Rheem 871018 Operating instructions

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SERVICE INSTRUCTIONS
18 & 20L Integrity
Electronic Gas Instantaneous Water Heater
TM002
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875020

TM002 Integrity 18 & 20L Service Instructions REV: E
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Contents
Safety Warning ....................................................................................................................3
Introduction ..........................................................................................................................3
Water Heater Model Identification........................................................................................3
Specifications.......................................................................................................................4
Preset Temperature Adjustment ..........................................................................................5
Wiring Diagram - Models with Mechanical Bypass ..............................................................6
Wiring Diagram - Models with Solenoid Operated Bypass...................................................7
Sequence of Operation........................................................................................................8
Bypass Operation ................................................................................................................9
Anti-Frost Heater Circuit ....................................................................................................10
Product Changes ...............................................................................................................10
Software Changes..........................................................................................................10
In-series Gas Boosting.......................................................................................................11
Tempering Valves..............................................................................................................16
Remote Controllers............................................................................................................16
Standard Controller ........................................................................................................17
How to Fault Find...............................................................................................................19
Operational Flow Charts ....................................................................................................21
Error Codes .......................................................................................................................24
Diagnostic Test Points .......................................................................................................25
Maintenance Information ...................................................................................................26
Displaying Maintenance Information ..............................................................................27
Clearing Error Code History...............................................................................................27
Resetting Error Codes .......................................................................................................28
Fault Diagnosis Sequence (Fault Finding Chart G) ...........................................................29
Fault Finding Chart 1 .........................................................................................................30
Fault Finding Chart 2 .........................................................................................................32
Fault Finding Chart 3 .........................................................................................................34
Fault Finding Chart 3.1 ......................................................................................................36
Fault Finding Chart 3.2 ......................................................................................................37
Fault Finding Charts 3.3 and 3.5........................................................................................39
Fault Finding Chart 3.6 ......................................................................................................40
Fault Finding Chart 3.7 ......................................................................................................42
Fault Finding Chart 3.8 ......................................................................................................43
Fault Finding Charts 4 and 4.1...........................................................................................44
Fault Finding Chart 4.2 ......................................................................................................45
Fault Finding Chart 4.3 ......................................................................................................46
Burner Gas Pressure Check ..............................................................................................47
Component Replacement Procedures...............................................................................48
Exploded View 1 – 871018 & 871020 Models ...................................................................55
Exploded View 2 – 871018 & 871020 Models ...................................................................57
Exploded View 3 – 871/875018-B & 871/875020-B Models ..............................................59
Exploded View 4 – 871/875018-B & 871/875020-B Models ..............................................61
Gas Type Conversion Procedure.......................................................................................63
Warranty ............................................................................................................................64
Document Revision History................................................................................................65

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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
Rheem Instantaneous Gas Water Heater 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.
Certain diagnostic procedures outlined in these Service Instructions
require “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.
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.
Introduction
The information provided in these instructions is based on the water heater being installed
in accordance with the Installation Instructions provided with each water heater.
Should you require further technical advice on a Rheem Integrity Water Heater, contact
your nearest Rheem Service Department where genuine replacement parts are also
available.
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.
8 7 1 018 N F -B
Model Number
8 - Rheem
2 - *Everhot
Location
7 - External
Ignition Type
1 - Electronic 60ºC Max temp
5 - Electronic 48ºC Max temp
Capacity
Nominal litres/minute @ 25 ºC rise
Gas Type
N - Natural
P - Propane
F - Frost protection fitted
Version
Internal Use Only

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Specifications
Model
871018N0
871018NF
875018NF
871018NF-B
875018NF-B
871018PF
875018PF
871018PF-B
875018PF-B
871020N0
871020NF
875020NF
871020NF-B
875020NF-B
871020PF
875020PF
871020PF-B
875020PF-B
Specification Gas Type Natural Propane Natural Propane
Max hourly gas consumption (MJ/Hr) 157 157 157 157
Min hourly gas consumption (MJ/Hr) 24 24 24 24
Min inlet water pressure (kPa) 140 140 140 140
Max inlet water pressure (kPa) 1000 1000 1000 1000
Min inlet gas pressure (kPa) 1.13 2.75 1.13 2.75
Max inlet gas pressure (kPa) 3.5 3.5 3.5 3.5
Max burner gas test pressure (kPa) 0.903 1.50 0.903 1.50
Min burner gas test pressure (kPa) 0.182 0.32 0.182 0.32
Ignition System Continuous Spark
Standard 66 66 66 66Power (Watts)
Consumption Anti-frost* 124 124 124 124
Gas connection diameter (mm) R¾/20 R¾/20 R¾/20 R¾/20
Water connection diameter (mm) R½/15 R½/15 R½/15 R½/15
Relief Valve Pressure (kPa) 1750 1750 1750 1750
Kitchen Controller Y Y Y Y
Bathroom 1 Controller Y Y Y Y
Bathroom 2 Controller Y Y Y Y
Deluxe Kitchen Controller N N N N
Deluxe Bathroom 1 Controller N N N N
Deluxe Bathroom 2 Controller N N N N
* Maximum power consumption when anti-frost heaters are energised.

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Preset Temperature Adjustment
It is possible to choose a preset outlet water temperature setting when remote controllers
are not fitted. The water heater comes factory set at 50ºC on 871 series models or 48ºC
on 875 series models.
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 adjust the preset temperature:
1. Remove the front cover from the water heater.
2. Turn DIP SWITCHES 3 and 4 on (up position) on the I.C. Board. The current preset
temperature is displayed on the LED.
3. Press the MIN or MAX button, located under the DIP Switches, until the desired
temperature is displayed. Available temperatures are:
871 series models: 40ºC, 43ºC, 50ºC, 55ºC and 60ºC
875 series models: 40ºC, 43ºC and 48ºC
4. Turn DIP SWITCHES 3 and 4 off (down position). The temperature display is now
turned off.
5. Refit the front cover to the water heater.

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Wiring Diagram - Models with Mechanical Bypass

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Wiring Diagram - Models with Solenoid Operated Bypass

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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 (or preheated water if a solar preheater
is installed) enters the water heater and passes through the Water Flow Sensor (3) and
Heat Exchanger (19). Note: For 871020 model heaters fitted with a comparator the inlet
water temperature must be less than or equal to 57ºC and for 871020-B models the
inlet water temperature must be less than or equal to 58ºC and less than or equal to the
set point temperature minus 2ºC for operation to occur past this point; otherwise water
will pass straight through the heat exchanger and fan and burner operation will not
occur (for more information on this subject refer to the section titled ‘In-series Gas
Boosting’ on page 11).
2. The Water Flow Sensor (3) sends a pulse signal to the PCB (27). Once the pulse
signal reaches a pre designated frequency (at minimum flow rate) the PCB (27)
activates the Fan Motor (25) and the Fan (24) starts rotating.
3. After the Fan (24) completes a pre purge, the Gas Inlet Solenoid Valve (9),Gas
Solenoid Valve 1 (10) and Gas Solenoid Valve 2 (11) open at the same time. The
Proportional Gas Flow Regulating Valve (13) adjusts the gas flow rate to ensure
adequate gas for ignition and gas is then supplied to the Burner (15).
4. At the same time the Gas Solenoid Valves open the Igniter (16) starts sparking
continuously and ignites the gas at the Burner (15). After the flame sensor (18) detects
burner flame, the Proportional Gas Valve (13) begins to control the gas flow rate. If
there is a difference between the hot water temperature detected by the Hot Water
Outlet Thermistor (6) and that set on the water heater or selected on the remote
controller (if fitted) the PCB (27) adjusts the hot water temperature by opening and
closing the Gas Solenoid Valves 1 (10), 2 (11) and 3 (12) and adjusting the
Proportional Gas Flow Regulating Valve (13). The water flow rate is also adjusted via
the Water Flow Servo Motor (7) to ensure the selected temperature of hot water is
delivered.
5. As the gas flow rate, controlled by the Proportional Gas Flow Regulating Valve (13)
changes the PCB (27) varies the speed of the Fan Motor (25) to maintain the correct air
gas mix ratio.
6. When the hot tap (1) is closed, the pulse signal from the Water Flow Sensor (3) stops
and the burner flame is extinguished by closing Gas Solenoid Valves 1 (10), 2 (11), 3
(12) and the Gas Inlet Solenoid Valve (9). The post purge operation then commences.
7. Once the post-purge operation ends (up to 6 minutes) power to the Fan Motor (25) is
cut and the Fan (24) stops.

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Sequence of Operation Component Diagram 1 Hot Water Tap
2 Bypass Control Valve
3 Water Flow Sensor
4 Inlet Water Temperature Thermistor
5 Combustion Chamber Thermistor
6 Outlet Water Temperature Thermistor
7 Water Flow Servo Motor
8 Water Filter (Strainer)
9 Gas Inlet Solenoid Valve
10 Gas Solenoid Valve 1
11 Gas Solenoid Valve 2
12 Gas Solenoid Valve 3 (not fitted on 18 &
20L models)
13 PGFR Valve
14 Nozzle
15 Burner
16 Igniter
17 Igniter Electrode
18 Flame Sensor
19 Heat Exchanger
20 Over Temperature Limiter
21 Exhaust (Flue) Outlet
22 Combustion Chamber
23 Anti Frost Heater (Models with F in model
number only e.g. 871020NF)
24 Fan
25 Fan Motor
26 Drain Plug With Relief Valve.
27 PCB
Bypass Operation
The bypass is a section of copper pipe work connected between the water body assembly
(effectively the cold water inlet) 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 exchangers
life. A valve fitted to the water body assembly controls the bypass. Two types of bypass
valve are utilised in 18 and 20 litre Integrity’s.
Mechanical Bypass
Some models without a -B suffix in the model number utilise a mechanical bypass e.g.
871020NF and some models without a -B suffix utilise a solenoid operated bypass. To
determine what kind of bypass is utilised in models without a -B suffix compare the
appliance to the wiring diagrams on pages 6 & 7.
The mechanical bypass is a small spring loaded valve located in the water body assembly.
The spring is temperature sensitive, as the cold water temperature decreases the spring
tension increases reducing the amount of cold water flowing through the bypass. The
bypass operates at all times when water is flowing.
Solenoid Operated Bypass
Models with a -B suffix in the model number utilise a solenoid operated bypass e.g.
871020NF-B. Some models without a -B suffix also utilise a solenoid operated bypass e.g.
871020NF. To determine what kind of bypass is utilised for models without a -B suffix
compare the appliance to the wiring diagrams on pages 6 & 7.

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The solenoid operated bypass comprises a valve (located in the water body assembly)
that is controlled by a solenoid (mounted on the water body assembly). The PCB activates
the solenoid at the following predetermined temperatures:
Without Touch Pads: When the unit is preset at 40 or 43 degrees.
With Touch Pads: When temperatures from 37 to 46 degrees are selected.
At all other times the bypass does not operate.
Anti-Frost Heater Circuit
Models with an ‘F’ in the model number have an anti frost heater circuit e.g. 871020NF-B.
The anti-frost heaters are wired in series and operate independently from the water heater.
18 and 20 litre models have a 58-watt anti-frost system.
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. The total heater circuit measures 993.2 ohms.
The circuit is split into two sections with 4 heaters in total. To determine which section has
failed, isolate the power to the water heater and unplug the wiring connectors at the
thermostat, cord set and the water body assembly heater block. The heat exchanger and
hot water outlet heater’s resistance (3 heater blocks) is 719.2 ohms. The resistance of the
water body assembly heater is 274 ohms. Refer to Procedure 10 on page 51 for
replacement procedure.
Product Changes
Software Changes
Models manufactured after July 2006 have a change to the software which controls the
operation of the heater. When an inlet water temperature of more than 58ºC and more
than the set point temperature minus 2ºC is detected by the inlet water temperature
thermistor, the fan and burner will not operate.
This function has been introduced to enhance the operation of the water heater and
remove the need for a Solar Bypass Valve when the Integrity 20 is connected as an in-
series gas booster to a solar water heating system (for more information refer to ‘In-series
Gas Boosting’ on page 11). Note: 875 series models and 18 Litre Integrity’s are not
suitable for use as in-series gas boosters.
Models with the revised software have a -B suffix added to the model number i.e.
871020NF-B.

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In-series Gas Boosting
Temperature controllers must not be fitted if this water heater is installed
as part of a solar water heater system because water at a temperature
much higher than the controller setting can be delivered.
If a solar pre-heater has been installed to an existing Integrity water heater
installation then a solar bypass valve or a comparator must be fitted at this
water heater and any controllers, if fitted, must be disconnected and
removed. Note: models ending with -B do not require a solar bypass valve
or a comparator.
875 series models and 18 Litre Integrity’s are not suitable for use as in-
series gas boosters.
871020-B Models
Where an 871020-B model Integrity is installed to provide in-series gas boosting a solar
bypass valve or a comparator is not required. 871020-B models have had a change made
to the operating software which eliminates the need for either of these components.
The software now electronically mimics a bypass valve so that when the inlet water
temperature is above 58°C the fan and burner will not operate despite water flowing
through the heat exchanger. When the inlet water temperature is less than or equal to
58°C the burner will fire and boost the outlet temperature to 60°C provided the flow rate is
greater than 3 litres per minute. 20L models with modified software can be identified by a
B suffix in the model number i.e. 871020NF-B.
The preset outlet temperature of the Integrity, when installed as an in-series gas booster to
a solar water heater, must be set at 60°C for the system to operate correctly.
The factory preset outlet temperature of all Integrity models is 50°C; during a new
installation it will be necessary to reset the outlet temperature to 60°C. Refer to page 5 for
details on checking and adjusting the outlet temperature.
Note: If an 871020 model heater is replaced with an 871020-B model heater and the
existing 871020 heater is used as an in-line booster and has a solar bypass valve fitted,
the solar bypass valve must be removed and the plumbing connections remade directly to
the Integrity inlet and outlet water connections (refer to diagrams on pages 11 & 12).
In-series Gas Boosting 871020-B Solar Loline Installation
Note: This plumbing diagram
is also applicable to 871020
model heaters fitted with a
comparator.
For more information on
comparators refer to page
13.

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In-series Gas Boosting 871020-B Solar Hiline Installation
Note: This plumbing diagram is
also applicable to 871020 model
heaters fitted with a comparator.
For more information on
comparators refer to page 13.
871020 Models
Where an 871020 model Integrity is installed to provide in-series gas boosting a solar
bypass valve is fitted across the Integrity inlet and outlet water connections to prevent the
water heater from operating when the outlet water temperature from the solar system is
above 57°C (refer to diagrams on page 13). A disconnection union must always be
provided at the solar preheated water inlet and hot water outlet on the solar bypass valve
to allow for removal of the valve.
The solar bypass valve has been specifically designed to work with Rheem Integrity
871020 models heaters. Models ending with -B do not require a bypass valve. 875 series
model water heaters and 18 Litre Integrity’s are not suitable for use as in-series boosters.
The preset outlet temperature of the Integrity, when installed as an in-series gas booster to
a solar water heater, must be set at 60°C for the system to operate correctly.
The factory preset outlet temperature of all Integrity models is 50°C; during a new
installation it will be necessary to reset the outlet temperature to 60°C. Refer to page 5 for
details on checking and adjusting the outlet temperature.
There are two types of solar bypass valves currently in use (Paloma & RMC) and whilst
both operate in the same manner the plumbing arrangement at the valve differs according
to the type of solar bypass valve used (refer to diagrams on page 13). Solar bypass valves
are no longer available and if faulty are to be removed and a Comparator installed. Refer
to pages 13 & 14 for information on comparators.

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Note: If an 871020 model heater is replaced with an 871020-B model heater and the
existing 871020 heater is used as an in-line booster and has a solar bypass valve fitted,
the solar bypass valve must be removed and the plumbing connections remade directly to
the Integrity inlet and outlet water connections (refer to diagrams on pages 11 & 12).
Solar Bypass Valve Operation
When the water temperature entering the solar bypass valve is above 57°C a temperature
sensitive mechanism moves the valve spindle preventing water from entering the Integrity
and allowing the water to flow through the solar bypass valve to the hot water outlet.
If the water temperature from the solar storage tank entering the solar bypass valve is
below 57°C the temperature sensitive mechanism retracts the valve allowing water to
enter the Integrity and preventing flow through the solar bypass valve. The Integrity will
boost the water temperature to 60°C at the hot water outlet provided the flow rate is
greater than 3 litres per minute.
Replacement of Solar Bypass Valve with a Comparator
An electronic device called a Comparator (part number 052127) is
now available to replace the solar bypass valve and is suitable for
use on Rheem 871020 models heaters. NOTE: 20L models with a
-B suffix in the model number do not require either a solar bypass
valve or a comparator.
Solar bypass valves are no longer available and if faulty are to be
removed and a Comparator installed. Refer to page 14 for the
procedure on installing a comparator.
The purpose of the comparator is to interrupt the operation of the
burner when the inlet water temperature rises above 57°C.
The comparator is connected to the water flow sensor wiring and the inlet temperature
sensor (cold sensor) wiring; both these components are mounted on the water body within
the gas booster. The comparator monitors the inlet water temperature and when the
temperature rises above 57°C the comparator interrupts the signal from the flow sensor to
the PCB causing the burner to shut down.
Paloma Solar Bypass Valve RMC Solar Bypass Valve
Inlet water from
solar water heater
Hot water outlet

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Removing a Solar Bypass Valve and Installing a Comparator
1. Ensure power and water to the water heater is isolated.
2. Remove the front cover (refer to component procedure 1 on
page 48).
3. Locate the 2 pin wiring plug in the wiring loom to the cold
sensor mounted on the water body (refer to fig 1) and
disconnect.
4. Plug the 2 pin male and female connectors from the
comparator into the plugs attached to the cold sensor and the
main wiring loom (refer to fig 2). NOTE: If the comparator
connectors do not fit the cold sensor and main wiring loom
plugs the model is an 871020-B model which does not require
a comparator.
5. Locate the 3 pin wiring plug in the wiring loom to the flow
sensor (refer to fig 3) and disconnect
6. Plug the 3 pin male and female connectors from the
comparator into the plugs attached to the flow sensor and the
main wiring loom (refer to fig 4).
7. Position and secure the comparator in a safe position using
the existing wiring ties securing the wiring loom (refer to fig
5).
8. Refit the front cover.
9. Remove the bypass valve and associated fittings and connect the inlet and outlet pipe
work directly to the gas booster. NOTE: This may require the pipe work to be
extended; unions must be used at the inlet and outlet to enable removal of the gas
booster for serving if required (refer to diagrams on pages 11 & 12).
10. Restore water and power supplies.
Fig 1
Cold sensor
2 pin cold sensor wiring
plug disconnected
Fig 2
Comparator connected
to cold sensor wiring
Fig 3
3 pin flow sensor wiring
plug disconnected
Fig 4
Comparator connected to
flow sensor wiring
Fig 5
Comparator and wiring
secured in place

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In-series Gas Boosting 871020 Solar Loline Installation
Note: For 871020 model heaters fitted with a comparator refer to diagram on page 11. For
more information on comparators refer to page 13.
In-series Gas Boosting 871020 Solar Hiline Installation
Note: For 871020 model heaters fitted with a comparator refer to diagram on page 11. For
more information on comparators refer to page 13.

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Tempering Valves
875 series models comply with AS/NZS 3498 and therefore do not require a tempering
valve.
On 871 series models where a tempering valve is fitted and there is not a separate
untempered line for the kitchen or laundry areas, the Kitchen temperature controller will be
able to display temperatures above 50oC however the delivered water temperature at the
tap will be that set by the tempering valve which will be no hotter than 50oC.
To enable delivery of hot water at temperatures above 50oC a separate untempered line
must be provided that supplies hot water exclusively to kitchen and laundry areas (refer to
diagram below).
Remote Controllers
Integrity 18 and 20 Litre electronic instantaneous gas water heaters can be fitted with
optional remote controllers.
There are 2 types of controller available, standard or deluxe; however only standard
controllers can be used with an 18 or 20 litre Integrity.
Controller Type Bathroom 1 Bathroom 2 Kitchen
Standard 299854 299855 299853
Standard and deluxe controllers cannot be mixed in a single installation; an individual
water heater must have ALL standard type controllers fitted, other manufacturers’
controllers cannot be used.
One, two or three controllers can be installed, however if a Bathroom controller is installed
without a Kitchen controller then the maximum selectable hot water temperature will be
limited to 50oC when connected to an 871 series model or 48oC when connected to an 875
series model.

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875 series models are factory set and limited so that they cannot deliver water hotter than
48oC.
When no hot water is flowing, temperatures can be selected between 37oC and 43oC by
pressing and holding the temperature control buttons, to select temperatures above 43oC
press the temperature control button once for each selection.
A controller must be turned on and must display the ‘Priority’ indicator in order to allow
adjustment of water temperature.
When hot water is flowing, the temperature can be increased from 37oC to 43oC only.
The water temperature can be decreased from any setting whether hot water is flowing or
not.
Standard Controller
Note: If one or more controllers are installed, at least one must be on for the water heater
to operate. If all controllers are off the water heater will only deliver cold water.
Selectable Temperatures:
Kitchen Controller:
37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 50*, 55*, 60oC*
Bathroom Controllers:
37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 50oC*
* Temperatures above 48 degrees are not available on controllers fitted to 875 series
models as these units have a maximum selectable temperature of 48oC at all locations.
Controller
ON / OFF
button
Water
temperature
adjustment
buttons
Controller
display panel
(water temp or
water volume)
Controller
‘priority’ light
Controller
‘In use’ light
Water volume
button

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ON / OFF button
This button must be pressed once to turn on the controller. The
light in the button will glow when the controller is on. A
controller cannot be turned on if water is flowing from a hot tap.
To turn off a controller, press the on / off button once. The light
will go out. A controller can be turned off whilst water is flowing.
Priority light
This light will glow on a controller when that controller has
priority. The Bathroom controller(s), if they are turned on, have
priority over the Kitchen controller. Priority means that controller
has control of the water heater temperature setting. The water
temperature setting can only be adjusted by the controller that
has priority.
In use light
This light will glow on all controllers, whether they are on or off,
when hot water is flowing, regardless of which controller has
priority.
Display panel
The current temperature setting is displayed on all controllers
(whether hot water is flowing or not), when any controller is on.
If all controllers are off, then the display remains blank. The
water volume can also be displayed on the Kitchen controller.
The x10lsymbol glows when the water volume is displayed.
i(up button) The up button increases the temperature setting.
j(down button) The down button decreases the temperature setting.
water volume button (Kitchen controller only) – This feature enables an alarm to sound when a set volume of water has flowed through the water
heater (refer to notes below).
Water volume notes:
•The water volume function is designed to warn, by a beeping sound, that a certain
volume of water has been delivered from the water heater. It does not stop either the
flow of or the heating of water.
•The Kitchen controller does not require priority nor to be on in order to set the water
volume function.
•The water volume function can be set whilst a hot tap is open.
•The water volume alarm will only sound from the kitchen controller.
•The factory preset water volume is 180 litres.
•To turn off the water volume function before the alarm sounds, press the water volume
button twice.
•The water volume is measured as the water flows through the water heater. Therefore if
more than one hot tap is open, the alarm will respond to the total water volume drawn
from all taps and the expected water volume from the first tap will be decreased.
•If the hot tap is closed before the set water volume flows through the water heater and
the water volume button is left on, then the alarm will sound when the remaining water
volume is consumed during a later operation. To prevent the alarm from sounding,
press the water volume button twice to turn it off.

TM002 Integrity 18 & 20L Service Instructions REV: E
D.O.I: 7/11/2007
This document is stored and maintained electronically by Service. All printed copies not bearing this statement in RED are deemed “uncontrolled”
19
How to Fault Find
When conducting fault finding techniques it is important to understand that the same error
code with a different sequence number can be displayed at different points during the
operational sequence of the water heater. It is important to determine where the fault
occurred in relationship to the operational sequence of the water heater before
commencing fault finding tests, as the tests may differ even though the same error code
can be displayed.
If a fault occurs the LED display will alternate between the error code for the fault and a
sequence number that indicates where in the operational sequence of the water heater the
fault occurred. The operational flow charts are broken into 5 sections designated by boxed
numbers. The table on page 20 converts the sequence number displayed on the LED to
the appropriate operational flow chart section.
The flow diagram below outlines the recommended procedure to successfully diagnose,
test and rectify faults on the Integrity range of water heaters.
1
Identify sequence number and error
code displayed on LED.
2
Convert the sequence number
to an operational flow chart
section number using the
sequence number table
3
Locate the operational
flow chart section
identified in step 2
4
Locate the error code within
the operational flow chart
section identified in step 2 and
take note of where the fault
occurred during the
operational sequence.
5
Using the fault diagnosis flow
chart locate the correct fault
finding flow chart to use.
6
Follow the fault finding
flow chart identified in
step 5 until the error
code displayed on the
LED is located.
7
Conduct the necessary tests
outlined to identify and rectify
the fault.
8
Additional information on components, performance and past
history can be gained from the maintenance information
stored in the PCB.

TM002 Integrity 18 & 20L Service Instructions REV: E
D.O.I: 7/11/2007
This document is stored and maintained electronically by Service. All printed copies not bearing this statement in RED are deemed “uncontrolled”
20
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.
When a fault occurs, an error code and sequence number will alternate in the LED display.
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 25.
By locating the Error Code (displayed on the water heater or remote controller) 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 on 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 I.C Integrated Circuit
O.H.L Over Heat Limiter S.V. 1 Solenoid Valve 1
C.I Combustion Indicator S.V. 2 Solenoid Valve 2
Stepping gas rate change sequence by solenoid
Model Step 1 Step 2 Step 3
18/20L S.V. 1 ON S.V. 2 ON S.V. 1 & 2 ON
Burner Configuration (Burner Change-Over Assembly)
Model Burner 1 Burner 2
18/20L Right Solenoid (S.V. 1) Left Solenoid (S.V. 2)
Sequence Number Table
Sequence Number - 0 to -9 A0 - A9
P0 - P9 C0 - C9 E0 - E9 H0 - H9 J0 - J9
L0 - L9
U0 - U9
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