Rheem 441 Series Operating instructions

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Rheem Australia Pty Ltd ABN 21 098 823 511
SERVICE INSTRUCTIONS
Lazer 441, 451, 741, 751, 761,
771, 781 & 791 Series
TM001
Revision: AD
Issued: Jan 14
Lazer 1 & 2
Silhouette
(Designer Series)
Classic
(Modular Series)
Silhouette
(Modular Series)
441 Series
761 Series
771 Series
791 Series
451 Series
781 Series
741 Series
751 Series
First Issued: May 1987

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions
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CONTENTS
INTRODUCTION .....................................................................................................................3
SAFETY WARNING.................................................................................................................3
MODEL IDENTIFICATION.......................................................................................................3
SPECIFICATIONS...................................................................................................................4
PREVENTATIVE MAINTENANCE ..........................................................................................5
OPERATION............................................................................................................................6
Electronic Controller Operating Modes.................................................................................6
COMPONENTS AND THEIR FUNCTIONS.............................................................................7
INSTALLATION NOTES..........................................................................................................8
WIRING DIAGRAMS ...............................................................................................................9
741/751 (2.5L - 40L) .............................................................................................................9
761, 791 & 771/781 (2.5L –40L) ........................................................................................10
FAULT FINDING....................................................................................................................11
General Fault Finding Chart................................................................................................11
Mode 1 Fault Finding..........................................................................................................12
Component Tests 1 - 4 ....................................................................................................13
Mode 2 Fault Finding..........................................................................................................14
Component Tests 5 - 8 .......................................................................................................15
Mode 3 & 4 Fault Finding....................................................................................................16
LAZER BOILING WATER UNITS AT HIGH ALTITUDES......................................................17
How to Adjust the Temperature Setting of the Controller (ECB).........................................17
ELECTRICAL IN-SERVICE TESTING...................................................................................18
ACCESSING COMPONENTS...............................................................................................19
COMPONENT REPLACEMENT............................................................................................20
Water Temperature Sensor (Thermistor)............................................................................20
DOCUMENT REVISION HISTORY.......................................................................................27

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions
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INTRODUCTION
The information provided in these instructions is based on the Rheem Lazer Boiling Water
Unit being installed in accordance with the installation instructions provided with each unit.
Should you require further technical advice on the Rheem Lazer Boiling Water Unit, contact
your nearest Rheem Australia Service Office where all genuine replacement parts are also
available.
SAFETY WARNING
The purpose of this Service Manual is to provide sufficient information to allow a person with
the skills as required by the controlling Regulatory Authorities to carry out effective repairs in
the minimum of time.
Safety precautions or areas where extra care should be observed when conducting tests
outlined in this service manual are printed in bold italics. Take care to observe the
recommended procedure.
Certain diagnostic procedures outlined in these Service Instructions require
“live” testing of certain components. An RCD should be installed between the
power point and 3-pin cord of the water heater whilst conducting the tests.
MODEL IDENTIFICATION
The identification (model) number is designed to convey detailed information about the
heater to which it is attached. Lazer Boiling Water Units are interpreted thus:
7
7
1
015
7 - Automatic Operation
4 & 7 - White enamel jacket
5 & 8 - S/Steel jacket
6 & 9 - Plastic Jacket, Silhouette
1 - Single heating unit
2 - Double heating unit
025 = 2.5 litre capacity
045 = 4.5 litre capacity
050 = 5.0 litre capacity
075 = 7.5 litre capacity
150 = 15 litre capacity
250 = 25 litre capacity
400 = 40 litre capacity
SERIAL NUMBER 741/751 Series
The serial number incorporates the date of manufacture as thus:
02
87
125
Month of Manufacture
Year of Manufacture
Serial Number
SERIAL NUMBER 771/781, 761 & 791 Series
The serial number indicates the country code AU for Australia and a sequential build number.
The date of manufacture is listed on the rating plate inside the jacket by the month and year
i.e. SEP 1999

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SPECIFICATIONS
Capacity
Litres
Model
Heating Element
Input (kW)
Load & Wiring
Type
Electrical Supply
Inlet Water
Pressure (kPa)
Inlet & Outlet
Connection
Min
Max
2.5
741025
1 x 2.4
10 amp
3-pin plug
230/240 VAC
50Hz
55
1000
R½/15
771025
50
761025
20
791025
50
4.5
741045
1 x 2.4
10 amp
3-pin plug
230/240 VAC
50Hz
55
1000
R½/15
5.0
771050
1 x 2.4
10 amp
3-pin plug
230/240 VAC
50Hz
50
1000
R½/15
761050
20
791050
50
7.5
741075
751075
1 x 2.4
10 amp
3-pin plug
230/240 VAC
50Hz
55
1000
R½/15
771075
781075
50
761075
20
791075
50
15
741150
751150
1 x 2.4
10 amp
3-pin plug
230/240 VAC
50Hz
55
1000
R½/15
771150
781150
75
25
741250
751250
1 x 3.6
15 amp
circuit
230/240 VAC
50Hz
200
1000
R½/15
771250
781250
75
40
741400
751400
1 x 4.6
20 amp
circuit
230/240 VAC
50Hz
200
1000
R½/15
771400
781400
100

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PREVENTATIVE MAINTENANCE
It is suggested for peak performance that the Boiling Water Unit be serviced every six
months.
Servicing must be performed by suitably qualified persons.
Hot surface or liquid. Personal Protective Clothing (PPE) shall be worn to
reduce the risk of burns or scalding.
1. Check the inlet strainer located inside the water inlet connection to ensure it is clean and
not blocked with foreign matter. If an additional auxiliary filter is fitted, such as in areas of
poor water quality check to ensure it is also clean and not blocked with foreign matter.
2. Check for signs of excessive corrosion on jacket and internal panels. Corrosion can be
indicative that a leak is present.
3. Check for leaks at all BWU fittings.
4. Check the vent line to ensure it is not blocked with foreign matter. It is imperative that
the vent line does not become blocked as the BWU is not designed to be
pressurised.
5. Isolate power and check all electrical connections for signs of overheating due to poor
connection.
6. Conduct an electrical in-service test. (Refer to page 18).
7. Check tap for signs of leaking & excessive dripping after operation (clean or replace if
required.

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OPERATION
IMPORTANT: High altitude will affect the Lazer Boiling Water Unit operation. Refer to
page 17 for more details
To commission water heater from empty:
Turn on water supply first
Turn on 240V supply, solenoid will open and filling will commence.
Filling will continue until the water reaches the WLS low-level probe.
Filling will stop and heating will commence until water reaches 97ºC.
Heating continues and filling re-commences and continues until water temperature
drops to 93ºC. Each time the solenoid valve closes the WLS high level is checked.
This process repeats itself until the water level reaches the WLS high-level probe, at
which time the solenoid closes and the heating unit is switched off when water
temperature reaches 97ºC.
From there on the heating unit will cycle to maintain water temperature between 93
and 97ºC.
The drawing off of boiling water will cause the solenoid to open and deliver cold water
on to the WTS which will in turn cause heating to commence.
The continuous drawing of water will cause the solenoid to close after 25 seconds;
ensuring water temperature is not continually reduced.
Electronic Controller Operating Modes
Mode 1. Empty
When water level is below the WLS low-level probe the heating unit will turn OFF, and the
solenoid valve will open to allow water to enter. When water level reaches the WLS low-level
probe, a delay of 2 seconds will elapse before the solenoid closes and heating commences.
Mode 2. Not Full
Continuing from Mode 1, the heating unit will have power on throughout Mode 2. While it is
heating, small quantities of water (approx. 100mL per cycle) are admitted through the
solenoid each time the water temperature is sensed at 97ºC.
The solenoid will:
Open to fill at 97ºC
Close at 93ºC
The solenoid cycle time will depend on the delay between cold-water entry and the sensing
of 93ºC, which is directly related to:
Temperature of inlet water.
Pressure of inlet water.
Capacity of the Lazer Boiling Water Unit.
Water level in the Lazer Boiling Water Unit
Water temperature should not drop below 93ºC throughout the fill cycle. Each time the
solenoid closes, the WLS high- level probe is activated and, if found to be covered with water
the ECB will change to Mode 3.

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Mode 3. Full
When water has covered the WLS high-level probe the solenoid will close and heating will
continue until a temperature of 97ºC is attained. The solenoid will open again for a split
second at this time.
Thereafter the solenoid opens only when the water level falls below the WLS high- level
probe.
Heating will continue to cycle ON and OFF between 93 and 97ºC.
The drawing of water from the tap will return the ECB to Mode 2.
During continuous drawing of water the solenoid will close after being open for 25
seconds.
Draining of all water will return the ECB to Mode 1.
Mode 4. Over temperature Cut Out (OTC)
The OTC mode will activate when the solenoid remains open for longer than 25 seconds in
Mode 2.
Once activated the OTC will switch OFF power to the solenoid and heating unit and remain in
this state until the water temperature drops below 93ºC. At this temperature the ECB will
switch back to Mode 2.
The OTC mode is not temperature activated and will not prevent continuous boiling of the
Lazer.
COMPONENTS AND THEIR FUNCTIONS
ELECTRONIC CONTROL BOX (ECB): A box containing a transformer, relay and electronic
PC board which provides the logic to monitor and control water level and temperature.
An over temperature function is incorporated to prevent the unit boiling dry. The wiring
terminals are 240 volt and 0 to 24 volt; therefore it is essential to connect all wires to the
correct positions.
WATER LEVEL SENSOR (WLS): An insulated stainless steel probe that monitors:
Low water level to ensure the heating element cannot operate unless covered by
water
High water level to ensure the maximum water level is not exceeded.
Damage to the probe insulation will cause the heater to malfunction.
SOLENOID VALVE / INLET FILTER: A 12-volt solenoid for 741/751 series with an inline
filter attached is located in front of the inner tank at the top of the water heater.
A 24-volt solenoid for 761,771/781, 791 series with an inline filter attached is located on the
lower left hand side of the water heater.
The operation is ON or OFF, but because of its small orifice size water hammer is not a
problem.
HEATING UNIT / SENSOR PROBE: A square flanged heating unit, bent at 90º on some
units to suit the width of the tank, incorporating a sensor probe centrally located between the
element loop.

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TEMPERATURE SENSOR (WTS): A thermistor is inserted inside the probe of the heating
unit and monitors water temperature to maintain water at near boiling point.
OVERFLOW / VENT: The outlet of this pipe must be to atmosphere for the following
reasons:
To allow air to escape while filling
To allow excess water to escape
To allow steam to escape while heating
To prevent inner tank collapse when draining
INSTALLATION NOTES
The Lazer boiling water unit is not weatherproof. External locations must be protected
from the weather and freezing conditions.
MOUNTING POSITION: Minimum clearances required for servicing are 350mm clear above
the top and to the right for 741/751 series and 150mm clear above the top and to the right for
761, 771/781 and 791 series. Refer to installer to correct if clearances are less than required.
OVERFLOW/VENT: A drain line discharging to the atmosphere with a continuous fall, not
exceeding 1 metre and with not more than 3 bends is required. The point of discharge should
be where the user can see it, but not cause annoyance or injury if water or steam is
discharged.
A drain line not meeting these requirements must be installed with an air-break (tundish).
WATER SUPPLY: The Lazer Boiling Water Unit is not a pressurized appliance. An AIR-
BREAK is incorporated into the internal filler pipe. Connect only to a cold water supply with a
constant pressure above the minimum supply pressure as specified in the SPECIFICATION
TABLE on page 4.
The maximum supply pressure shall not exceed 1000kPa for all models. An approved
stopcock is required for servicing purposes in the cold water supply line before the Lazer
Boiling Water Unit.
IMPORTANT:
Non-return valves or stopcocks incorporating a non-return valve MUST NOT BE
INSTALLED in the water supply connection for 741, 751and 761 series.
771, 781 and 791 series have a non-return valve fitted within the water heater.
DO NOT CONNECT TO A HOT WATER SUPPLY.
HOT WATER TAP: The tap is supplied with a chrome plated brass extension piece on
741/751 and 771/781 series. A 29mm A/F nut allows the tap to be aligned to a vertical
position.
On 761 and 791 series the tap is a “Rocker” type and is already installed for use.
The tap will drain all the contents of the Lazer Boiling Water Unit on some 741/751 series,
and therefore expose the heating unit to the air.
DO NOT:
Over-tighten tap into tank.
Remove the tap to service heating unit.

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ELECTRICAL CONNECTION: All Lazer Boiling Water Units are designed for 220/240 volt 50
Hertz electrical supply. Installations that cannot achieve the specified supply current, i.e.
private generators should be avoided. The internal wiring is designed to suit the load rating of
the heating unit stated on the RATING LABEL found inside the jacket.
DO NOT FIT A HEATING UNIT OF HIGHER RATING THAN SPECIFIED ON THE
RATING LABEL.
Lazer Boiling Water Units with 10amp load are supplied with a 3-pin plug. A licensed
electrician must wire units of 15amp capacity to a suitable supply.
WIRING DIAGRAMS
741/751 (2.5L - 40L)
2.5L -15L
25L - 40L

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761, 791 & 771/781 (2.5L –40L)
ECB
2.4kW
Element
Solenoid
761- 791 - 771/781 Series
2.5L - 15L
Phase Element Neutral Earth
Ready Ground Vp Low High Solenoid- Solenoid+ Sensor- Sensor+
LED
Board
P
E
N
Terminal
Block
Note:
ECO not fitted
on 15L models
WLS
R B
BL
RR
761 & 791
models only
G
R
WBL WB/W
BL
R
BR
G
BL
ECB
3.6kW - 25L
4.6kW - 40L
Element
Solenoid
771/781 Series
25 - 40L
Phase Element Neutral Earth
Ready Ground Vp Low High Solenoid- Solenoid+ Sensor- Sensor+
P
E
N
Terminal
Block
WLS
RR
G
WBL WB/W
BL
R
BR
G
BL
BR
BR
Relay
BL
B=Black
BL=Blue
BR=Brown
G=Green
W=White
R=Red
B/W=Black/White

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FAULT FINDING
It is possible to independently test individual components of the Lazer Boiling Water Unit,
however it is strongly recommended that this Test Procedure be followed irrespective of a
suspected malfunctioning component.
A failed or malfunctioning component may be the result of incorrect installation, faulty or
intermittent services, i.e. large voltage or water pressure fluctuations, water filtration units or
non-return valves in the water supply line or, incorrectly installed overflow/vent pipes.
Prior to commencing this Procedure ensure that the water pressure and electrical
supply meet the required specification for the Lazer boiling water unit outlined on
page 4.
General Fault Finding Chart
Disconnect power and
isolate water supply
Remove the jacket front or
access covers
Drain tank completely via drain
plug or tap Water at elevated temperatures may be present when draining, care should be taken to prevent scalding
Refit drain plug,
reconnect power and
restore water supply
Mode 1 diagnosis
NO
YES
NO
YES
Mode 2 diagnosis
NO
YES
NO
NO
Over temperature
mode diagnosis
YES
YES
NO
YES
Mode 3 diagnosis
NO
Normal OperationYES
Is the water
solenoid open? 1
Water solenoid closes
after a period?
Element
commences heating? 2
Solenoid alternates
operation until upper
water level reached,
element remains on
continuously?
Was the solenoid
open for longer than 25
seconds?
4
2
Mode 2 diagnosis
Element de-energized
after a period?
3
Element cycles to
maintain water
temperature?

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Mode 1 Fault Finding
YES YES
NO Repair broken strap or wiringNO
Disconnect the plug
from the water level
probe
NO
YES
YES
Isolate power before checking
the water level probe connection
Clean connection or replace
wiring.
Retest operation
NO
YES
Replace ECB
Retest operation
NO
Clean or replace water level
probe
Restest operation
YES
NO
NO
YES
Replace ECB
Retest operation
YES
Replace ECB and solenoid
valve
Retest operation
NO
YES
Replace solenoid valve
Retest operation
NO
1
Is the solenoid open? Does the solenoid close? 2
Mode 2 Diagnosis
Is there continuity of the
earth strap from the tank
to the ECB?
TEST 1
2.1
Does the solenoid open? Is the connection to the water level probe clean
and tight?
Is scale built up on probe
wires or body?
TEST 2
Is the supply voltage from
the ECB correct?
TEST 3
Is the resistance of the
solenoid valve correct?
TEST 4
2
Mode 2 Diagnosis
Is the resistance of the
solenoid valve correct?
TEST 4

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Component Tests 1 - 4
Test 1
Test 2
Normal resistance between the tank and the earth
point on the ECB is 0 ohms (dead short) when
measured with a multimeter on the x1 resistance
scale.
Normal resistance between the high level
probe wire and low level probe wire should
be infinity (open circuit) when measured with
a multimeter on the x10M resistance scale.
Test 3
Test 4
Install RCD and exercise caution when
conducting live tests
741/751 series
Normal voltage at the solenoid under load should
be between 6 and 12 volts when measured with a
multimeter on the DC voltage scale.
761, 771/781 and 791 series
Normal voltage at the solenoid under load should
be between 8 and 24 volts when measured with a
multimeter on the DC voltage scale.
741/751 series
Normal resistance of the solenoid coil should
be 23 ohms +/- 5% when measured with a
multimeter on the x1 resistance scale.
761, 771/781 and 791 series
Normal resistance of the solenoid coil should
be 55 ohms +/- 5% when measured with a
multimeter on the x1 resistance scale.

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Mode 2 Fault Finding
YES
YES
YES
NO
NO
YES
Replace solenoid
Retest operation
NO
Replace element
Retest operation
NO
YES Replace thermistor
Retest operation
NO
YES
Refit the thermistor in the
correct position
Retest operation
NO
Adjust the temperature setting
by following the potentiometer
procedure in this manual.
Retest operation if fault
persists replace the ECB
YES
NO Replace ECB
Retest operation
2.5, 5 & 7.5 litre models
NO
Replace relay
Retest operation
YES
15, 25 & 40 litre models
2
Is voltage present
at the element?
TEST 5 Capacity of Lazer?
Is voltage
present at relay?
TEST 6
Has the
Solenoid closed?
Is the resistance
of the element correct?
TEST 7
2.2
Does the unit
boil continuously?
2.1 3
Does the solenoid close
when upper water level
reached?
Is the resistance of
the thermistor correct?
TEST 8
Is the thermistor fully
inserted into the well?

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Component Tests 5 - 8
Test 5
Test 6
Install RCD and exercise caution when
conducting live tests
Normal voltage at the element is 240v when
measured with a multimeter on the AC voltage
scale
Install RCD and exercise caution when
conducting live tests
Normal voltage to the relay coil is 240v when
measured with a multimeter on the AC voltage
scale.
Test 7
Test 8
Normal resistance of the element and ECO when
measured with a multimeter on the x1 resistance
scale is:
2.4kW - 23.7 ohms +/- 5%
3.6kW - 15.7 ohms +/- 5%
4.6kW - 12.3 ohms +/- 5%
Normal resistance of the water temperature
sensor (Thermistor) is 950 ohms - 1000 ohms
at 20ºC. The Thermistor should be replaced if
the reading is less than 850 ohms or greater
then 1250 ohms. When measured with a
multimeter on the x1K scale a normal reading
will be between .95 and 1.00.

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Mode 3 & 4 Fault Finding
NO
Any time the solenoid is open
for a period exceeding 25
seconds before a shift in
temperature is detected the
unit will enter the over
temperature mode (OTC)
YES
Check for low supply flow due
to water filters etc
Advise customer to draw
smaller quantities of water at
one time
NO
Replace solenoid
Retest operation
YES
YES
Check the water level probe
sensor wires for correct length
NO
Siphoning may be occurring.
Advise user to have a tundish
installed as per the installation
instructions.
Unit may enter over
temperature (OTC) mode
during this condition if the
solenoid opens for periods
exceeding 25 seconds
YES
NO
NO
OTC MODE
Draw a quantity of water from
the unit through the tap
NO
Normal OperationYES
3
Are large quantities of hot
water being discharged
from the vent pipe?
Is the vent pipe
longer than 3 metres?
1
Does the unit discharge
large quantities of hot
water intermittently?
Does the unit maintain
water temperature during
periods of non use?
Did the unit
Refill and heat?
2.2
4
Are large amounts
of hot water being drawn
through the tap?

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LAZER BOILING WATER UNITS AT HIGH ALTITUDES
An increase in altitude will reduce the boiling temperature of water. Therefore it is necessary to
provide an adjustment on the Lazer Control System for installations over 300 metres above sea
level.
All controllers supplied as a component of the finished product are factory adjusted to deliver
water at a temperature of 92ºC.
Why should temperature adjustment be necessary?
Replacement of the Electronic Controller
Replacement of the Thermistor or a Heating Unit and Thermistor.
Altitude compensation
Where is the Adjustment Potentiometer and what does it look like?
Relative to the controller terminals, the Potentiometer (Trim Pot) for temperature adjustment is
located at the right rear of the control box. Access is provided by means of a 10mm diameter hole
in the controller cover (refer to figure below). Some controllers have no covers fitted, so the Trim
Pot is visible on the PCB at the described location.
The Trim Pot can be identified as being a white or blue disc, approximately 6mm in diameter and
having a screw driver slot in its top face.
The dotted lines of the
TRIM POT arc
represent “HOURS”.
Each hour represents
approx 1ºC
How to Adjust the Temperature Setting of the Controller (ECB)
Components adjacent to the trim pot will be live, take care while making
adjustments not to touch other components.
1. Isolate the electrical supply and drain the Lazer Boiling Water Unit to a low level.
2. Using a 3mm wide screw driver, rotate the Trim Pot ANTICLOCKWISE to its MINIMUM
SETTING.
3. Switch the power back ON and allow it to operate automatically for 5 MINUTES (the
element should switch on and the solenoid valve should operate at least once).
4. Using a 3mm wide screw driver, rotate the Trim Pot CLOCKWISE to its MAXIMUM
SETTNG. The unit will now boil and not take water.
5. Allow the unit to boil for approx. 1 minute before rotating the Trim Pot ANTICLOCKWISE
until such time as the solenoid opens, allowing water to flow into the tank.
6. Rotate the Trim Pot ANTICLOCKWISE a further turn (approx. 45 degrees). This will
prevent the unit from boiling should atmospheric pressure decrease.
7. Before re-fitting the jacket cover wait at least one solenoid operation to ensure that the unit
has been correctly adjusted.

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ELECTRICAL IN-SERVICE TESTING
Wear Personal Protective Equipment when conducting step 1 of these
procedures to reduce the risk of electric shock. Refer to Rheem safety
procedure on electrical testing.
1. For 3 –15L models: Isolate power by switching off at power point and unplugging
BWU 3 pin plug from power point.
For 25 & 40L models: Isolate power by turning isolation switch off and then
removing fuse (or switching off circuit breaker). Disconnect Active, Neutral and
Earth wires from BWU terminal block.
Procedure 1: To check insulation resistance of the BWU Neutral Circuit (reading not to
be below 1 mega-ohm).
2. For 3 –15L models: Connect megger leads to the neutral and earth pins on the 3-pin
plug.
For 25 & 40L models: Connect megger leads to the Neutral conductor and the Earth
terminal of the BWU terminal block.
3. Operate insulation resistance tester. A reading above 1 mega ohm should be obtained.
4. If a reading below 1 mega ohm is indicated, all component parts will need to be
individually tested to locate the fault.
Procedure 2: To check insulation resistance of the BWU Active Circuit (reading not to
be below 1 mega-ohm).
5. For 3 –15L models: Connect megger leads to the active and earth pins on the 3-pin plug.
For 25 & 40L models: Connect megger leads to the active conductor and the earth
terminal of the BWU terminal block.
6. Operate insulation resistance tester. A reading above 1 mega ohm should be obtained.
7. If a reading below 1 mega ohm is indicated, all component parts will need to be
individually tested to locate the fault.
Procedure 3: To check “Earth Continuity” of the water heater.
8. Set the multimeter to x1 Ω (ohms) resistance scale.
9. (3 –15L Models) Measure between the earth pin on the 3 pin plug and the water heater
jacket. The reading should be less than 0.5Ω.
(25-40L models) Measure between the earth terminal and the water heater jacket. The
reading should be less than 0.5Ω.
10.If a reading greater than this value is obtained the earthing connection should be checked
for corrosion/tightness and the power lead earth wire tested, if necessary replace the
power lead.

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions
REV AD. Issue 02/01/14
This document is stored and maintained electronically by Service. All printed copies are deemed “uncontrolled”
19
ACCESSING COMPONENTS
Ensure that the unit is unplugged or isolated from the electrical supply.
Removing & Replacing Jacket Lid and Name Plate
(741/751 Series)
Removing the Lid (Figure 1)
1. Remove the four retaining screws.
2. Remove the LID by lifting from the jacket.
Figure 1
Removing the Nameplate (Figure 2)
1. Remove the two retaining screws.
2. Slide the Nameplate forward on the Tap Stem and
rotate through 90 degrees to obtain access to
components.
Note: The Tap does not need to be removed to service
or replace components housed behind the Nameplate.
Figure 2
Removing & Replacing Jacket Front
(761 and 791 Series)
Removing the Jacket Front (Figures 3&4)
1. Remove the two retaining screws. (Figure 3)
2. Remove the spout by pulling down and gently
pushing toward the back.
Figure 3
3. Insert fingertips between the Jacket Front and Jacket
Back in the vicinity of the Jacket Retaining Clips and
gently pull the Jacket Front forward until free of tap.
(Figure 4)
4. Lift the Jacket Front until free of the Retaining Clips.
Warning: The LED Display lead (item 1, figure 4) must
now be disconnected from the ECB. The Jacket Front is
then free to be removed.
Figure 4

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions
REV AD. Issue 02/01/14
This document is stored and maintained electronically by Service. All printed copies are deemed “uncontrolled”
20
COMPONENT REPLACEMENT
Water Temperature Sensor (Thermistor)
Ensure that the unit is unplugged or isolated from the electrical supply.
741/751 Series
1. Remove the nameplate. (Refer to page 19)
2. Disconnect the wiring to the water temperature
sensor.
3. Withdraw the water temperature sensor from the
element.
4. Coat the thermistor with “heat sink compound”
5. Slide the replacement water level sensor into the
element ensuring it seats at the end of the tube.
6. Reconnect the wiring and refit the nameplate.
7. Restore power and test operation of boiling water
unit.
Figure 5
761, 771/781 & 791 series 2.5L –7.5L
1. Remove the jacket front.
2. Disconnect the wiring to the water temperature
sensor.
3. Withdraw the water temperature sensor from the
element.
4. Coat the thermistor with “heat sink compound”
5. Slide the replacement water level sensor into the
element ensuring it seats at the end of the tube.
6. Reconnect the wiring and refit the nameplate.
7. Restore power and test operation of boiling water
unit.
771/781 series 15L –40L
1. Remove the left hand side panel. (Refer to figure 9
page 22)
2. Disconnect the wiring to the water temperature
sensor.
3. Withdraw the water temperature sensor from the
element.
4. Coat the thermistor with “heat sink compound”
5. Slide the replacement water level sensor into the
element ensuring it seats at the end of the tube.
6. Reconnect the wiring and refit the nameplate.
7. Restore power and test operation of boiling water
unit.
Figure 6