.I. Off
Leakage >
than 0.1uA
NO
3 seconds later
NO
P.G.F.R Valve off
YES
G.I.S.V (SVO) off
S.V. 1 (SV1) off
S.V. 2 (SV2) off
S.V. 3 (SV3) off
I.U.I on
Igniter off
YES
Proportional temperature
adjustment
Gas rate change-over
done by solenoid valves
Hot water volume adjustment
14
Solenoid bypass valve on Solenoid bypass valve off
YES
NO
10 Flashing
YES
3
31 Flashing 32 Flashing 33 Flashing 34 Flashing 35 Flashing 79 Flashing 14 Flashing 29 Flashing
99 Flashing16 Flashing 71 Flashing 76 Flashing 61 Flashing 81 Flashing 65 Flashing 52 Flashing
NO
NO
YES
Outlet water
temp exceeded
97ºC for more
than 15 seconds
15 Flashing
Water inlet
thermistor
disconnected
Outlet water
temperature
too high
Heat
Exchange
outlet temp too
low
Abnormal
combustion
Heat
exchanger
thermistor
disconnected O.H.L failure
Fan motor
current
detection
failure
Thermistor
connections
crossed
Ambient air
thermistor
disconnected
Outlet
thermistor
disconnected
G.I.S.V control
failure
Communication
problem between
remote controller
and water heater
Abnormal fan
speed Post purge failure
Malfunction of
water volume
control motor
P.G.F.R
control failure
A
Flame Detected?
Set temp.
46ºC or lower?
Low rate
combustion?
Heat exchange
outlet temp too
low?
05 Flashing
YES
NO
Ignition
Failure Flame Failure
I.U.I. Off
First Ignition
Trial?
11 Flashing
12 Flashing
NO
S.V. 1 (SV1) off
P.G.F.R Valve off
S.V. 3 (SV3) off
S.V. 2 (SV2) off
YES
E
Safety device
working?
First ignition
trial?
S.V. 1 (SV1) on12
Igniter off
G.I.S.V (SVO) off
66 Flashing
Malfunction of
water bypass
control motor

This document is stored and maintained electronically by Service. All printed copies not bearing this statement in RED are deemed “uncontrolled”
Hot water tap closed
Operational Flow Chart 3
G.I.S.V (SVO) off
or
[S.V. 1-3 (SV1-3) off]
YES
YES
NO
YES
Approx. 6 minutes later
P.G.F.R Valve at
minimum
4
5
Post Purge Shut Down Function
Water flow sensor off
Fan motor at minimum
I.U.I off
S.V. 1-3 (SV1-3)
failure
80 Flashing
8 seconds later NO
G.I.S.V (SV0) failure
51 Flashing
G.I.S.V (SVO) off
[S.V. 1-3 (SV1-3) off]
P.G.F.R Valve off
Fan off
YES
Abnormal combustion
NO
99 Flashing
Fan off
Isolate power
Locate and repair fault.
Clear error code 99.
S.V. 1 (SV1) off
S.V. 2 (SV2) off
Fan off
S.V. 3 (SV3) off
G.I.S.V (SV0) off
Isolate power
Locate and repair fault
and restore power
10 seconds later
10 seconds later
Flame current
detected less than
0.1uA?
Fan motor speed
checked during
operation?
Fan motor current
check ok?
P.G.F.R valve off

19
TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
REV A Issued 08/13
This document is stored and maintained electronically by Service. All printed copies not bearing this statement in RED are deemed “uncontrolled”
ERROR CODES
Code
Fault
Point to Check
05
Imperfect Combustion
Alarm
Clean air inlet filter. Clean combustion air fan. Clean heat exchanger
fins. Check for adequate combustion air ventilation openings and
clean if necessary.
10
Air Supply or Exhaust
Blockage
Warning code not a fault code.
Check all vent components for proper connections. Ensure there are
no restrictions in the flue inlet or exhaust. Ensure heat exchanger fins,
fan, and air intake are not blocked.
11
No Ignition
Ensure gas supply to the appliance is turned ON. Ensure gas type
and pressure is correct. Bleed all air from gas lines. Ensure gas line,
meter, and regulator are sized properly. Ensure appliance is properly
grounded. Check gas solenoid valves for open or short circuits.
Ensure igniter is operational. Check igniter wiring harness for
damage.
12
Flame Failure
Ensure gas type and pressure is correct. Bleed all air from gas lines.
Ensure flame rod wire is connected. Check flame rod for carbon
build-up. Ensure gas line, meter, and regulator are sized properly.
Ensure appliance is properly grounded. Check gas solenoid valves
for open or short circuits. Check power supply for proper voltage and
voltage drops. Disconnect and re-connect all wiring harnesses on unit
and PCB.
14
Overheat Limiter Fault
Ensure high fire and low fire manifold pressure is correct. Check gas
type of unit and ensure it matches gas type being used. Check heat
exchanger for cracks and/or separations. Check gas type connector.
Check for restrictions in airflow around unit and vent terminal.
15
Boiling Safety Device
Check for closed water heater inlet valve or restrictions in cold water
inlet pipe (must be fully open). Check for clogged heat exchanger
(scale build up).
16
Over Temperature Warning
Check for clogged heat exchanger. Check for restrictions in airflow
around unit and vent terminal.
24
Malfunction of Operational
Switch
Verify unit is electrically grounded. Press max button on PCB to reset;
Press min button on PCB to reset.
29
Heat Exchanger Outlet
Temp. Too Low
Clean heat exchanger fins.
31
Water Inlet Temperature
Sensor Fault
Check sensor wiring is intact and not damaged. Check and clean
scale from sensor if necessary. Ensure resistance is correct.
32
Heat Exchanger
Temperature Sensor Fault
33
Outgoing Water
Temperature Sensor Fault
34
Ambient Air Temperature
Sensor Fault
35
Improper Thermistor
Connection
Check that all thermistors are connected to proper connections on
PCB. Ensure the hot and cold plumbing to the heater is not reversed.

20
TM061 Rheem 27 Water Star Service Instructions –Issued: 11/10
REV A Issued 08/13
This document is stored and maintained electronically by Service. All printed copies not bearing this statement in RED are deemed “uncontrolled”
Error Codes (continued)
Code
Fault
Remedy
51
Gas Inlet Solenoid Valve
Fault
Check gas inlet solenoid valve wiring harness for loose or damaged
terminals.
52
PGFR Valve Fault
Check PGFR valve wiring harness for loose or damaged terminals.
61
Combustion Fan Failure
Ensure fan motor will turn freely. Motor will operate with a small
amount of restriction. Check wiring harness to motor for damaged
and/or loose connections.
65
Water Volume Control Fault
Check water flow solenoid valve wiring harness for loose or damaged
terminals. Check for proper voltage to water flow solenoid.
66
Water By-Pass Control Fault
Check water by-pass solenoid valve wiring harness for loose or
damaged terminals. Check for proper voltage to water by-pass
solenoid.
71
Gas Inlet Solenoid Valve
Control Fault
Check gas inlet solenoid valve wiring harness for loose or damaged
terminals. Ohm out solenoid valve.
72
Flame Sensing Device Fault
Ensure flame rod is touching flame when unit fires. Check inside
burner chamber for any foreign material blocking flame at flame rod.
Check all wiring to flame rod for damage. Check flame rod for proper
voltage. Remove flame rod and check, clean with steel wool.
76
Communication Fault with
Remote Control
Only applicable if a remote control has been connected to
provide diagnostics during fault-finding as remotes are not to
be used as standard with this product. Check remote control
wiring for loose or damaged connections. Bypass remote control
cable by connecting remote control directly to remote control
terminals on PCB. Replace cable if found to be faulty.
79
Fan Motor Current Fault
Ensure fan motor will turn freely. Motor will operate with a small
amount of restriction. Check fan motor for proper voltage and for
water (condensation) damage.
80
Gas Cut-off Failure
Ohm out all solenoid valves. Check voltage of all flame rods.
82
PCB data failure. Control
board is not programmed.
Ensure gas type connector is fitted.
99
Fan Motor cannot vent
Clean Air Inlet Screen; Clear vent blockages Check for blocked heat
exchanger.
No
code
Heater does not operate
when water is flowing
through unit.
Make sure unit is connected to proper power supply and circuit
breakers are on. Clean inlet water supply filter. Ensure at least the
minimum flow rate required is present. On new installations ensure
hot and cold water lines are not crossed.
No
code
Hot water takes too long to
arrive once hot tap opened.
Check transfer valve, element and thermostat operation.