Rheem Optima Technical Document

This water heater must be installed and serviced by an authorised person.
Please leave this guide with the householder.
Owner’s Guide
and
Installation Instructions
Electric Domestic
Water Heater

PATENTS
This water heater may be protected by one or more patents or registered designs
in the name of Rheem Australia Pty Ltd.
TRADEMARKS
® Registered trademark of Rheem Australia Pty Ltd.
TM Trademark of Rheem Australia Pty Ltd.
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.

CONTENTS
About Your Water Heater ............................................................. 4
Regular Care .................................................................................. 9
Water Supplies ........................................................................... 11
Save A Service Call ................................................................... 15
Installation .................................................................................. 18
Connections – Plumbing ........................................................... 25
Connections – Electrical ............................................................. 28
Commissioning .......................................................................... 31
Draining The Water Heater ....................................................... 34
Warranty ..................................................................................... 36
HOUSEHOLDER - We recommend you read pages 4 to 17.
The other pages are intended for the installer but may be of interest

4
ABOUT YOUR WATER HEATER
MODEL TYPE
The Rheem® water heater you have chosen is an Optima™ model.
The Optima model has a temperature adjusting knob on the lower front of
the water heater. Optima models are available with either a single heating unit
or with twin heating units. (refer to “Single Element Model” on page 7 and
“Twin Element Model” on page 7).
The water heater can be installed indoor or outdoor. Optima models have an
extended warranty (refer to the warranty on page 36).
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.
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 19, a pressure limiting valve must be fitted. The
supply pressure should be greater than 350 kPa for true mains pressure
operation to be achieved.
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 5.
To meet the requirements of the
G12 Building Code the temperature of
the stored water must not be below 60°C.
maximum thermostat setting
Optima models
minimum thermostat setting
and minimum recommended
stored water temperature.
top heating unit thermostat
setting on a twin element
model (not adjustable)

ABOUT YOUR WATER HEATER
5
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 an Optima 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
An Optima water heater features a user adjustable
thermostat, which allows you to choose the most
suitable temperature for your hot water needs. To
adjust the temperature, push in the child resistant
knob and turn anticlockwise to decrease or
clockwise to increase the temperature setting. The
Optima has a minimum temperature setting of 60°C
and a maximum temperature setting of 75°C.

ABOUT YOUR WATER HEATER
6
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.
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 an authorised or qualified person.
Take care not to touch the power plug on a water heater fitted with a power
supply cord and plug with wet hands.
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 an authorised or
qualified person.
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 warranty can become void if relief valves or other safety devices are
tampered with or if the installation is not in accordance with these
instructions.

ABOUT YOUR WATER HEATER
7
SINGLE ELEMENT MODEL
This type of water heater has one heating
unit with its own thermostat. The heating
unit is 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 electricity supply and the
top heating unit to a continuous 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
8
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 to the water heater.
Unplug the power supply cord from the power outlet (power supply cord
model only).
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.
Plug in the power supply cord at the power outlet (power supply cord model
only).
Switch on the electrical supply at the isolating switch to the water heater.
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.
HOW DO I KNOW IF THE WATER HEATER IS INSTALLED CORRECTLY?
Installation requirements are shown on pages 18 to 26. The water heater must
be installed by an authorised person and the installation must comply with
National Standards AS/NZS 3500.4, AS/NZS 3000 and all local codes and
regulatory authority requirements. The installation must conform with the
New Zealand Building Code.
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 cylinder and fittings. If
you are in a known harsh water area you must read page 11. If you are not
sure, have your water chemistry checked against the conditions described on
page 11.
HOW LONG WILL THE WATER HEATER LAST?
There are a number of factors that will affect the length of service the water
heater will provide. These include the water chemistry, the water pressure, the
water temperature (inlet and outlet) and the water usage pattern. However,
your water heater is supported by a comprehensive warranty (refer to page 36).

9
REGULAR CARE
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 16).
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.
DANGER: Failure to do this may
result in the water heater cylinder
failing, or under certain circumstances,
exploding.
If water does not flow freely from the
drain line when the lever is lifted, then
the water heater should be checked by
a Rheem Service Centre.
The temperature pressure relief 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 (refer to “Water Supplies” on
page 11).
water
heater
drain
line
lift until water
flows from the
drain line –
lower gently

REGULAR CARE
10
TEMPERATURE LIMITING VALVE
The valve should be checked for performance every twelve months. This can
be performed by measuring the water temperature from a hot tap with a
thermometer. If the water is being delivered at a temperature exceeding 55°C,
phone a Rheem Service Centre.
The 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 11). Failure to do this may result in water at a
temperature up to 70°C being delivered at the hot tap, increasing the risk of
scald injury.
EXPANSION CONTROL VALVE
An expansion control valve must be 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.
GENERAL MAINTENANCE
The jacket of the water heater can be cleaned with a soft cloth and warm mild
soapy water on a 3 monthly interval in coastal areas. Under no circumstances
should abrasive materials or powders be used.

11
WATER SUPPLIES
This water heater must be installed in accordance with this advice to be
covered by the 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 water heater warranty to apply.
ANODE
The vitreous enamel lined cylinder of the water heater is only covered by
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 installed. The use of an
incorrect colour coded anode will void the cylinder warranty and 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 11 for 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 anodes must be carried out by a plumber or authorised service
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
12
CONDUCTIVITY - µS/cm
TOTAL DISSOLVED SOLIDS & CONDUCTIVITY
(vitreous enamel lined water heater cylinder)
40 150 400 600 TOTAL DISSOLVED SOLIDS (TDS) - mg/L
ANODE SELECTION
warranty applies to a vitreous enamel lined water heater cylinder if the
correct coloured anode is used for the TDS / conductivity level of water
2500
3570
no warranty
applies
to a vitreous
enamel lined
water heater
cylinder
Blue
Black
Green
60 215 570 860
0
0
Blue
ANODE INSPECTION
The anode installed in your water heater will slowly dissipate whilst protecting
the cylinder. The life of the water heater cylinder may be extended by arranging
for an authorised person to inspect the anode and replace if required.
The suggested time after installation when the anode should be inspected is:
Optima 10 years
For water supplies which are either softened, desalinated or where the water
supply may alternate between a water tank and a reticulated public supply or
another supply, it is recommended the anode be inspected 3 years earlier than
shown (refer to “Anode” on page 11).
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.

WATER SUPPLIES
13
SATURATION INDEX
The saturation index 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 warranty does not apply to a copper sheathed heating unit. A corrosion
resistant heating unit must be used for 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 warranty to apply to the
temperature pressure relief valve and water heater cylinder.
Where the saturation index exceeds +0.80, warranty does not apply to a
standard watts density heating unit. A low watts density heating unit must be
used for 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 13. Refer to the cold water
connection detail on page 27 for the position of the expansion control valve.
Contact Rheem Service Centre if a replacement heating unit is required.
+0.4 +0.80
very corrosive very scaling
scaling
corrosive
-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

WATER SUPPLIES
14
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 warranty
to apply.
SUMMARY OF WATER CHEMISTRY ADVICE AFFECTING WARRANTY
The warranty of this water heater does not apply on the components listed
below if the water heater is connected at any time to a water supply with water
chemistry of:
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

15
SAVE A SERVICE CALL
Check the items below before making a service call. You will be charged for
attending to any condition or fault that is not related to the manufacture or
failure of a part.
NOT ENOUGH HOT WATER (OR NO HOT WATER)
Is the electricity switched on?
Inspect the isolating switch marked “HOT
WATER” or “WATER HEATER” at the
switchboard and the isolating switch (if one
is installed) near the water heater and
ensure they are turned on.
Note: Check the electricity supply to which
the water heater is connected. If on an Off-
Peak or time controlled electricity supply,
remember heating hours are restricted
(refer to “Off-Peak Electricity Supply” on
page 7).
Check the fuse marked “HOT WATER” or “WATER HEATER” at the
switchboard.
Twin element water heaters
A twin element non-simultaneous model must have power available to the
top heating unit circuit at all times for the water heater to operate as
designed.
Are you using more hot water than you think?
Is one outlet (especially the shower) using more hot water than you think?
Very often it is not realised the amount of hot water used, particularly when
showering. Carefully review the family‟s hot water usage. Have your
plumber fit a flow control valve to each shower outlet to reduce water usage.
Temperature pressure relief valve running
Is the relief valve discharging too much water? (Refer to “Temperature
Pressure Relief Valve Running” on page 16).
Thermostat setting
Ensure the thermostat setting is appropriate. You may choose to adjust
the thermostat upwards to gain additional hot water capacity.
Refer to “temperature Adjustment” on page 5
Warning: Hotter water increases the risk of scald injury.

SAVE A SERVICE CALL
16
Water heater size
Do you have the correct size water heater for your requirements? The sizing
guide in the Rheem sales literature and on the Rheem website
(www.rheem.co.nz) suggests average sizes that may be needed.
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 9). 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 switchboard. Phone a Rheem
Service Centre

SAVE A SERVICE CALL
17
EXPANSION CONTROL VALVE RUNNING
If an expansion control valve is fitted in the cold water line to the water heater
(refer to page 27) 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 ELECTRICITY BILLS
Should you at any time, feel your electricity account is higher than expected,
we suggest you check the following points:
Is the relief valve running excessively?
Refer to “Temperature Pressure Relief
Valve Running” on page 16.
Is one outlet (especially the shower)
using more hot water than you think?
Refer to “Not Enough Hot Water” on
page 15.
Is there a leaking hot water pipe,
dripping hot water tap, etc?
Even a small leak will waste a
surprising quantity of hot water and
electricity. Replace faulty tap washers,
and have your plumber rectify any
leaking pipe work.
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 electricity retailer
since your previous account?
ELECTRICITY TARIFFS
The electricity tariff to which your water heater is connected will determine the
overall operating cost of the system. It is important you are aware of this tariff,
i.e. Off-Peak (overnight) or time controlled supply, Extended Off-Peak
(overnight and day) or Extended time controlled supply, Domestic / Continuous.
For types of tariffs, refer to “Single Element Model” on page 7 and “Twin
Element Model” on page 7.
IF YOU HAVE CHECKED ALL THE FOREGOING AND STILL BELIEVE YOU
NEED ASSISTANCE, PHONE A RHEEM SERVICE CENTRE.

18
INSTALLATION
THIS WATER HEATER IS NOT SUITABLE FOR POOL HEATING
The installation must comply with the requirements of AS/NZS 3500.4,
AS/NZS 3000 and all local codes and regulatory authority requirements. In New
Zealand, the installation must conform with the New Zealand Building Code.
All packaging materials must be removed from the water heater prior to its
installation. This includes the removal of the cardboard base of the carton from
the underside of the water heater.
WATER HEATER LOCATION
This water heater is suitable for either outdoor or indoor installation (a model
with a supply cord and plug is suitable for indoor installation only). Whether
located outdoor or indoor, the water heater should be installed close to the
most frequently used outlet and its position chosen with safety and service in
mind.
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 temperature pressure
relief valve lever is accessible and the
front cover, thermostat, heating unit
and if fitted, the side cover and
temperature limiting valve can be
removed for service.
You must be able to read the information on the rating plate. If possible leave
headroom of one water heater height so the anode can be inspected or
replaced. Remember you may have to take the entire water heater out later for
servicing.
It is recommended the water heater be installed at ground or floor level and
must stand vertically upright. The base of the water heater is made of corrosion
resistant material, and it may be placed directly in contact with the supporting
surface. It is not necessary to allow for free air circulation under the base of the
water heater.
Note: The water heater should not be placed in direct contact with a concrete
surface that is less than two months old and not fully cured as this may attack
the metal coating of the water heater base. A moisture barrier should be used
between the two surfaces in this instance.

INSTALLATION
19
Remember all local authorities have regulations about putting water heaters
into roof spaces.
SAFE TRAY
It is a requirement of AS/NZS 3500.4
that for a new installation, a water
heater be installed in a safe tray where
in the event of a leak, property may
otherwise be damaged. Construction,
installation and draining of a safe tray
must comply with the abovementioned
Standard.
MAINS WATER SUPPLY
Where the mains water supply pressure exceeds that shown in the table below,
an approved pressure limiting valve is required and should be fitted as shown
in the installation diagram (refer to diagram on page 27).
Model
025 to 160
250 to 400
Relief valve setting
1400 kPa
1000 kPa
Expansion control valve setting*
1200 kPa
850 kPa
Max. mains supply pressure
With expansion control valve
950 kPa
650 kPa
Without expansion control valve
1120 kPa
800 kPa
* Expansion control valve not supplied with water heater
TANK WATER SUPPLY
If the water heater is supplied with water from a tank supply and a pressure
pump system is not installed, then the bottom of the supply tank must be at
least 1 m above the highest point of the hot water plumbing system, including
the water heater. Care must be taken to avoid air locks. The cold water line to
the water heater should be adequately sized and fitted with a full flow gate
valve or ball valve.

INSTALLATION
Feet for Rheem Externally Mounted Cylinders
Optima 180, 300 and 400L Mains Pressure Water Heaters (3 pieces)
Outside diameters
180 model – 488mm
300 model – 580mm
400 model – 690mm
Feet are 50mm in from edge of cylinder
Installation options:
1. Push tags into soft concrete at correct points according to cylinder diameter
2. Cut off tags and use a blob of construction adhesive to hold feet in place at
correct points according to cylinder diameter
3. Cut off tags and screw feet into place on wooden platform at correct points
according to cylinder diameter
Note: It is important that only three feet are used to avoid “rocking” and that the
feet are positioned at 50mm from outside edge of cylinder to outside edge of feet.
317952A-01
20