Bosch Worcester Greenstar Si Series User manual

UK/IE
USER INSTRUCTIONS
WALL HUNG RSF GAS FIRED CONDENSING COMBINATION BOILER
GREENSTAR Si
6720643356-00.1Wo
FOR CENTRAL HEATING SYSTEMS AND MAINS FED DOMESTIC HOT WATER
6 720 643 356a (2010/10)

2
PREFACE
6 720 643 356a (2010/10)
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 almost 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
6 720 643 356a (2010/10)
CONTENTS
1 Symbols and safety precautions . . . . . . . . . . . . . . . 4
1.1 Explanation of symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 safety precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 General Information . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 Operating the boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1.1 Setting the central heating temperature . . . . . . . . . . . . . 8
3.1.2 Switch off the central heating . . . . . . . . . . . . . . . . . . . . . 8
3.1.3 Boiler frost protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1.4 Setting the hot water temperature . . . . . . . . . . . . . . . . . . 9
3.1.5 Domestic hot water pre-heat . . . . . . . . . . . . . . . . . . . . . . 9
3.1.6 Boiler reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4 System Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1 Sealed heating systems . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2 Using the optional integral filling kit . . . . . . . . . . . . . . . 12
4.3 External filling loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5 Service Clearances . . . . . . . . . . . . . . . . . . . . . . . . . 14
6 Maintaining your Boiler . . . . . . . . . . . . . . . . . . . . . 15
7 Fault Finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8 Fault or Breakdown . . . . . . . . . . . . . . . . . . . . . . . . . 18
9 TIPS ON ENERGY SAVING . . . . . . . . . . . . . . . . . . . 19
10 Environment / disposal . . . . . . . . . . . . . . . . . . . . . 21
11 Your Guarantee . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
12 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4
SYMBOLS AND SAFETY PRECAUTIONS
6 720 643 356a (2010/10)
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 personal
injury.
•CAUTION indicates possible personal injury.
•WARNING indicates possible severe personal 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.
Electrical hazards are identified by a lightning symbol surrounded by a warning triangle.
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)
Tab. 1 Symbols

5
SYMBOLS AND SAFETY PRECAUTIONS
6 720 643 356a (2010/10)
1.2 SAFETY PRECAUTIONS
IF YOU SMELL GAS!
BCall the National Gas Emergency Service on: 0800 111 999
BExtinguish any naked flames
BDo not smoke or strike matches
BDo not turn electrical switches on or off
BOpen doors and windows
BKeep people away from the affected area
BTurn off the gas control valve at the meter
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 warranty.
BDo not store or use any combustible materials (paper, thinners, paints etc.) inside or within the
vicinity of the boiler.
FITTINGS AND MODIFICATIONS:
Only a competent engineer in accordance with the Gas Safety (Installation and Use) Regulations can
remove the outer case and carry out any work.
BDo not remove the outer casing.
Any misuse or unauthorised modifications to the boiler, flue or associated components and system will
invalidate the warranty.
BDo 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.

6
GENERAL INFORMATION
6 720 643 356a (2010/10)
2 GENERAL INFORMATION
SERVICING
BThe boiler must be serviced regularly by a competent, qualified person, such as a Worcester service
engineer or other Gas Safe registered engineer.
BAlways use original spares, to help maintain the economy, 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 warranty 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 “log book” 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 manufacturers
instructions.
The log book provides space for the recording of regular servicing of the boiler/system and this can
become a valuable document when, for example, the householder wishes to sell the property. The log
book will show a potential purchaser that the heating system has received regular professional
attention 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”
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.

7
CONTROLS
6 720 643 356a (2010/10)
3CONTROLS
BTo gain access to the boiler controls push the top centre of the flap and release.
Fig. 1 Control panel fascia
Boiler
Controls
1Central heating temperature control 6 ECO button
2Burner indicator (Green) 7 Reset button
3Service button 8 Hot water temperature control
4Cover or optional Programmer 9 System pressure gauge
5Power ON and fault indicator (Blue)
12345678
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9

8
CONTROLS
6 720 643 356a (2010/10)
3.1 OPERATING THE BOILER
3.1.1 SETTING THE CENTRAL HEATING TEMPERATURE
1. Turn the central heating temperature control knob to the desired level.
Temperatures given in the figure below are approximate.
2. The Burner indicator (green) will illuminate to show that the boiler is running.
Fig. 2 Central heating temperature control
3.1.2 SWITCH OFF THE CENTRAL HEATING
1. Turn the temperature control knob to the snowflake symbol to switch off the central heating.
Fig. 3 Switch off central heating
3.1.3 BOILER FROST PROTECTION
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.
Min
1
2
3
4
5
6
Max
---
---
---
---
---
---
---
---
40 °C
47 °C
53 °C
61 °C
68 °C
74 °C
80 °C
82 °C
2
34
5
6
max
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1.
2.
1
2
34
5
6
max
reset
eco
1
2
34
e
6
maxmin
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1.

9
CONTROLS
6 720 643 356a (2010/10)
3.1.4 SETTING THE HOT WATER TEMPERATURE
1. Turn the hot water temperature control knob to the desired level.
Fig. 4 Hot water temperature
3.1.5 DOMESTIC HOT WATER PRE-HEAT
The hot water heat exchanger is kept “pre-heated” to reduce the time taken to deliver hot water at the
tap. Pre-heat is enabled by default, during the initial boiler start up and the ECO button is not
illuminated.
Eco mode is an energy saving function allowing hot water to be heated only as and when required, by
running a hot tap, this OFF by default.
1. Press and hold the Eco button for at least four seconds to enter the energy saving Eco mode, when
Eco mode is active the Eco button will be illuminated.
Fig. 5 Eco mode
1
2
34
5
6
max
reset
eco
1
2
34
e
6
maxmin
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1.
1
2
34
5
6
max
reset
eco
1
2
34
e
6
maxmin
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1.

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CONTROLS
6 720 643 356a (2010/10)
3.1.6 BOILER RESET
In the event of a fault, the reset button will flash once per second and the blue mains indicator light
will flash.
1. To reset the boiler press the reset button for approximately five seconds.
When the boiler resets the reset button will no longer be illuminated.
2. The mains indicator will no longer be flashing.
Fig. 6 Reset button and mains light
If the fault remains and cannot be cleared by pressing the reset button, contact
Worcester, Bosch Group for assistance.
1
2
34
5
6
max
reset
eco
1
2
34
e
6
maxmin
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1.
2.

11
SYSTEM PRESSURE
6 720 643 356a (2010/10)
4SYSTEMPRESSURE
4.1 SEALED HEATING SYSTEMS
This boiler is fitted to a sealed heating system which is pre-pressurised. Your installer will advise you
of the minimum and maximum pressure indicated on the pressure gauge.
BCheck regularly that the pressure is maintained.
Fig. 7 Optimum pressure when cold (area A)
BContact your installer or maintenance engineer if a permanent significant decrease or increase in
pressure is indicated on the pressure gauge.
The filling method will be one of two types:
•Optional integral filling kit, which is supplied with a white T shaped filling key.
•An external filling loop, fitted valves and flexible hose.
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2
3
1
04
bar
1
A
Min
1 bar
1.5 bar
Max

12
SYSTEM PRESSURE
6 720 643 356a (2010/10)
4.2 USING THE OPTIONAL INTEGRAL FILLING KIT
Locate filling key and follow instructions for re-pressurising.
1. Push the filling key firmly into the body of the filling link, ensuring the arrow on the key shaft lines
up with the open padlock symbol.
2. Turn the filling key to the right, to the stop, so the arrow now lines up with the closed padlock
symbol. This bridges the gap between the two sections of the filling loop.
3. Turn the white knob, to the left of the key, anticlockwise. This will allow water to fill the system.
Fig. 8 Inserting the filling key
4. When the pressure, shown on the pressure gauge, reaches between the 1 and 1.5 bar marks, turn
the white knob clockwise to close the valve.
5. Turn the filling key to the left, to the stop, so that the arrow lines up with open padlock symbol and
pull the key the key straight down to remove.
3.
2.
1.
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4.
5.

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SYSTEM PRESSURE
6 720 643 356a (2010/10)
4.3 EXTERNAL FILLING LOOP
Once the external filling loop has been located, follow the instructions for re-pressurising.
1. Unscrew blanking cap.
2. Attach hose and screw on hand-tight to valve.
3. Turn the handle/screwdriver slot point 90° to open the valves.
4. The handle/screwdriver slot point will be in-line with the valves
Fig. 9 External filling loop
5. When the pressure reaches between the 1 and 1.5 bar marks, turn the handle/screwdriver slot point
back to close it.
6. Remove the hose and replace the blanking cap.
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1. 2. 3. 3.
4.4.

14
SERVICE CLEARANCES
6 720 643 356a (2010/10)
5 SERVICE CLEARANCES
Your installer will have provided adequate space around the boiler for safety and servicing access.
Fig. 10 Service clearances
CAUTION: Restricted space.
The boiler may overheat.
BDo not restrict this space with the addition of cupboards, shelves etc. next to the
boiler.
+ 30 mm
above elbow
5 mm
600 mm
5 mm
200 mm
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15
MAINTAINING YOUR BOILER
6 720 643 356a (2010/10)
6 MAINTAINING YOUR BOILER
Your new gas-fired boiler represents a long term investment in a reliable, high quality product.
In order to realise its maximum working life, and to ensure it continues to operate at peak efficiency
and performance, it is essential that your boiler receives regular servicing and maintenance checks
from a competent person beyond the initial 2 year guarantee period.
If you would like to know more about a Worcester, Bosch Group service contract, please tick the
appropriate box on your warranty registration card.
If your gas-fired boiler should fail to operate correctly or requires servicing please contact Worcester,
Bosch Group Appointments Team (see rear cover for details).
Details of the boiler including the Gas Council number can be found under the controls covers flap on
the boiler.
The Gas Council number is also listed on the front cover of your Installation, Commissioning and
Servicing Instructions.

16
FAULT FINDING
6 720 643 356a (2010/10)
7FAULTFINDING
If a boiler fault occurs, please read the following page thoroughly before contacting Worcester, Bosch
Group.
Problem Cause Remedy
Desired room temperature is
not reached
Thermostatic radiator valve(s)
set too low
BIncrease thermostatic
radiator valve setting(s)
Temperature control for
central heating flow on boiler
set too low
BIncrease central heating
flow temperature control
setting
Air trapped in heating system BBleed radiators and
recharge heating system
Desired room temperature
exceeded by large amount
Radiators are too hot BTurn down thermostatic
radiator valves/room
thermostat
BReduce central heating
temperature by turning
down the Central Heating
control on boiler
Heating stays on for too long Clock is incorrectly set BCheck setting and adjust
No ON/OFF mains indicator Momentary power failure BSwitch off boiler at master
switch, wait a few seconds
then switch on again
Hot water temperature too
low
Temperature set too low BCheck setting and adjust
Water flow at tap too high BReduce flow rate at tap
Hot water temperature too
high
Temperature set too high BCheck setting and adjust
Water flow at tap too low BIncrease flow rate at tap
Tab. 2

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FAULT FINDING
6 720 643 356a (2010/10)
EXTREME COLD WEATHER
In instances where the condensate pipe work is run external or in an unheated area, such as a garage,
it can be at risk of freezing, even if insulated.
A frozen condensate pipe will cause the boiler to shut down.
If the condensate pipe has frozen:
BLocate the blockage.
It is likely that the pipe is frozen at the most exposed point external to the building or where there
is some obstruction to flow. This could be the open end of the pipe, at a bend or elbow, or where
there is a dip in the pipe in which condensate can collect. The location of the blockage should be
identified as closely as possible before taking further action.
BThaw the frozen pipe.
The pipe can be thawed by applying a hot water bottle, a microwaveable heating pack (the sort used
for muscular aches and pains) or a cloth soaked in hot water to the exterior of the pipe, close to
the point of blockage. Hot water can also be poured onto the pipe from a watering can or similar
container.
BOnce the pipe has been thawed the boiler must be reset, press the reset button for five seconds
and wait two to three minutes for the boiler to restart.
BIf the boiler does not restart, contact Worcester’s Technical Support Team (0844 892 3366) for
assistance.
BContact your installer in order to find a permanent solution to the problem.
WARNING: Falling hazard!
Failure to follow this guidance can result in personal injury.
BOnly attempt to thaw a condense pipe that is at ground level, which is easily
accessible.
BNever attempt to thaw a condense pipe which is at height.
CAUTION: Pipe damage
BDO NOT use boiling water to thaw the condensate pipe!

18
FAULT OR BREAKDOWN
6 720 643 356a (2010/10)
8 FAULT OR BREAKDOWN
This boiler is supported in the UK and Eire by Worcester, Bosch Group.
Specialist Service Engineers are available to attend a breakdown occurring on this boiler.
•No charge will be made for parts and/or labour providing:
A boiler fault is found and the appliance has been installed within the past 24 months. Reasonable
evidence of this must be supplied on request. i.e. the Benchmark Checklist.
•A call-out charge will be made where:
–The boiler has been installed for over 24 months.
–Evidence cannot be provided that the first year service inspection has been carried out (i.e. an
entry in the Benchmark Checklist).
–Our Field Service Engineer finds no fault with the boiler.
–The cause of breakdown is misuse or with other parts of your plumbing/heating system, or with
equipment not supplied by Worcester, Bosch Group.
TECHNICAL SUPPORT
In the event of a boiler fault or breakdown please contact Worcester, Bosch Group appointments team
on 0844 892 3000.
Your advisor will arrange for an engineer to call with the minimum of delay; under normal
circumstances this will be from 1 - 3 working days (excluding weekends) for priority breakdown
situations (no hot water and/or heating).
Invoices for attendance and repair work carried out on this boiler by any third party will
not be accepted.
No boiler fault is found on over 30% of all service calls.
In the case of a suspected fault, refer to the fault finding section of this guide.

19
TIPS ON ENERGY SAVING
6 720 643 356a (2010/10)
9 TIPS ON ENERGY SAVING
HEATING ECONOMICALLY
The boiler provides a high level of comfort whilst keeping gas consumption and the environment
effects as low as possible.
The gas supply to the burner is controlled according to the level of demand for heat. The boiler
operates with a low flame if the demand for heat reduces. The technical term for this process is
modulating control.
Modulating control reduces temperature fluctuations and provides an even distribution of heat
throughout the home. This means that the boiler may stay on for relatively long periods of time but will
use less gas than a boiler that continually switches on and off.
CENTRAL HEATING SYSTEMS WITH ROOM THERMOSTAT/THERMOSTATIC RADIATOR VALVES
With modern heating systems set around a 20 °C heat loss, the optimum setting for a condensing boiler
will be approximately between one and two on the central heating temperature control. The system
must be balanced correctly and the radiators may need upgrading. This allows the boiler to condense
as much as possible for the central heating system.
The temperature of each room can be set individually (except primary room with the room thermostat)
using the thermostatic radiator valves.
ROOM THERMOSTATS
Reducing the setting of the room thermostat by 1 °C can reduce fuel consumption by up to 10%.
NEW CONTROL SYSTEMS
Upgrade your heating control system if necessary with the latest equipment available. The minimum
level of control is a programmer, interlocking room thermostat and thermostatic radiator valves.
ROOF INSULATION
Around 30% of the heat loss from a property is through the roof. Replace any old insulation with new
insulation, preferably of around 200 mm thickness or more.
WINDOW FRAMES
Single glazed windows, particularly those with steel frames, can lose a great deal of heat.
Consideration should be given to replacement with PVCu or wooden framed double glazed units.
RADIATORS
If a radiator is sited underneath a window, its performance will be affected if the curtains are allowed
to drape over the radiator. Shelves fitted above or in front of the radiator should also be avoided.
It is advisable to manually adjust all thermostatic radiator valves every 2 - 3 months to prevent them
sticking. Ensure radiator valves are correctly set and not damaged.

20
TIPS ON ENERGY SAVING
6 720 643 356a (2010/10)
DRAUGHTS
Try to ensure that draughts around doors, windows, letterboxes and keyholes etc. are
reduced by using a suitable draught excluder.
CURTAINS
Lined curtains, or heavier full length curtains can provide excellent insulation. However,
always ensure that the curtains do not drape over radiators.
WARNING: AIR VENTS
BDo not block or seal any air vents that are installed to ensure that the central heating
boiler operates safely.