Rheem W27 Technical Document

This water heater must be installed and serviced by a qualified person.
Please leave this guide with the householder.
Owner’s Guide
and
Installation Instructions
Rheem 27 Water Star
Continuous Flow Gas Water Heater
874 series - W27 model

PATENTS
This water heater may be protected by one or more patents or registered designs in the name of
Rheem Australia Pty Ltd or Paloma Co., Ltd.
Rheem Australia Pty Ltd is the supplier of the Rheem range of continuous flow gas water heaters,
manufactured by Paloma Co., Ltd., a world leader in water heater technology and manufacture.
TRADEMARKS
®Registered trademark of Rheem Australia Pty Ltd.
™ Trademark of Rheem Australia Pty Ltd.
Note: Every care has been taken to ensure accuracy in preparation of this publication.
No liability can be accepted for any consequences, which may arise as a result of its application.
Warning: Upon completion of the installation and commissioning of the water heater, leave this guide
with the householder or a responsible officer. DO NOT leave this guide inside of the cover of the water
heater, as it may interfere with the safe operation of the water heater or ignite when the water heater is
turned on.

3
CONTENTS
HOUSEHOLDER - We recommend you read pages 4 to 16.
The other pages are intended for the Installer but may be of interest.
About Your Water Heater............................................................................................................ 4
Regular Care .............................................................................................................................. 10
Water Supplies........................................................................................................................... 12
Save A Service Call................................................................................................................... 14
Installation –Water Heater ....................................................................................................... 17
Connections –Plumbing .......................................................................................................... 23
Connections –Electrical........................................................................................................... 26
Wiring Diagram.......................................................................................................................... 27
Commissioning.......................................................................................................................... 28
Draining The Water Heater ....................................................................................................... 34
Warranty..................................................................................................................................... 35

4
ABOUT YOUR WATER HEATER
WATER HEATER APPLICATION
This water heater is designed for use in a single family domestic dwelling for the purpose of heating potable
water. Its use in an application other than this may shorten its life.
MODEL TYPE
The Rheem 27 Water Star®continuous flow gas water heater model you have chosen is for outdoor
installation only. This model has an extended manufacturer‟s warranty (refer to the Rheem warranty on
page 35).
The water heater has a maximum preset outlet temperature setting of:
874 series - 75°C
Water Star water saving function 70°C
A quantity of water is maintained within the Water Star cylinder at a fixed temperature, and water initially
discharged by this water heater at start-up may be at a temperature of up to 70°C before the water
heater normalises to its preset outlet temperature.
Note: This water heater is not suitable for installation or operation as an in-series gas booster to a solar
water heater, and must not be used for this purpose.
WATER HEATER OPERATION
A quantity of water is kept hot in an electrically heated, thermostat
controlled copper cylinder. When a hot tap is turned on, hot water is
supplied immediately from this cylinder.
Water flows through the heat exchanger of the water heater when a
hot tap is opened and the gas burners ignite to provide immediate
heating of the water. Heat produced by the burner is transferred to the
water through the heat exchanger. The water flow is initially diverted
into the copper cylinder until it reaches the preset outlet temperature
setting of the water heater. The water flow is then diverted away from
the cylinder directly to the outlet of the water heater.
The water flowing through the heat exchanger is heated to a constant
temperature by automatic adjustment of the gas supply to the burner to
suit the water flow rate. The gas burners extinguish when the hot tap is
closed. Water in the cylinder is kept hot until the next time a hot tap is
turned on.
Automatic safety controls are fitted to the water heater to provide safe
and efficient operation.
MAINS PRESSURE
The water heater is designed for direct connection to the mains water supply. If the mains supply pressure in
your area exceeds that shown on page 19, a pressure limiting valve must be fitted. The supply pressure
should be greater than 160 kPa for the rated flow and performance to be achieved.

ABOUT YOUR WATER HEATER
5
HOW HOT SHOULD THE WATER BE?
The water heater heats the water to the preset outlet
temperature setting. The factory preset outlet temperature
setting is:
874 series 60°C
Water Star water saving function 70°C
Water initially discharged by this water heater at start-up
may be at a temperature of up to 70°C before the water
heater normalises to its preset outlet temperature
Note: The preset outlet temperature setting of this water
heater cannot be adjusted by the householder. The setting
can only be adjusted by the installer, Rheem Service or their
nearest Accredited Service Agent.
Warning: Temperature controllers must not be fitted to this water heater (874 series) because water at a
temperature much higher than the controller setting can be delivered.
HOTTER WATER INCREASES THE RISK OF SCALD INJURY
This water heater can deliver water at temperatures which can cause scalding. Check the water temperature
before use, such as when entering a shower or filling a bath or basin, to ensure it is suitable for the
application and will not cause scald injury.
We recommend and it may be required by regulations that an approved temperature limiting device be fitted
into the hot water piping to the bathroom and ensuite when an 874 series water heater is installed. This will
keep the water temperature from exceeding 50°C at the bathroom and ensuite. The risk of scalding will be
reduced, and still allow hotter water to the kitchen and laundry.
THERMOSTAT
The thermostat automatically controls the electricity supply to the heating unit of the cylinder so a constant
temperature is maintained. The thermostat and its protective over temperature cut out is mounted inside the
front cover of the water heater. There is no need to switch the water heater off when it is not in use, except
when you are on an extended holiday. The thermostat is fully automatic and power is only used when
heating is required.
The thermostat on this water heater has a fixed setting at 70°C. This cannot be adjusted.
WARNING
This water heater is only intended to be operated by persons who have the experience or the knowledge and
the capabilities to do so. This water heater is not intended to be operated by persons with reduced physical,
sensory or mental capabilities i.e. the infirm, or by children. Children should be supervised to ensure they do
not interfere with the water heater.
The water heater uses 240 Volt AC electrical power for operation of the control systems and the combustion
fan. The removal of the front panel will expose 240 V wiring. It must only be removed by a qualified person.
The power lead from the water heater must be plugged into a weatherproof general purpose outlet (GPO).
Take care not to touch the power plug with wet hands.
Water Star thermostat setting
(not adjustable)
maximum recommended supply
temperature to bathrooms and
ensuites.
factory preset temperature setting
874W series

ABOUT YOUR WATER HEATER
6
SAFETY
This water heater is supplied with temperature sensors, a FlameSafe®protection system and a pressure
relief valve.
The Water Star water saving component within the water heater is supplied with a temperature limiting valve,
a thermostat, an over-temperature cut-out and a combination temperature pressure relief valve. The
operation of the over-temperature cut-out on the thermostat indicates a potentially dangerous situation. If the
over-temperature cut-out operates, it must not be reset and the water heater must be serviced by a qualified
person.
These devices must not be tampered with or removed. The water heater must not be operated unless each
of these devices is fitted and is in working order.
The general purpose outlet (GPO) this water heater is plugged into should be protected by an RCD (residual
current device). RCD‟s can provide additional protection should there be a fault in the electrical wiring
system. Check with your electrician if in doubt.
If the power supply cord or plug is damaged, it must be replaced by a qualified person in order to avoid a
hazard. The power supply cord and plug must be replaced with a genuine replacement part available from
Rheem. Phone Rheem Service or their nearest Accredited Service Agent to arrange for an inspection.
Warning: For continued safety of this water heater it must be installed, operated and maintained in
accordance with the Owner‟s Guide and Installation Instructions.
The Rheem warranty may not cover faults if relief valves or other safety devices are tampered with or
if the installation is not in accordance with these instructions.
Do not store flammable or combustible materials near the
water heater. Flammable liquids (such as petrol),
newspapers and similar articles must be kept well away from
the water heater and the flue terminal.
Do not use aerosols, stain removers and household
chemicals near the water heater whilst it is working. Gases
from some aerosol sprays, stain removers and household
chemicals become corrosive when drawn into a flame.
Do not store swimming pool chemicals, household
cleaners, etc., near the water heater.
Do not place anything on top of the water heater or in contact
with the flue terminal. Ensure the flue terminal is not
obstructed in any way at any time.
Do not use Propane / Butane gas mixtures in a Propane model. A Propane model is designed to operate
on Propane only. The use of Propane / Butane mixture, such as automotive LPG fuel, in a Propane
model is unsafe and can cause damage to the water heater.
PRECAUTIONS
Where damage to property can occur in the event of the water heater leaking, the water heater must be
installed over a safe tray. Construction, installation and draining of a safe tray must comply with
AS/NZS 3500.4 and all local codes and regulatory authority requirements.
The water heater must be maintained in accordance with the Owner‟s Guide and Installation Instructions.
Refer to “General Maintenance” on page 10, “Minor Six Month Maintenance” on page 10 and “Major Five
Year Service” on page 10.
If this water heater is to be used where an uninterrupted hot water supply is necessary for your application or
business you should ensure that you have back up redundancy within the hot water system design. This
should ensure the continuity of hot water supply in the event that this water heater were to become
inoperable for any reason. We recommend you seek advice from your plumber or specifier about your needs
and building back up redundancy into your hot water supply system.

ABOUT YOUR WATER HEATER
7
TO TURN OFF THE WATER HEATER
If it is necessary to turn off the water heater:
Switch off the electrical supply at the power outlet to the water heater if there is no risk of freezing
conditions occurring (refer to note below).
Close the gas isolation valve at the inlet to the water heater.
Close the cold water isolation valve at the inlet to the water heater.
Note: If there is a risk of freezing conditions, the electrical supply to the water heater should not be switched
off unless the water heater is drained, otherwise damage could result (refer to “Frost Protection”on page 7
and “Draining the Water Heater”on page 7).
TO TURN ON THE WATER HEATER
Screw in the drain plugs at the cold water inlet and hot water outlet of the water heater if the water
heater has been drained.
Open all of the hot taps in the house (don‟t forget the shower).
Open the cold water isolation valve fully at the inlet to the water heater.
Air will be forced out of the taps.
Close each tap as water flows freely from it.
Open the gas isolation valve fully at the inlet to the water heater.
Plug in the power supply cord at the power outlet.
Switch on the electrical supply at the power outlet to the water heater.
The water heater will operate automatically when you open a hot tap.
GOING ON HOLIDAYS
If you are going on holidays, it is not necessary to turn the water heater off. If it is necessary to turn off the
water heater, refer to “To Turn Off The Water Heater” on page 7.
FROST PROTECTION
The water heater has a frost protection system. The frost protection system will protect the water heater from
damage, by preventing ice forming in the waterways of the water heater, in the event of freezing conditions
occurring.
Notes:
The frost protection system will be rendered inoperable if electrical power is not available at the water
heater. Damage caused by freezing due to the unavailability of power at the water heater is not covered
by the Rheem warranty (refer to “Terms of the Rheem Warranty” on page 35).
If it is necessary to switch the power off to the water heater and there is a risk of freezing, then it is
necessary to drain the water heater (refer to “Draining the Water Heater” below).
Pipe work to and from the water heater must be adequately insulated to prevent freezing.
The water heater is not suitable for installation in areas where the ambient temperature falls below -20ºC
(including wind chill factor).
Refer to “Terms of the Rheem Warranty” on page 35.

ABOUT YOUR WATER HEATER
8
DRAINING THE WATER HEATER
Switch off the electrical supply at the power outlet to the water heater.
Close the gas isolation valve at the inlet to the water heater.
Leave the cold water isolation valve open at the inlet to the water heater.
Open a hot tap (preferably the shower outlet) for 20 seconds, to purge any hot water left in the water
heater.
Close the cold water isolation valve, and leave the hot tap remain open.
Unscrew the two drain plugs, one each at the cold water inlet and transfer pipe connection, on the
underside of the water heater.
A portion of water will drain from the water heater.
In order to drain the remainder of water inside the water heater, raise the lever of the temperature
pressure relief valve. The easing lever on the valve is accessed by removing this plastic cover panel.
Refer to “Accessing the Temperature Pressure Relief Valve” on page 11.
When water stops flowing from the drain plugs, gently lower the lever of the temperature pressure relief
valve, refit the plastic cover panel and close the hot tap.
Note: It is recommended not to screw the drain plugs back in, until the water heater is to be turned on again.
HOW DO I KNOW IF THE WATER HEATER IS INSTALLED CORRECTLY?
Installation requirements are shown on pages 17 to 22. The water heater must be installed:
by a qualified person, and
in accordance with the installation instructions, and
in compliance with Standards AS/NZS 3500.4, AS 5601 or AS/NZS 5601.1, as applicable under local
regulations, and all local codes and regulatory authority requirements.
Warning: Temperature controllers must not be fitted to this water heater (874 series) because water at a
temperature much higher than the controller setting can be delivered.
VICTORIAN CUSTOMERS
Notice to Victorian Customers from the Victorian Plumbing Industry Commission. This water heater must be
installed by a licensed person as required by the Victorian Building Act 1993.
Only a licensed person will give you a Compliance Certificate, showing that the work complies with all the
relevant Standards. Only a licensed person will have insurance protecting their workmanship for 6 years.
Make sure you use a licensed person to install this water heater and ask for your Compliance Certificate.

ABOUT YOUR WATER HEATER
9
DOES THE WATER CHEMISTRY AFFECT THE WATER HEATER?
The water heater is suitable for most public water supplies, however some water chemistries may have
detrimental effects on the water heater, its components and fittings. Refer to “Water Supplies” on page 12.
If you are in a known harsh water area or you are not sure of your water chemistry, have your water checked
against the conditions described on page 12.
HOW LONG WILL THE WATER HEATER LAST?
The water heater is supported by a manufacturer‟s warranty (refer to page 35). There are a number of
factors that will affect the length of service the water heater will provide. These include but are not limited to
the water chemistry, the water pressure, the water temperature (inlet and outlet) and the water usage
pattern. Refer to “Precautions” on page 6.

10
REGULAR CARE
GENERAL MAINTENANCE
The jacket of the water heater can be cleaned with a soft cloth and warm mild soapy water. Under no
circumstances should abrasive materials or powders be used.
The area around the water heater can be sprayed with insecticide to rid the area of insects. Insects
encroaching into or nesting in the water heater can interfere with the operation of the water heater and also
damage components.
MINOR SIX MONTH MAINTENANCE
It is recommended minor maintenance be performed every six months by the dwelling occupant.
The minor maintenance includes:
Inspect around the air inlet, flue terminal and the water heater in general for plant growth.
Trim back any shrubs, bushes or other plants which have encroached around the water heater.
Plant growth across the air let and flue terminal can interfere with the performance of the water
heater.
Inspect around the water heater for insect infestations, such as ants.
Spray insecticide around the water heater if necessary to rid the area of insects. Do not spray the
surface or into the air inlet or flue terminal of the water heater.
Insects encroaching into or nesting in the water heater can interfere with the operation of the water
heater and also damage components.
Operate the easing lever on the temperature pressure relief valve. It is very important you raise and
lower the lever gently. Refer to “Temperature Pressure Relief Valve” on page 11.
Warning: Exercise care to avoid any splashing of water, as water discharged from the drain line will
be hot. Stand clear of the drain line‟s point of discharge when operating the valve‟s lever.
Operate the easing lever on the expansion control valve (if fitted). It is very important you raise and
lower the lever gently. Refer to “Expansion Control Valve” on page 11.
Check the drain line from the safe tray (if one is installed) is not blocked.
MAJOR FIVE YEAR SERVICE
For safe and efficient operation, it is recommended a five year service be conducted on the water heater.
Warning: Servicing of a water heater must only be carried out by qualified personnel. Phone Rheem
Service or their nearest Accredited Service Agent.
Note: The five year service and routine replacement of any components, if required, are not included in the
Rheem warranty. A charge will be made for this work. Only genuine replacement parts should be used on
this water heater.
The five year service includes the following actions:
Check and if necessary adjust the gas pressure.
Check the operation of and clean the burner.
Replace the temperature limiting valve.
Replace the temperature pressure relief valve.
Inspect and flush the expansion control valve (if fitted). If required, replace the valve.
Check the electric heating unit for excessive calcium build up or corrosion and replace if necessary.
Visually check the unit for any potential problems.
Inspect all connections.
Check the drain line from the safe tray (if one is installed) is not blocked.

REGULAR CARE
11
TEMPERATURE PRESSURE RELIEF VALVE
This valve is near the top of the water heater and is essential for its safe operation. It is possible for the valve
to release a little water through the drain line during each heating period. This occurs as the water is heated
and expands by approximately 1/50 of its volume.
Continuous leakage of water from the valve and its drain line may indicate a problem with the water heater
(refer to “Temperature Pressure Relief Valve Running” on page 15).
Warning: Never block the outlet of this valve or its drain line for any reason.
Operate the easing lever on the temperature pressure relief
valve once every six months. It is very important you raise
and lower the lever gently.
The valve connects to the top of the cylinder and is located
underneath the plastic cover panel on the front of the water
heater. The easing lever on the valve can be accessed by
removing this plastic cover panel. Refer to “Accessing the
Temperature Pressure Relief Valve” on page 11.
DANGER: Failure to do this may result in the water heater
cylinder failing, or under certain circumstances, exploding.
Warning: Exercise care to avoid any splashing of water, as water discharged from the drain line will be
hot. Stand clear of the drain line‟s point of discharge when operating the valve‟s lever.
If water does not flow freely from the drain line when the lever is lifted, then the water heater must be
checked. Phone Rheem Service or their nearest Accredited Service Agent to arrange for an inspection.
The temperature pressure relief valve should be replaced at intervals not exceeding 5 years, or more
frequently in areas where there is a high incidence of water deposits (refer to “Water Supplies” on page 12).
Accessing the Temperature Pressure Relief Valve
The plastic cover panel is required to be
removed to access to temperature pressure
relief valve.
To access the valve:
1. Push the bottom end clip upwards and
gently pull out the plastic cover panel at the
bottom to disengage the clip.
2. Disengage the plastic cover panel from the water heater by
pushing the top end of the panel downwards.
3. Remove the plastic cover panel while holding both the
bottom and top ends of the panel.
4. Re-install the plastic cover panel securely by reversing the
steps above.
Note: The plastic cover panel forms part of the water heater. It must be resecured properly after servicing.
EXPANSION CONTROL VALVE
In many areas, including South Australia, Western Australia and scaling water areas, an expansion control
valve is fitted to the cold water line to the water heater. The expansion control valve may discharge a small
quantity of water from its drain line during the heating period instead of the temperature pressure relief valve
on the water heater.
Operate the easing lever on the expansion control valve once every six months. It is very important you
raise and lower the lever gently. The expansion control valve should be checked for performance or
replaced at intervals not exceeding 5 years, or more frequently in areas where there is a high incidence of
water deposits.
lift until water
flows from the
drain line –
lower gently
hot
water
cylinder
drain
line
Step 3
Step 1
Step 2

12
WATER SUPPLIES
This water heater must be installed in accordance with this advice to be covered by the Rheem
warranty.
This water heater is manufactured to suit the water conditions of most public reticulated water supplies.
However, there are some known water chemistries which can have detrimental effects on the water heater
and its operation and / or life expectancy. If you are unsure of your water chemistry, you may be able to
obtain information from your local water supply authority. This water heater should only be connected to a
water supply which complies with these guidelines for the Rheem warranty to apply.
Due to the nature of the water chemistry the copper cylinder is not covered by the water heater warranty
when this water heater is connected to the public water supply in the Redlands Shire in Queensland.
SATURATION INDEX
The saturation index (SI) is used as a measure of the water‟s corrosive or scaling properties.
In a corrosive water supply, the water can attack copper parts and cause them to fail. Where the saturation
index is less than –1.0, the water is very corrosive and the Rheem warranty does not apply to a copper heat
exchanger or a copper cylinder in a Water Star continuous flow water heater.
In a scaling water supply calcium carbonate is deposited out of the water onto any hot metallic surface.
Where the saturation index exceeds +0.40, the water is very scaling. An expansion control valve must be
fitted on the cold water line prior to the water heater to protect and for the Rheem warranty to apply to the
temperature pressure relief valve and copper cylinder.
Where the saturation index exceeds +0.80, the Rheem warranty does not apply to a copper heat exchanger,
a copper cylinder or a heating unit in a Water Star continuous flow water heater.
Water which is scaling may be treated with a water softening device to reduce the saturation index of the
water.
Refer to the Saturation Index chart below.
-1.0
no warranty applies to a:
temperature pressure relief valve or a
water heater cylinder unless an
expansion control valve is fitted.
no warranty applies to a:
-copper cylinder
SATURATION INDEX (SI)
WATER STAR WATER HEATER
WITHIN WARRANTY
SPECIFICATION
SATURATION INDEX
(calculated @ 80°C water temperature)
no warranty applies to a:
-standard watts density heating unit -copper cylinder
+0.4 +0.80
very corrosive very scaling
scaling
corrosive
no warranty applies to a: - Water Star continuous flow copper
heat exchanger or copper cylinder
-.heating unit
no warranty applies to a: - Water Star continuous flow copper
heat exchanger or copper cylinder
-.copper sheathed heating unit

WATER SUPPLIES
13
CHANGE OF WATER SUPPLY
The changing or alternating from one water supply to another can have a detrimental effect on the operation
and / or life expectation of a heat exchanger, a copper cylinder, a temperature pressure relief valve and a
heating unit.
Where there is a changeover from one water supply to another, e.g., a rainwater tank supply, bore water
supply, desalinated water supply, public reticulated water supply or water brought in from another supply,
then water chemistry information should be sought from the supplier or it should be tested to ensure the
water supply meets the requirements given in these guidelines for the Rheem warranty to apply.
SUMMARY OF WATER CHEMISTRY ADVICE AFFECTING WARRANTY
The water heater and its components are not suitable for certain water chemistries. Those chemistries are
listed below. If the water heater is connected at any time to a water supply with the following water chemistry,
the Rheem warranty will not cover any resultant faults on the components listed below:
Water Chemistry
Component
Saturation Index (SI) < -1.0
copper cylinder
copper heat exchanger
copper sheathed heating unit
Saturation Index (SI) > +0.4
(if expansion control valve is not fitted)
copper cylinder
temperature pressure relief valve
Saturation Index (SI) > +0.8
copper cylinder
copper heat exchanger
heating unit

14
SAVE A SERVICE CALL
Check the items below before making a service call. You will be charged for attending to any condition or
fault, which is not related to manufacture or failure of a part (refer to “Terms of the Rheem Warranty” on
page 35).
COLD WATER FROM THE HOT TAP
Close the hot tap, wait 10 seconds and open the hot tap again.
Is the hot tap open enough?
The burners will not light if the flow rate is less than 2.0 L / min.
Is the water heater plugged in and the power outlet switched on?
Is power available in the house?
Try using another electrical appliance.
Is the isolation valve in the gas line open?
Is there a gas supply to the rest of the house?
Try lighting another gas appliance.
Has the gas line been purged of air after installation?
Refer to your plumber.
NO WATER FROM THE HOT TAP
No flow of water from the hot tap may indicate a restriction in or failure of the cold water supply to the water
heater. Check for water flow at other taps and that the cold water isolation valve (refer to page 23)is fully
open.
WATER FLOW FLUCTUATES
More than two or three taps in use at the same time may cause a decrease in the hot water flow from the
taps.
Are there more than two or three taps open, or are appliances such as a dishwasher or washing
machine, in use at the same time?
Ensure only two or three taps or appliances are on at the one time.
Check the flow of the water from one tap, e.g., the shower.
The shower should be adjusted so the hot tap is fully open.
Water heater size
Do you have the correct size water heater for your requirements? The sizing guide in the sales literature
and on the Rheem website (www.rheem.com.au) suggests average sizes that may be needed.
FAN CONTINUES TO RUN AFTER WATER HEATER OPERATION STOPS
It is the normal operation of the water heater for the fan to continue running after heating of the water is
finished. The fan may run for up to six minutes after the burners extinguish, to prepare for the next ignition.

SAVE A SERVICE CALL
15
CLOUDS OF WHITE ‘VAPOUR’ FROM THE FLUE TERMINAL
During the heating cycle, it is not unusual to see water vapour clouds
steaming from the flue terminal, particularly on cold days. This is normal
operation of the water heater.
PRESSURE RELIEF VALVE DISCHARGING
A pressure relief valve is incorporated into the continuous flow side of the
water heater controls. This valve protects the water heater, by allowing
water to escape, in the event of excessive pressure build up in the
waterways.
Normal operation
A small volume of water may discharge from the bottom of the water
heater when a hot tap is suddenly closed.
Continuous dribble
A continuous dribble may indicate the water supply pressure is above
the design pressure for the water heater. If so, a pressure limiting
valve must be installed on the cold water supply pipe to the water
heater (refer to “Mains Water Supply”on page 19).
ERROR CODE
The water heater provides a diagnostic error code in the event of an interruption to its operation. The error
code is displayed on the OK MONITOR on the front of the water heater as a numerical value. If an error code
appears:
Close the hot tap and switch off the electrical supply to the water
heater.
Check the gas isolation valve at the gas inlet to the water heater is
fully open.
Wait 5 minutes, then switch on the electrical supply to the water heater
and open a hot tap.
If the error code persists, take note of the numerical code and turn off the hot tap. Phone Rheem Service or
their nearest Accredited Service Agent to arrange for inspection.
TEMPERATURE PRESSURE RELIEF VALVE RUNNING
Normal Operation
It is normal and desirable that this valve allows a small quantity of
water to escape during the heating cycle. However, if it discharges
more than a bucket full of water in 24 hours, there may be another
problem.
Continuous dribble
Try gently raising the easing lever on the relief valve for a few seconds
(refer to “Temperature Pressure Relief Valve” on page 11). This may
dislodge a small particle of foreign matter and clear the fault. Release
the lever gently.
Steady flows for long period (often at night)
This may indicate the mains water pressure sometimes rises above
the designed pressure of the water heater. Ask your installing plumber
to fit a pressure limiting valve.
Warning: Never replace the relief valve with one of a higher
pressure rating.
Heavy flows of hot water until water heater is cold - then stops
until water reheats
The water heater must be switched off at the isolating switch. Phone
your nearest Rheem Service Department or Accredited Service Agent
to arrange for an inspection.

SAVE A SERVICE CALL
16
EXPANSION CONTROL VALVE RUNNING
If an expansion control valve is fitted in the cold water line to the continuous flow water heater (refer to
page 24). it may discharge a small quantity of water instead of the temperature pressure relief valve on the
water heater. The benefit is that energy is conserved as the discharged water is cooler.
HIGHER THAN EXPECTED GAS OR ELECTRICITY BILLS
Should you at any time, feel your gas account is higher than expected, we suggest you check the following
points:
Is one outlet (especially the shower) using more hot water than
you think?
Carefully review the family‟s hot water usage. Inexpensive flow
control valves can be easily fitted to the shower outlets to reduce
water usage.
Has there been an increase in hot water usage?
An increase in hot water usage will result in an increase in water
heater operation.
Has your water heating tariff rate been increased by your gas
retailer since your previous account?
IF YOU HAVE CHECKED ALL THE FOREGOING AND STILL BELIEVE YOU NEED ASSISTANCE,
PHONE RHEEM SERVICE OR THEIR NEAREST ACCREDITED SERVICE AGENT.

17
INSTALLATION –WATER HEATER
THIS WATER HEATER IS FOR OUTDOOR INSTALLATION ONLY.
THIS WATER HEATER IS NOT SUITABLE FOR POOL HEATING.
Check the water heater is suitable for the gas type available (refer to the rating label on the water
heater)
INSTALLATION STANDARDS
The water heater must be installed:
by a qualified person, and
in accordance with the installation instructions, and
in compliance with Standards AS/NZS 3500.4, AS 5601 or AS/NZS 5601.1, as applicable under local
regulations, and all local codes and regulatory authority requirements.
All packaging materials must be removed from the water heater prior to its installation.
WATER HEATER APPLICATION
This water heater is designed for use in a single family domestic dwelling for the purpose of heating potable
water. Its use in an application other than this may shorten its life.
If this water heater is to be used where an uninterrupted hot water supply is necessary for the application or
business, then there should be redundancy within the hot water system design. This should ensure the
continuity of hot water supply in the event that this water heater was to become inoperable for any reason.
We recommend you provide advice to the system owner about their needs and building backup redundancy
into the hot water supply system.
Note: This water heater is not suitable for installation or operation as an in-series gas booster to a solar
water heater, and must not be used for this purpose.
WATER HEATER LOCATION
The water heater should be installed close to the most frequently used outlet and its position chosen with
safety and service in mind. Make sure people (particularly children) will not touch the flue terminal. The flue
terminal and air inlet must be clear of obstructions and shrubbery.
Clearance must be allowed for servicing of the water heater. The water heater must be accessible without
the use of a ladder or scaffold. Make sure the entire front panel can be removed for service. You must be
able to read the information on the rating plate. Remember you may have to take the entire water heater out
later for servicing.
This water heater must be installed vertically upright with the
water, gas and power connections on the underside, pointing
toward the ground. The back of the water heater can be
either against a wall or supported by a frame.
Note: The water heater must be well secured to the wall or
frame using two fasteners each at the top and bottom of the
unit (refer to page 21 for mounting hole positions and weight
of the water heater). Use the screws provided only if they are
suitable for the wall or frame type. Otherwise select and use
alternative fasteners suitable for the application. The
fasteners must be capable of bearing the full weight of the
water heater so it may not work loose nor impose any load on
the gas and water pipe work connected to the water heater.
Refer to the fastener manufacturer‟s information and
recommendations for the type of fastener to use for the wall
or frame type and load bearing requirements.
Refer to the typical installation diagram on page 22.

INSTALLATION –WATER HEATER
18
The water heater must not be installed in an area with a corrosive atmosphere where chemicals are stored or
where aerosol propellants are released. Remember the air may be safe to breathe, but when it goes through
a flame, chemical changes take place which may attack the water heater.
A secondary flue is not required. The water heater must not be installed indoors or in a confined space.
The water heater must be located to ensure that the location of the flue terminal complies with the
requirements of AS 5601 or AS/NZS 5601.1, as applicable under local regulations. As a guide the following
requirements are extracted from the Gas Installations Standard. The distances are measured along the wall
behind the water heater.
At least 300 mm between the top of the flue terminal
and the eaves.
At least 500 mm between the flue terminal and the
edge of any opening into the building, such as an
openable door or window, measured horizontally*.
At least 1500 mm between the top of the flue terminal
and the edge of any opening into the building, such as
an openable window, measured vertically.
At least 300 mm between the flue terminal and a
return wall or external corner, measured horizontally*.
At least 1500 mm between the flue terminal and any
opening into a building, in the direction of the flue
discharge.
At least 500 mm between the flue terminal and a fence, wall or other obstruction, in the direction of the
flue discharge.
Note: * If these horizontal distances cannot be achieved, AS/NZS 5601.1 states an equivalent horizontal
distance measured diagonally from the nearest discharge point of the flue terminal to the opening may be
deemed to comply. Check with the local regulator.
SAFE TRAY
Where damage to property can occur in the event of the water heater leaking, the water heater must be
installed over a safe tray. Construction, installation and draining of a safe tray must comply with
AS/NZS 3500.4 and all local codes and regulatory authority requirements.
RECESS INSTALLATION
The water heater can be installed recessed into a wall. A recess box (PN 299828) is available for such an
installation. Refer to the installation instructions which accompany the recess box kit for information on its
installation.
An additional rating label is supplied attached to the inside of the front cover of the water heater. This is for a
service person to access the water heater details when required. The rating plate on the side of the water
heater should be moved to or the information copied onto either the front panel of the water heater or to
another position which is visible when the water heater is installed so the householder can access the water
heater details when required.
Clearance Requirements
Continuous Flow Gas Water Heater

INSTALLATION –WATER HEATER
19
FROST PROTECTION
The water heater has a frost protection system. The frost protection system will protect the water heater from
damage, by preventing ice forming in the waterways of the water heater, in the event of freezing conditions
occurring.
The frost protection system will be rendered inoperable if electrical power is not available at the water heater.
Damage to the water heater caused by freezing of the pipe work to or from the water heater is not covered
under the Rheem warranty. Refer to AS/NZS 3500.4 for precautions to be taken for installations in frost
prone areas. The water heater is not suitable for installation in areas where the ambient temperature falls
below -20ºC (including wind chill factor).
The cold water line to the water heater must be insulated with suitable thickness insulation if freezing
conditions are likely to occur. The insulation must be fitted to the underside of the water heater and be
weatherproof and UV resistant if exposed.
MAINS WATER SUPPLY
Where the mains water supply pressure exceeds that shown in the table below, an approved pressure
limiting valve that does not have non return valve characteristics (such as an RMC PSL series valve) is
required and should be fitted as shown in the installation diagram (refer to page 22).
Model
W27
Relief valve setting
1000 kPa
Expansion control valve setting
850 kPa
Max. mains supply pressure
With expansion control valve
650 kPa
Without expansion control valve
800 kPa
Min. mains supply pressure *
160 kPa
* minimum water supply pressure required to achieve the rated flow
and performance
Notes:
It is not recommended to install this water heater with a low pressure water supply.
A minimum water supply pressure of 160 kPa is required to achieve the rated flow and performance of
the water heater.
If sludge or foreign matter is present in the water supply, it is recommended a suitable filter be
incorporated in the cold water line to the water heater.
This water heater is not suitable for connection to bore water or spring water unless a water treatment
device is fitted.
Refer to “Water Supplies”on page 12 for further information on water chemistry.
WATER TEMPERATURE DIAGRAMS
Note:Water initially discharged by this water
heater at start-up may be at a temperature of up
to 70°C before the water heater normalises to its
preset outlet temperature.
Temperature Limiting Devices –refer to “Hot
Water Delivery” on page 20.
Factory preset outlet temperature setting is:
874 series 60°C

INSTALLATION –WATER HEATER
20
HOT WATER DELIVERY
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 874 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.
The temperature limiting device used with a continuous flow gas water heater should have:
a specified „minimum temperature differential‟between the hot water inlet and the tempered water outlet
of no greater than 10°C, and
a specified „maximum permitted pressure variation‟in the supply between the hot water inlet and the
cold water inlet of no less than 15%.
Refer to the specifications of the temperature limiting device.
Where a temperature limiting device is installed adjacent to the water heater, the cold water line to the
temperature limiting device can be branched off the cold water line either before or after the isolation valve
and pressure limiting valve to the water heater.
If a pressure limiting valve is installed on the cold water line to the water heater and the cold water line to a
temperature limiting device branches off before this valve or from another cold water line in the premises,
then a pressure limiting valve of an equal pressure setting may be required prior to the temperature limiting
device.
LEGEND
Two Temperature Zones Using a Temperature Limiting Device