Rheem 491 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
Electric Domestic Water Heater
Model 491/492 (400L)

PATENTS
This water heater may be protected by one or more patents or registered designs
in the name of Rheem Australia Pty Ltd or Rheem New Zealand Limited.
TRADEMARKS
® Registered trademark of Rheem Australia Pty Ltd or Rheem New Zealand Limited.
TM Trademark of Rheem Australia Pty Ltd or Rheem New Zealand Limited.
Note: Every care has been taken to ensure the accuracy in preparation of this
publication. No liability can be accepted for any consequences,
which may arise as a result of its application.

3
CONTENTS
HOUSEHOLDER
This booklet contains important information about your
new water heater, including terms of the Rheem warranty.
We recommend you read pages 8 to 41,
and the terms of the Rheem warranty on pages 4 to 7.
The other pages are intended for the installer but may be of interest.
Warranty .......................................................................................4
About Your Water Heater............................................................8
Maintenance Requirements ......................................................14
Water Supplies...........................................................................17
Save A Service Call ...................................................................21
Installation..................................................................................24
Connections –Plumbing .................Error! Bookmark not defined.2
Connections –Electrical.........................................................377
Commissioning..........................................................................39
Draining The Water Heater .....................................................400
RHEEM NEW ZEALAND LIMITED www.rheem.co.nz
For Service Telephone [phone] NEW ZEALAND

4
RHEEM ELECTRIC DOMESTIC MAINS PRESSURE
WATER HEATER WARRANTY –NEW ZEALAND ONLY
ELECTRIC WATER HEATERS 491/492 MODELS
In addition to your legal right, in New Zealand Rheem New Zealand Limited
makes the following promise to the owner. We will repair or, if necessary, replace
a defective unit or part of it, which has failed due to faulty manufacture on the
following terms and conditions:
1. THE RHEEM WARRANTY –GENERAL
1.1 This warranty is given in respect of sales in New Zealand by Rheem New
Zealand Limited of 475 Rosebank Road Avondale Auckland 1026.
1.2 Rheem offer a trained and qualified national service network who will repair or
replace components at the address of the unit subject to the terms of the
Rheem warranty in New Zealand –contact your Rheem Service Centre on
0800 657 335.
1.3 For details about this warranty, you can contact your Rheem Service Centre in
New Zealand on 0800 657 335.
1.4 The terms of this warranty and what is covered by it are set out in sections 2
and 3 and apply to water heaters manufactured from 1st October 2018.
1.5 If a subsequent version of thiswarranty is published, the terms of that warranty
and what is covered by it will apply to water heaters manufactured after the
date specified in the subsequent version.
2. TERMS OF THE RHEEM WARRANTY AND EXCLUSIONS TO IT
2.1 The decision of whether to repair or replace a faulty component is at Rheem
New Zealand Limited’s sole discretion.
2.2 Where a failed component or cylinder is replaced under this warranty, the
balance of the original warranty period will remain effective. The replacement
does not carry a new Rheem warranty.
2.3 Where the unit is installed outside the boundaries of a metropolitan area,
defined by Rheem as further than 25 km from a Rheem Service Centre, the
cost of transport, insurance and travelling between the Rheem Service Centre
and the installed site shall be the owner’s responsibility.
2.4 Where the unit is installed in a position that does not allow safe or ready
access, the cost of that access, including the cost of additional materials
handling and/or safety equipment, shall be the owner’s responsibility. In other
words, the cost of dismantling or removing cupboards, doors, walls, roofs or
trap doors and the cost of any special equipment to bring the unit to floor or
ground level or to a serviceable position is not covered by this warranty.

RHEEM ELECTRIC DOMESTIC MAINS PRESSURE
WATER HEATER WARRANTY –NEW ZEALAND ONLY
5
ELECTRIC WATER HEATERS 491/492 MODELS
2.5 This warranty only applies to the original and genuine Rheem unit in its original
installed location and anygenuine Rheem replacement parts. It does not cover
any plumbing, gas fitting or electrical parts supplied by the installer, that are
not an integral part of the unit, e.g. pipe-work, pressure limiting valve, stop
valves, non-return valves, electrical switches, pumps and fuses.
2.6 The Rheem warranty does not cover faults that are a result of:
a) Accidental damage to the unit or any component, for example Acts of God
such as floods, storms, fires, lightning strikes and the like and Third party
acts or omissions.
b) Misuse or abnormal use of the unit.
c) Installation or use not in accordance with the Owner’s Guide and
Installation Instructions, New Zealand Building Code requirements or with
relevant statutory and local requirements including failure to install a
properly drained safe tray where required by the owners guide and
installations.
d) Connection at any time to a water supply that does not comply with the
water supply guidelines as outlined in the Owner’s Guide and Installation
Instructions, or poor water quality outside the limits specified in the owners
guide and installation instructions.
e) Repairs, attempts to repair or modifications to the unit by a person other
than Rheem Service or a Rheem Accredited Service Technician.
f) Faulty plumbing or faulty power supply.
g) Failure to maintain the unit in accordance with the Owner's Guide and
Installation Instructions.
h) Transport damage.
i) Fair wear and tear from adverse conditions (for example, corrosion).
j) Cosmetic defects.
2.7 If you require a call out and we find that the fault is not covered by the Rheem
warranty, you are responsible for Rheem Service Centre call out costs. If you
wish to have the relevant component repaired or replaced by Rheem that
service will be at your cost.

RHEEM ELECTRIC DOMESTIC MAINS PRESSURE
WATER HEATER WARRANTY –NEW ZEALAND ONLY
6
ELECTRIC WATER HEATERS 491/492 MODELS
2.8 Subject to any statutory provisions to the contrary, this warranty excludes any
and all claims however arising including under contract or tort for damage to
furniture, carpet, walls, foundations or any other consequential loss or
incidental expenses either directly or indirectly due to leakage from Rheem
unit, or due to leakage from fittings and/ or pipe work of metal, plastic or other
materials caused by water temperature, workmanship or other modes of
failure.
2.9 This warranty excludes to the extent permissible all implied warranties set out
in the Sale of Goods Act 1908 (New Zealand) and all guarantees set out in the
Consumers Guarantees Act 1993 (New Zealand) to the extent that the goods
are acquired for the purpose of resupply in trade consumption in the course of
a process of production or manufacture or repairing or treating in trade other
goods or fixtures on land.
3. WHAT IS COVERED BY THE RHEEM WARRANTY
FOR THE WATER HEATERS DETAILED IN THIS DOCUMENT
3.1 Rheem will repair or replace a faulty component of your unit if it fails to operate
in accordance with its specifications as follows:
What components
are covered
The period from the date
of installation in which
the fault must appear in
order to be covered
What coverage you receive
491/492 series models
All components
Year 1
Repair and/or replacement of the
faulty component, free of charge,
including labour.
The cylinder
(if the water heater
is installed in a
single-family
domestic dwelling)
Years 2 to 12
Replacement cylinder, free of
charge. Installation and repair
labour costs are the
responsibility of the owner.
The cylinder
(if the water heater
is not installed in a
single-family
domestic dwelling)
Years 2 & 3
Replacement cylinder, free of
charge. Installation and repair
labour costs are the
responsibility of the owner.

RHEEM ELECTRIC DOMESTIC MAINS PRESSURE
WATER HEATER WARRANTY –NEW ZEALAND ONLY
7
ELECTRIC WATER HEATERS 491/492 MODELS
4. ENTITLEMENT TO MAKE A CLAIM UNDER THIS WARRANTY
4.1 To be entitled to make a claim under this warranty you need to:
a) Be the owner of the unit or have consent of the owner to act on their behalf.
b) Contact Rheem New Zealand Limited Service Department without undue
delay after detection of the defect and, in any event, within the applicable
warranty period.
c) Return the faulty component or unit as directed by the Rheem New
Zealand Limited Service Department.
4.2 You are not entitled to make a claim under this warranty if your unit:
a) Does not have its original serial numbers or rating labels.
b) Is not installed in New Zealand.
5. HOW TO MAKE A CLAIM UNDER THIS WARRANTY
5.1 If you wish to make a claim under this warranty, you need to:
a) Contact Rheem New Zealand on 0800 657 335 and provide the owner’s
details, address of the unit, a contact number and date of installation of the
unit or if that’s unavailable, the date of manufacture and serial number
(from the rating label on the unit).
b) A Rheem Service Centre will arrange for the unit to be tested and
assessed on-site.
c) If Rheem determines that you have a valid warranty claim, Rheem will
repair or replace the unit in accordance with this warranty.
5.2 Any expenses incurred in the making of a claim under this warranty will be
borne by you.
6. THE CONSUMER GUARANTEES ACT 1993 (NEW ZEALAND)
6.1 Our goods come with guarantees that cannot be excluded under the Consumer
Guarantees Act 1993 (New Zealand). If the goods fail to comply with the
applicable guarantees set out under the Consumer Guarantees Act 1993 (New
Zealand) being the guarantee as to acceptable quality, the guarantee as to
correspondence with description or the guarantee as to repair and parts, or if
the goods fail to comply with any express guarantee given by Rheem, then you
are entitled to a replacement or refund and for compensation for any other
reasonably foreseeable loss or damage.
6.2 The Rheem warranty (set out above) is in addition to any rights and remedies
that you may have under the Consumer Guarantees Act 1993 (New Zealand).

8
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®491/492 series water heater you have chosen is suitable for either
indoor or outdoor installation.
Rheem®491/492 series models are available with either a single heating unit or
with twin heating units (refer to “Single Element Model” on page 11 and “Twin
Element Model” on page 11).
Water is stored in a vitreous enamel lined steel cylinder and heated by the
electric immersion heating unit. The thermostat controls the temperature.
Automatic safety controls are fitted to the water heater to provide safe and
efficient operation.
A Rheem®491/492 series water heater
have caps covering brass plugs on one
side of the tank. The plugs and caps
block off alternative connection points
and are not to be tampered with or
removed.
HOW HOT SHOULD THE WATER BE?
The water heater features an adjustable
thermostat, which allows you to choose
the most suitable temperature for your
hot water needs. Refer to “Temperature
Adjustment” on page 9.
A Rheem®491/492 series water heater
is temperature limited to deliver water
not exceeding 50°C to sanitary fixtures
used primarily for personal hygiene
purposes.
To meet the requirements of the
National Plumbing Standard the
temperature of the stored water must
not be below 60°C.
minimum thermostat setting
and minimum recommended
stored water temperature.
top heating unit thermostat
setting on a twin element
model (not adjustable)
maximum thermostat setting
491/492 series 400 models
maximum recommended
supply temperature to
bathrooms and ensuites

ABOUT YOUR WATER HEATER
9
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 also be required by regulations that an approved
temperature limiting device be fitted into the hot water pipe work to the bathroom
and ensuite when a Rheem®491/492 series water heater is installed. This will
keep the water temperature below 55°C at the bathroom and ensuite. The risk of
scald injury 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 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.
TEMPERATURE ADJUSTMENT
A Rheem®491/492 series water heater features a tradesperson adjustable
thermostat. This requires a licensed electrical worker to make any temperature
adjustments. The bottom thermostat (twin element models) has a maximum
temperature setting of 70°C and a minimum temperature setting of 60°C. The
top thermostat on a twin element model has a fixed setting of 60°C and cannot
be adjusted.
We advise you to have an authorised person adjust the thermostat to the lowest
temperature setting that meets your needs, especially if there are young children
or elderly people in your home. Refer to “Hotter Water Increases The Risk of
Scald Injury” on page 9.

ABOUT YOUR WATER HEATER
10
SAFETY
This water heater is supplied with a thermostat, an over-temperature cut-out and
a combination temperature pressure relief valve. 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 operation of the over-temperature cut-out on the thermostat indicates a
possibly 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.
If the electrical conduit to the water heater is damaged, it must be replaced by a
qualified person in order to avoid a hazard. Phone Rheem Service or their
nearest Rheem Service Centre to arrange for an inspection.
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.
WARNINGS
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.
This water heater uses 240 V AC power for the electrically operated
components. The removal of the front cover(s) will expose 240 V wiring. It
must only be removed by a qualified person.
For continued safety of this water heater it must be installed, operated and
maintained in accordance with the Owner’s Guide and Installation
Instructions.
MAINS PRESSURE
The water heater is designed to operate at mains pressure by connecting directly
to the mains water supply. If the mains supply pressure in your area exceeds
that shown on page 25, a pressure limiting valve must be fitted. The supply
pressure should be greater than 350 kPa for true mains pressure operation to be
achieved.

ABOUT YOUR WATER HEATER
11
SINGLE ELEMENT MODEL
This type of water heater has one heating
unit with its own thermostat, located at the
base of the water heater.
Continuous electricity supply
This type of connection is suited to
where the storage capacity is less than
the normal daily usage.
Off-Peak electricity supply
This type of connection will only allow
heating to occur during set hours. A
volume of water sufficient for the day’s
total use is heated and stored. This type
of heating will be more economical due
to reduced tariffs by the electricity
authority.
TWIN ELEMENT MODEL
This type of water heater has two heating units, each with its own thermostat.
One heating unit is at the base of the water heater and the other near the top.
Bottom heating unit
During normal operation this heating unit supplies all the hot water.
Top heating unit (Booster)
This heating unit only operates during
periods of high demand to provide an
additional supply of heated water.
Electrical connection
The two heating units are wired for non-
simultaneous operation, so that only one
heating unit can operate at a time. The
bottom heating unit is usually connected
to an Off-Peak (overnight) or time
controlled supply and the top heating
unit to a Continuous / Domestic supply.
Some electricity suppliers allow both
heating units to be metered at the Off-
Peak or controlled tariff.
NOTE: Power must be available to the top heating unit circuit at all times
for this water heater to operate as designed.

ABOUT YOUR WATER HEATER
12
PRECAUTIONS
Where damage to property can occur in the event of the water heater leaking,
the water heater must be installed in 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 safe tray must also meet the
requirements of Clause G12 of the New Zealand Building Code. AS/NZS 3500.4
and the NZBC also have particular requirements when a safe tray must be
installed.
The water heater must be maintained in accordance with the Owner’s Guide and
Installation Instructions. Refer to “Maintenance Requirements”on page 14 and
to “Anode Inspection and Replacement” on page 17.
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.
TO TURN OFF THE WATER HEATER
If you plan to be away from home for only a few nights, we suggest you leave
the water heater switched on.
If it is necessary to turn off the water heater:
Switch off the electrical supply at the isolating switch(s) to the water heater,
at the switchboard and adjacent to the water heater (if installed).
Close the cold water isolation valve at the inlet to the water heater.
TO TURN ON THE WATER HEATER
Open the cold water isolation valve fully on the cold water line to the water
heater.
Switch on the electrical supply at the isolating switch(s) to the water heater,
at the switchboard and adjacent to the water heater (if installed).
GOING ON HOLIDAY?
If you plan to be away from home for one or two nights, we suggest you leave
the water heater switched on. However, if you plan to stay away more than a few
nights, conserve energy by switching the water heater off at either the
switchboard or isolating switch (if one is installed).

ABOUT YOUR WATER HEATER
13
Note: When the electrical supply is switched back on, the water heater will take
some time to reheat the water. Depending upon the power supply connection,
hot water may not be available until the next day.
HOW DO I KNOW IF THE WATER HEATER IS INSTALLED CORRECTLY?
Installation requirements are shown on pages 24 to 31. The water heater must
be installed:
by a qualified person, and
in accordance with the installation instructions, and
to conform to Clauses G12 and H1 of the New Zealand Building Code, and
in compliance with Standards AS/NZS 3500.4, AS/NZS 3000 and all local
codes and regulatory authority requirements.
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 17.
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
pages 17 to 20.
HOW LONG WILL THE WATER HEATER LAST?
The water heater is supported by a manufacturer’s warranty (refer to page 4).
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 12.

14
MAINTENANCE REQUIREMENTS
MAJOR SERVICE EVERY FIVE YEARS
It is recommended a major service be conducted on the water heater every
five (5) years.
Warning: Servicing of a water heater must only be carried out by qualified
personnel. Phone your Rheem Service Centre.
Note: The major service and routine replacement of any components, such as
the anode and relief valve(s), 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 major service includes the following actions:
Replace the temperature pressure relief valve.
Inspect and flush the expansion control valve (if fitted). If required, replace
the valve.
Inspect and if required, replace the anode.
If the anode is not replaced, it should be replaced within five (5) years of this
service (refer to “Anode Inspection and Replacement” on page 18).
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.
Note: The water heater may need to be drained during this service. After the
completion of the service, the water heater will take some time to reheat the
water.

MAINTENANCE REQUIREMENTS
15
MINOR MAINTENANCE EVERY SIX MONTHS
It is recommended minor maintenance be performed every six (6) months. Minor
maintenance can be performed by the dwelling occupant.
The minor maintenance includes:
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 16.
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 15.
Check the drain line from the safe tray (if one is installed) is not blocked.
EXPANSION CONTROL VALVE
It is mandatory an expansion control valve is fitted to the cold water line to the
water heater to comply with Clause G12 of the New Zealand Building Code. 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.
Refer to “Minor Maintenance Every Six Months”on page 15. It is very important
the lever is raised and lowered gently. If water does not flow freely from the
drain line when the lever is lifted, then the water heater should be checked by
your Rheem Service Centre. The expansion control valve should be checked for
performance or replaced at intervals not exceeding five (5) years, or more
frequently in areas where there is a high incidence of water deposits.

MAINTENANCE REQUIREMENTS
16
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 22).
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 (6)
months. Refer to “Minor Maintenance Every
Six Months” on page 15.It is very
important the lever is raised and lowered
gently.
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 your Rheem Service Centre to arrange
for an inspection.
The temperature pressure relief valve should be replaced at intervals not
exceeding five (5) years, or more frequently in areas where there is a high
incidence of water deposits (refer to “Water Supplies” on page 17).
water
heater
drain
line
lift until water
flows from the
drain line –
lower gently

17
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.
ANODE
The vitreous enamel lined cylinder of the water heater is only covered by the
Rheem warranty when the total dissolved solids (TDS) content in the water is
less than 2500 mg/L and when the correct colour coded anode is used. If an
incorrect colour coded anode is used in the water heater, any resultant faults will
not be covered by the Rheem warranty. In addition, the use of an incorrect colour
coded anode may shorten the life of the water heater cylinder.
The correct colour coded anode must be selected and fitted to the water heater
in accordance with the following advice and the Anode Selection chart on
page 187 for the Rheem warranty to apply to the water heater cylinder.
Total Dissolved Solids
Anode colour code
0 –40 mg/L
Green
40 –150 mg/L
Green or Black
150 –400 mg/L
Black
400 –600 mg/L
Black or Blue
600 –2500 mg/L
Blue
2500 mg/L +
Blue (no cylinder warranty)
The changing of an anode must be carried out by a qualified person.
Note: Some water analysis reports may state the conductivity of the water rather
than the level of total dissolved solids. Conductivity, measured in microsiemens
per centimetre (µS / cm), is directly proportional to the TDS content of the water.
TDS, in mg / L, is approximately 70% of the conductivity in µS / cm.

WATER SUPPLIES
18
ANODE INSPECTION AND REPLACEMENT
The anode installed in your water heater will slowly dissipate whilst protecting
the cylinder. The life of the cylinder may be extended by replacing the anode.
For water supplies which are either softened or desalinated, or where the water
supply may alternate between a water tank and a reticulated public supply or
another supply, or where there is a variable supply (e.g. from a bore or public
reticulated supply from various water sources), the anode must be inspected
(and replaced if there is any sign of depletion) within six (6) years of installation,
and within every six (6) years thereafter.
For all water supplies, if the anode is not replaced during a major service (refer
to “Major Service Every Six Years”on page 14) then in any event, the anode
must be replaced at 12 years.
CAUTION
If the water supply has a TDS greater than 150 mg/L and a green anode has not
been changed to a black anode, or if the TDS is greater than 600 mg/L and the
anode has not been changed to a blue anode, there is the possibility the anode
may become overactive and hydrogen gas could accumulate in the top of the
water heater during long periods of no use.
If, under these conditions, the water heater has not been used for two or more
weeks the following procedure should be carried out before using any electrical
appliances (automatic washing machines and dishwashers) which are
connected to the hot water supply.
The hydrogen, which is highly flammable, should be vented safely by opening a
hot tap and allowing the water to flow. There should be no smoking or naked
flame near the tap whilst it is turned on. Any hydrogen gas will be dissipated.
This is indicated by an unusual spurting of the water from the tap. Once the water
runs freely, any hydrogen in the system will have been released.
(3570)
Green
150
2500
600
400
TOTAL DISSOLVED SOLIDS (TDS) mg/L
(CONDUCTIVITY - μS/cm)
(215)
(570)
(860)
Black
40
(60)
Blue
Blue
ANODE SELECTION
Above 2500 mg/L,
no warranty applies
to a vitreous-
enamel-lined water
heater cylinder
Warranty applies to a vitreous-enamel-lined
water heater cylinder if the correct coloured
anode is used for the TDS of the water

WATER SUPPLIES
19
SATURATION INDEX
The saturation index is used as a measure of the water’s corrosive or scaling
properties. The saturation index figures stated are calculated using a water
temperature of 80°C.
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 sheathed heating unit. A
corrosion resistant heating unit must be used for the Rheem warranty to apply to
the heating unit.
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
after the non-return valve to protect and for the Rheem warranty to apply to the
temperature pressure relief valve and water heater cylinder.
Where the saturation index exceeds +0.80, the Rheem warranty does not apply
to a standard watts density heating unit. A low watts density heating unit must be
used for the Rheem warranty to apply to the heating unit.
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 on page 19. Refer to the cold water
connection detail on page 32 for the position of the expansion control valve.
Contact your Rheem Service Centre if a replacement heating unit is required.
+0.4 +0.80-1.0
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 sheathed heating unit
SATURATION INDEX (SI)
ELECTRIC WATER HEATERS
WITHIN WARRANTY
SPECIFICATION
SATURATION INDEX
(calculated @ 80°C water temperature)
no warranty applies to a:
-standard watts density heating unit
very corrosive very scaling
scaling
corrosive

WATER SUPPLIES
20
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 water heater
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
Total Dissolved Solids (TDS) > 2500 mg/L
water heater cylinder
Total Dissolved Solids (TDS)
not suitable for anode type
water heater cylinder
Saturation Index (SI) < -1.0
copper sheathed heating unit
Saturation Index (SI) > +0.4
(if expansion control valve is not fitted)
water heater cylinder
temperature pressure relief valve
Saturation Index (SI) > +0.8
standard watts density heating unit