Rheem 441 Series, 761 Series, 771 Series, 791 Series, 451 Series Service Instructions Manual
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This document is stored and maintained electronically by Service. All printed copies are deemed “uncontrolled”
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
REV AD. Issue 02/01/14
This document is stored and maintained electronically by Service. All printed copies are deemed “uncontrolled”
2
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
REV AD. Issue 02/01/14
This document is stored and maintained electronically by Service. All printed copies are deemed “uncontrolled”
3
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
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”
4
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
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”
5
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.
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”
6
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.
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”
7
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.
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”
8
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 AIRBREAK 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.
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”
9
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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