Bosch Worcester Greenstar 24 User manual

UK/IE
USER INSTRUCTIONS
WALL HUNG RSF GAS FIRED CONDENSING COMBINATION BOILER
GREENSTAR 24/28
6720801019-00.1Wo
FOR SEALED CENTRAL HEATING SYSTEMS AND MAINS FED
DOMESTIC HOT WATER
6 720 801 019 (2012/05)

2
preface
6 720 801 019 (2012/05)
PREFACE
PLEASE READ THESE INSTRUCTIONS CAREFULLY
These instructions are applicable to the Worcester, Bosch Group
boiler model stated on the front cover only.
These instructions apply in the UK/IE only and must be followed
except for any statutory obligation.
After installation please leave this User instruction Manual,
Installation, Commissioning and Servicing Instructions and
completed Benchmark Checklist with the user.
DEDICATED TO HEATING COMFORT
Thank you for purchasing a Greenstar gas-fired condensing
combination boiler manufactured by Worcester, Bosch Group.
The company prides itself on manufacturing boilers to the
strictest quality control standards throughout every stage of
production.
Worcester, Bosch group has led the field in innovative boiler
design and performance for 50 years. This heritage means all our
products are of exceptional quality and proven reliability.
The Greenstar range in particular is extremely energy efficient,
offering you economical running costs and value for money. It sits
in SEDBUK Band A, and is therefore amongst the top energy rated
boilers available.
There is also the reassurance of our no-nonsense 2 years parts and
labour guarantee - backed up by Worcester Total Cover, an
optional complete maintenance scheme to keep your boiler
operating at peak condition and efficiency.

3
Contents
6 720 801 019 (2012/05)
CONTENTS
1 Symbols and safety precautions 5
1.1 Explanation of symbols 5
1.2 Safety precautions 6
2 General information 8
3 Opening the control panel cover 10
4 Overview of controls 11
5Operation 12
5.1 Switching the appliance on/off 12
5.2 Switching on the central heating 14
5.3 System controls 15
5.4 Setting hot water temperature 16
5.5 Frost protection 17
5.6 Button lock 18
5.7 Boiler reset 19
5.8 Display codes 20
5.9 Extreme cold weather 21

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Contents
6 720 801 019 (2012/05)
6SystemPressure 23
6.1 Sealed heating systems 23
6.2 External filling loop 24
7 Fault or Breakdown 26
8 Environment / disposal 27
9 Tips on energy saving 28
10 Your guarantee 30
11 Glossary 32
12 General Information 34
13 Quick reference guide 35

5
Symbols and safety precautions
6 720 801 019 (2012/05)
1 Symbols and safety precautions
1.1 EXPLANATION OF SYMBOLS
WARNING SYMBOLS
Signal words indicate the seriousness of the hazard in terms of the
consequences of not following the safety instructions.
•NOTICE indicates possible damage to property or equipment,
but where there is no risk of injury.
•CAUTION indicates possible injury.
•WARNING indicates possible severe injury.
•DANGER indicates possible risk to life.
IMPORTANT INFORMATION
ADDITIONAL SYMBOLS
Safety instructions in this document are framed
and identified by a warning triangle which is
printed on a grey background.
Notes contain important information in cases where
there is no risk of personal injury or material losses
and are identified by the symbol shown on the left.
They are bordered by horizontal lines above and
below the text.
Symbol Meaning
Ba step in an action sequence
Æa reference to a related part in the document or
to other related documents
•a list entry
–a list entry (second level)

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Symbols and safety precautions
6 720 801 019 (2012/05)
1.2 SAFETY PRECAUTIONS
IF YOU SMELL GAS!
A gas leak could potentially cause an explosion.
If you smell gas, observe the following rules.
BPrevent flames or sparks:
–Do not smoke, use a lighter or strike matches.
–Do not operate any electrical switches or unplug any
equipment.
–Do not use the telephone or ring doorbells.
BTurn off the gas at the meter.
BOpen windows and doors.
BLeave the building and warn your neighbours.
BPrevent anyone from entering the building.
BWell away from the building: call the National Gas Emergency
Service on 0800 111 999.
BOILER OPERATION:
This boiler must only be operated by a responsible adult who has
been instructed in, understands and is aware of the boiler's
operating conditions and effects.
COMBUSTIBLE AND CORROSIVE MATERIALS:
Chemically aggressive substances can corrode the boiler and
invalidate any guarantee.
•Do not store or use any combustible materials (paper,
thinners, paints, propellants, cleaning agents etc.) inside or
within the vicinity of the appliance.
FITTINGS AND MODIFICATIONS:
Only a competent engineer can remove the boiler case and carry
out any work, in accordance with the Gas Safety (Installation and
Use) Regulations.

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Symbols and safety precautions
6 720 801 019 (2012/05)
•Do not remove the boiler case.
Any misuse or unauthorised modifications to the boiler, flue or
associated accessories and heating system will invalidate the
guarantee.
•Do not modify the boiler or flue system in any way.
Worcester, Bosch Group accepts no liability arising from any such
actions. This does not affect your statutory rights.

8
General information
6 720 801 019 (2012/05)
2 GENERAL INFORMATION
SERVICING
•The boiler must be serviced regularly by a competent, qualified
person, such as a Worcester service engineer or other Gas Safe
registered engineer.
•Always use original spares, to help maintain the efficiency,
safety and reliability of the boiler and have the Service Record
completed in the Benchmark Checklist.
The completed Benchmark Checklist will be required in the event
of any guarantee work and may be required by the local Building
Control Inspector.
BENCHMARK STANDARD
The Benchmark initiative is a code of
practice to encourage the correct
installation, commissioning and servicing
of domestic central heating boilers and
system equipment.
A “checklist” is dispatched with every boiler. This is a vital
document that needs to be completed by the installer at the time
of installation. It confirms that the boiler has been installed and
commissioned according to the manufacturer's instructions.
Ensure that the service engineer completes the
Service Record in the Benchmark Checklist after
each service. The Benchmark Checklist and service
interval record can be found at the rear of the
Installation, Commissioning and Servicing
Instructions.

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General information
6 720 801 019 (2012/05)
The log book provides space for the recording of regular servicing
of the boiler/heating system and this can become a valuable
document when, for example, you wish to sell the property. The
log book will show a potential purchaser that the heating system
has received regular professional maintenance and servicing
during its lifetime.
The Benchmark initiative aims to:
•Raise standards among professional installers
•Build and maintain high safety standards in the industry
•Improve customer satisfaction levels
•Make a contribution to the nation's commitment to climate
change

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Opening the control panel cover
6 720 801 019 (2012/05)
3 OPENING THE CONTROL
PANEL COVER
BTo unlatch the flap, push and release at the point indicated.
BTo close and secure the flap, swing up and push in once to
latch.
6 720 612 660-01.2R

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Overview of controls
6 720 801 019 (2012/05)
4 OVERVIEW OF CONTROLS
Fig. 1 Basic boiler controls
1Service engineer symbol = boiler is set to maximum or
minimum output for service
2Service button for heating engineers
3Indicator for burner operation
4Boiler ON/OFF - does not electrically isolate the boiler
5Button lock
6Eco button
7Reset button
8Display
9Hot Water temperature control
10 Pressure gauge
11 Position for optional programmer
12 Central Heating temperature control
13 Indicator for burner operation (ON)/faults (flashing)
6720801019-01.2Wo
1 2 4 5 6 7 8 103
11 12 13
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Operation
6 720 801 019 (2012/05)
5OPERATION
5.1 SWITCHING THE APPLIANCE ON/OFF
SWITCHING ON FOR THE FIRST TIME
BSwitch appliance on at the main switch.
The display indicates the current heating water flow
temperature.
The indicator for burner operation/faults is permanently on, as
long as the burner is operational.
•Please do not turn your boiler OFF. If you switch your boiler off
your frost protection mode will be deactivated.
•Switching the boiler OFF does not electrically isolate the
appliance. Your installer must isolate the mains electricity
before starting work and observe all relevant safety
precautions.
•In the event of an electrical power interruption when the boiler
re-starts it will enter a start-up mode for approximately 15
minutes duration.
max
1
2
34
5
6
6 720 613 896-05.1O

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Operation
6 720 801 019 (2012/05)
The trap filling function ensures that the condensate trap is filled
after the appliance is first installed or if it has not been used for a
long period. For that reason, the appliance is held at minimum
heat output for 15 minutes.
When the flow temperature alternates with the
symbol on the display, the trap filling function
is active.

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Operation
6 720 801 019 (2012/05)
5.2 SWITCHING ON THE CENTRAL HEATING
The maximum flow temperature can be set to between 35°C and
approx. 90°C.
BTurn CH flow temperature control to adjust the max. CH
flow temperature according to the central heating system:
–Underfloor heating: e.g. position 3(approx. 50°C)
–Low-temperature heating system: position 6
(approx. 75°C)
–Heating system for flow temperatures up to 88°C:
max position
When the burner is alight, the green indicator lights up.
With underfloor heating systems, take care to
observe the maximum permissible CH flow
temperatures.
Position CH flow temperature
1 Approx. 35 °C
2Approx.43°C
3Approx.50°C
4Approx.60°C
5Approx.67°C
6 Approx. 75 °C
max Approx. 90 °C
eco
reset
6 720 615 065-12.1O
max
1
2
34
5
6
max
1
2
34
e
6
min

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Operation
6 720 801 019 (2012/05)
5.3 SYSTEM CONTROLS
These Operating Instructions apply only to the boiler.
Depending on the room thermostat and optional programmer
used, some functions may be controlled differently.
Therefore, please read the operating instructions
for the heating controller used.
Follow the operating instructions for the heating
controller used. Those instructions will tell you
Bhow to set the operating mode and the heating
curve for weather-dependent controllers,
Bhow to adjust the room temperature,
Bhow to heat economically and save energy.
912
h
15
18
21
24
h
3
6
6 720 612 660-07.2O

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Operation
6 720 801 019 (2012/05)
5.4 SETTING HOT WATER TEMPERATURE
BSet the hot water temperature on the hot water temperature
control .
The set hot water temperature is shown flashing on the display
for 30 seconds.
ECO BUTTON
Pressing and holding the Eco button until it lights up switches
between Comfort mode and Economy mode.
COMFORT MODE, ECO BUTTON IS NOT LIT (DEFAULT SETTING)
The appliance is held constantly at the set temperature. This
means that hot water is available almost instantaneously at the
tap.
Consequently the appliance will switch on at intervals, even if no
hot water is being drawn.
Hot water temp. control Hot water temperature
min to 1 Approx. 40 °C
eApprox.50°C
6 to max Approx. 60 °C
6 720 614 156-10.1O
max
1
2
34
5
6
reset
eco
max
1
2
34
e
6

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Operation
6 720 801 019 (2012/05)
ECONOMY MODE, ECO BUTTON LIT
•The water is not heated up until a hot water tap is turned on.
•Signalling demand.
Briefly turning a hot water tap on and then off signals demand
so that the water is then heated up to the set temperature.
5.5 FROST PROTECTION
Frost Protection is active as long as there is power to the boiler.
If the temperature within the boiler falls below 8°C the pump will
run to circulate water and prevent the system freezing.
If the temperature within the boiler falls below 5°C the boiler will
fire periodically, bringing the boiler temperature up to 12°C to
avoid the possibility of the system freezing.
This process will be repeated until such time that the boiler
temperature does not drop below 5°C.
Signalling demand enables maximum gas and water
economy.
eco
reset
max
1
2
3
5
6
max
1
2
34e
6
min

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Operation
6 720 801 019 (2012/05)
5.6 BUTTON LOCK
The button lock affects the CH flow temperature control, the hot
water temperature control and all buttons except the main switch
and the service engineer mode button.
To switch on the button lock:
BPress and hold the button until the display shows .
To switch off the button lock:
BPress and hold the button until the display shows only the CH
flow temperature.
max
1
2
34
5
6
max
1
2
34e
6
eco
reset
min

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Operation
6 720 801 019 (2012/05)
5.7 BOILER RESET
In the unlikely event of a fault occurring while the appliance is in
operation:
The reset button will flash once per second and the mains
indicator (blue light) also flashes. The display will show a fault
code.
To reset the boiler, press the reset button until is displayed.
The reset button will no longer be illuminated and the blue light
will stop flashing.
If the reset was successful the boiler will return to normal
operation, depending on programmer and room thermostat
settings.
If the reset was not successful then the blue light will continue to
flash and a fault code will be displayed again.
Info symbol: If the fault remains and cannot be cleared by pressed
the reset button, or if the fault persists please contact Worcester,
Bosch Group for assistance on 0844 892 3000.
In the event of a fault, the reset button will flash once per second
and the blue mains indicator light will flash.

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Operation
6 720 801 019 (2012/05)
5.8 DISPLAY CODES
Display
code Description
Inspection due
Button lock active
Trap filling function active
Air purge function active
Excessively rapid increase in CH flow
temperature (temp. gradient monitoring).
Heating mode is disabled for two minutes.
Not applicable in the UK.
Not applicable in the UK