Bosch Worcester Greenstar Si Compact ErP User manual

UK/IE
User instructions
Wall hung RSF gas fired condensing combination boiler
Greenstar Si Compact ErP
6720643358-00.1Wo
For sealed central heating systems and mains fed domestic hot water
6 720 813 279 (2014/09)
If you smell gas:
▶ Well away from the building: call the National Gas Emergency
Service on 0800 111 999.
▶ L.P.G. boilers: Call the supplier’s number on the side of the gas
tank.
These appliances are for use with:
Natural Gas or L.P.G.
(Cat. II 2H 3P type C13, C33 & C53)
Model GC Number
Natural Gas 25Si Compact ErP 47-406-73
30Si Compact ErP 47-406-75
L.P.G. 25Si Compact ErP 47-406-74
30Si Compact ErP 47-406-76

2
Preface
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
Preface
Please read these instructions carefully
These instructions are applicable to the Worcester, Bosch
Group appliance 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 appliance manufactured by Worcester, Bosch
Group. The company prides itself on manufacturing appliances
to the strictest quality control standards throughout every
stage of production.
Worcester, Bosch group has led the field in innovative
appliance design and performance for over 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 is
amongst the top energy rated appliances available.
There is also the reassurance of our parts and labour guarantee
- backed up by Worcester Total Cover, an optional complete
maintenance scheme to keep your appliance operating at peak
condition and efficiency.

3
Contents
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
Contents
1 Key to symbols and safety instructions . . . . . . . . . . . . 4
1.1 Key to symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Safety precautions . . . . . . . . . . . . . . . . . . . . . . . . 4
2 General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 Operating the boiler . . . . . . . . . . . . . . . . . . . . . . 8
3.1.1 Boiler display . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1.2 Setting the boiler flow temperature for the central
heating system . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1.3 Boiler frost protection . . . . . . . . . . . . . . . . . . . . . 9
3.1.4 Turning the central heating off during the summer
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1.5 Setting the flow temperature for domestic hot
water system . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1.6 Domestic hot water preheat (with fascia timer
fitted) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1.7 Domestic hot water preheat (without fascia timer
fitted) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
3.1.8 Domestic hot water eco mode . . . . . . . . . . . . 10
3.1.9 Turn off the Operation/fault diagnostic light
(blue) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
4 System Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1 Sealed heating systems . . . . . . . . . . . . . . . . . . 11
4.2 Locating the integral filling link . . . . . . . . . . . . 11
4.3 Optional integral keyless filling link . . . . . . . . 12
4.4 Optional integral keyed filling link . . . . . . . . . . 13
4.5 External filling loop . . . . . . . . . . . . . . . . . . . . . 14
5 Service Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6 Maintaining your appliance . . . . . . . . . . . . . . . . . . . . 16
7 Fault Finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.1 Boiler alert state . . . . . . . . . . . . . . . . . . . . . . . 18
7.2 Boiler reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.3 Extreme cold weather . . . . . . . . . . . . . . . . . . . 19
8 Fault or Breakdown . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9 Tips on energy saving . . . . . . . . . . . . . . . . . . . . . . . . 21
10 Environment / disposal . . . . . . . . . . . . . . . . . . . . . . . 22
11 Your guarantee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
12 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4
Key to symbols and safety instructions
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
1 Key to symbols and safety instructions
1.1 Key to symbols
Warnings
The following keywords are defined and can be used in this
document:
•NOTICE indicates a situation that could result indamage to
property or equipment.
•CAUTION indicates a situation that could result in minor to
medium injury.
•WARNING indicates a situation that could result in severe
injury or death.
•DANGER indicates a situation that will result in severe
injury or death.
Important information
Additional symbols
Examples of additional symbols used
A numbered step in an action sequence
A sequence of numbered steps or actions carried out in a
specific order to complete a task.
1. First action
2. Second action
3. Third action
etc.
A step in an action sequence
A sequence of defined actions or steps carried out in order to
complete a task.
▶Action
▶Nextaction
▶etc
A reference to a related part in the document or to other
related documents.
To refer the reader to a specific figure/table/section within the
manual.
e.g. figure 1.
A reference number to identify or refer to a part or item.
In a related figure, items or parts identified by a sequential
number.
List entries, first and second levels
• A single component/item
• A component/list, made up of multiple parts/items.
– Sub component or sublist of main component/list.
–etc.
1.2 Safety precautions
If you smell gas:
A gas leak could potentially cause an explosion. If you smell gas,
observe the following rules.
▶ Prevent 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.
▶ Turn off the gas at the meter or regulator.
▶ Open windows and doors.
▶ Warn your neighbours and leave the building.
▶ Prevent anyone from entering the building.
▶ Well away from the building: call the National Gas
Emergency Service on 0800 111 999.
▶ L.P.G. boilers: Call the supplier’s number on the side of the
gas tank.
Appliance operation:
This appliance can be used by children aged from 8 years and
above and persons with reduced physical, sensory or mental
capabilities or lack of experience and knowledge, if they have
been given supervision or instruction concerning the use of the
appliance, in a safe way, and understand the hazards involved.
Children shall not play with the appliance.
Cleaning and user maintenance shall not be made by children
without supervision.
Safety instructions in this document are
framed and identified by a
warning triangle which is printed on a grey
background.
This symbol indicates important information
where there is no risk to people or property.
Symbol Meaning
1. a numbered step in an action sequence
▶ a step in an action sequence
a reference to a related part in the document or to
other related documents
a reference number to identify or refer to a part or
item
•alistentry
– a list entry (second level)
Table 1
1

5
General information
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
Combustible and corrosive materials:
Chemically aggressive substances can corrode the appliance
and invalidate any guarantee.
• Do not store or use any combustible materials (paper,
thinners, paints, propellants, cleaning agents etc.) inside
the cupboard containing the appliance or within the vicinity
of the appliance.
Fittings and modifications:
Only a competent engineer can remove the appliance case and
carry out any work, in accordance with the Gas Safety
(Installation and Use) Regulations.
• Do not remove the appliance case.
Any misuse or unauthorised modifications to the appliance,
flue or associated accessories and heating system will
invalidate the guarantee.
• Do not modify the appliance or flue system in any way.
Worcester, Bosch Group accepts no liability arising from any
such actions. This does not affect your statutory rights.
Cleaning the appliance case:
Use a damp, soft cloth to clean the outer painted metal case of
the appliance, do not use chemicals or abrasive materials.
2 General information
2.1 Energy efficiency
Energy efficiency information is given in the Installation,
Commissioning and Servicing Instructions supplied with the
appliance.
2.2 Servicing
• The appliance 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 appliance 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.
2.3 Benchmark standard
The Benchmark initiative is a
code of practice to encourage
the correct installation,
commissioning and servicing of
domestic central heating
appliances and system
equipment.
A “checklist” is dispatched with every appliance and can be
found towards the back of the Installation, Commissioning and
Servicing Instructions. This is a vital document that needs to be
completed by the installer at the time of installation. It confirms
that the appliance has been installed and commissioned
according to the manufacturer's instructions.
The service record provides space for the recording of regular
servicing of the appliance/heating system and thiscan become
a valuable document when, for example, you wish to sell the
property. The service record 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
2.4 User caution
• It is forbidden for any interference with the appliance other
than those actions allowed in this document.
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.
CAUTION: Incorrect use
▶ Any incorrect use can result in danger to
the householder.

6
Controls
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
3Controls
▶ To gain access to the boiler controls pull the flap down using the curved flap handle.
Fig. 1 Basic boiler controls
* for Worcester service engineer use only
Boiler
Controls
1Service menu/back button 9 Scroll down button
2Service engineer symbol = boiler is set to maximum
or minimum output for service
10 The blue light is ON when the boiler is in an
operational mode.
It will also flash to indicate a fault.
3Eco button
4Reset button 11 Position for optional programmer
5Boiler display 12 Hot water temperature control
6Central heating temperature control 13 Diagnostic port*
7Scroll up button
8OK - Select/confirmation button 14 Central heating system pressure gauge
6720643358-02.1Wo
1 3 65 7 8 9 10 11 12 13 1442

7
Controls
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
Display symbols
SCREEN DISPLAY BRIEF DESCRIPTION EXPLANATION
All possible screen symbols This screen is displayed briefly during boiler start up
and shows all the symbols that could be displayed on
the screen.
Numerical display Displays a temperature setting or boiler status code.
Text display Display PreHeat or Eco, or the Alert code
Hot water Displays this symbol during a DHW demand.
Central Heating Displays this symbol during central heating demand.
Service engineer mode Displays during service when the boiler is set to
maximum or minimum output.
Alert Displays along with the boiler status code and
diagnostic code during a fault condition.
Service mode Displays when a qualified service engineer is in the
service menus.
Burner on The boiler is in operation and the flame is alight.
Centigrade indication Displays next to the temperature reading.
Confirmation This symbol confirms a manual change.
Maintenance codes A code displayed with an H and a number relates to a
maintenance issue. This is not a boiler fault but an
indication that something will need attention
concerning the boiler.
The example shown is H13 Service interval reached,
the boiler requires servicing.
Call your installer or Worcester Bosch Group to
organise a service visit.
Table 2
°C
°
F
°C
°C
°F
H 13

8
Controls
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
3.1 Operating the boiler
3.1.1 Boiler display
This is typical of the display when the boiler is not supplying a central heating or hot water demand.
The display will not be backlit and the internal temperature of the boiler is displayed.
When heat is demanded and the boiler fires up, the flame symbol will be displayed.
3.1.2 Setting the boiler flow temperature for the central heating system
1. Turn the central heating temperature control knob to the desired flow temperature between 30 and 82°C, this will be indicated
on the digital display. This is not the room temperature but the flow temperature through the radiators.
The “e” point provides guidance for the maximum temperature setting for optimum energy efficiency.
2. The radiator symbol will be displayed to confirm that the a central heating setting is being changed.
3. The value is displayed during this process, press to exit or after five seconds of inactivity the boiler display will return to
the default screen.
▶ Comfort levels within rooms should be controlled by your thermostatic radiator valves and/or room thermostat.
max
min
2
3
1
04
bar
1
ok
eco
reset
e
max
min
°C
°F
Eco
°C
°F
Eco
6720813275-01.1Wo
ok
max
min
2
3
1
04
bar
1
ok
eco
reset
e
max
min
°C
°F
Eco
1.
6720643358-03.1Wo
°C
°F
Eco
2.
3.

9
Controls
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
3.1.3 Boiler frost protection
If you are leaving your property unoccupied during cold weather, please leave your programmer on constant and your room
thermostat set to 15°C.
▶ 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 does not rise to 9°C within 30 minutes of the pump operating, the boiler will fire up to provide heat to
bring the temperature up.
▶ If the temperature within the boiler falls below 5°C the boiler will fire immediately, 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.
3.1.4 Turning the central heating off during the summer
▶ Turn your programmer/timer to the off position.
▶ Please refer to the programmer/timer manufacturer's instructions.
3.1.5 Setting the flow temperature for domestic hot water system
1. Turn the hot water temperature control knob to the desired level between 40 and 60°C, this will be shown on the digital display.
The value is displayed during this process, press to exit or after five seconds of inactivity the boiler display will return to the
default screen.
3.1.6 Domestic hot water eco and preheat modes
• Eco mode is an energy saving feature which disables the Preheat function. Eco is enabled by default, during the initial appliance
start up and Eco is displayed.
• Preheat mode, the hot water heat exchanger is kept pre-heated to reduce the time taken to deliver hot water at the tap.
In the Preheat mode, if there has been no demand for hot water for 24 hours the appliance will save energy by suspending Preheat
until there is a demand for hot water. At this time Preheat mode is re-activated. It is advised to use a twin channel programmer to
time the Preheat function and switch it off when it is not needed.
Do not switch the appliance off at the mains fused spur.
max
min
2
3
1
04
bar
1
ok
eco
reset
e
max
min
°C
°F
Eco
°C
°F
1.
6720643358-05.1Wo
ok

10
Controls
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
3.1.7 Domestic hot water preheat mode manual activation (Eco mode off)
Eco mode is enabled by default and the PreHeat can be can be enabled.
1. Press and hold for at least four seconds to enter the PreHeat mode, when preheat mode is active, “PreHeat” will be
displayed.
▶ To exit PreHeat mode and return to PreHeat, press and hold for at least four seconds, PreHeat will be displayed.
3.1.8 Domestic hot water preheat mode timed activation, with fascia timer or external timer connected (eco mode off)
When a twin channel programmer is fitted/connected, the Preheat/Eco option can be selected via the programmer.
• Programmer hot water channel ON periods:
– “PreHeat” mode is active and indicated on the appliance display.
• Programmer hot water channel OFF periods:
– “Eco” mode active and indicated on the appliance display.
3.1.9 Turn off the Operation/fault diagnostic light (blue)
You may choose to deactivate the operation/fault diagnostic light. Please ask your installer to set-up this feature.
The light will still flash to alert you to a possible fault, but will not activate during a heat requirement demand for heating or hot water.
eco
eco
max
min
2
3
1
04
bar
1
ok
eco
reset
e
max
min
°C
°F
Eco
6720813275-02.1Wo
1.
°C
°F
Eco
°C
°F
PreHeat
max
min
2
3
1
04
bar
1
ok
eco
reset
e
max
min
°C
°F
Eco
select select
set ?
advance advance
OK
heating hot water
on
once
timed
off
on
once
timed
off
6720813275-03.1Wo
°C
°F
Eco
°C
°F
PreHeat
ON
OFF

11
System Pressure
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
4SystemPressure
4.1 Sealed heating system
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.
▶ Check regularly that the pressure is maintained.
▶ If the pressure gauge reads less than 1 bar then the system requires re-charging.
▶ Contact 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 three types:
• Optional “Keyless”integral filling link
• Optional “Keyed” integral filling link
• An external filling loop, fitted valves and flexible hose.
4.2 Locating the integral filling link
Removing the bottom panel:
1. Pull the catch down.
2. Slide the panel forward and down to remove
Fig. 2 Bottom panel
Fig. 3 Integral filling link location
6720646608-28.1Wo
2.
1.
67206800521-02.2Wo

12
System Pressure
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
4.3 Optional integral keyless filling link
Locate filling link and follow instructions for re-pressurising.
1. If the needle on the appliance pressure gauge reads less than 1 bar, re-charge the system.
2. Pull the blue lever down to start the filling process.
3. Monitor the pressure gauge on the boiler facia.
Fig. 4 Keyless filling link
4. When the needle reaches between 1 to 1.5 bar on the gauge, release the blue lever to stop the filling process.
If the pressure gauge reads more than 1.5 bar as a result of over filling, bleed one radiator until the pressure gauge
returns to between 1 and 1.5 bar.
67206800521-06.2Wo
Min
1 bar
1.5 bar
Max
1
1.
2.
3.
4.

13
System Pressure
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
4.4 Optional integral keyed filling link
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, ensure the key is locked and that it cannot still turn. The arrow should line 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, this will allow water to fill the system.
4. When the pressure, shown on the boiler fascia pressure gauge, reaches between the 1 and 1.5 bar marks (zone A), turn the
white knob to the right to close the valve. Do not overtighten.
5. Turn the filling key to the left, to the stop,so that the arrow lines up with the open padlock symbol and pull the key straight down
to remove. Please remember to store the key in the bottom panel.
Fig. 5 Keyed filling link
If the pressure gauge reads more than 1.5 bar as a result of over filling, bleed one radiator until the pressure gauge
returns to between 1 and 1.5 bar.
3.
2.
1.
6720643356-10.3Wo
4.
5.
2
3
1
04
bar
1
A
Min
1 bar
1.5 bar
Max

14
System Pressure
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
4.5 External filling loop
Once the external filling loop has been located, follow the instructions for re-pressurising the system.
1. Unscrew blanking cap.
2. Attach the hose to the valves, screw on hand-tight.
3. Turn the handle/screwdriver slot through 90° to open the valves.
4. The handle/screwdriver slot will be in-line with the valves
Fig. 6 External filling loop
5. When the pressure reaches between the 1 and 1.5 bar marks (zone A), turn the handle/screwdriver slot back, through 90°, to
close the valve.
6. The handle/screwdriver slot will be at 90° to the valves
7. Remove the hose and replace the blanking caps.
NOTICE: External filling loops
▶ If the filling loop does not look like the one shown in the figure below or you cannot find your filling loop, contact
your installer.
▶ To comply with Water Authority regulations you must disconnect the external filling loop after re-
pressurisation.
If the pressure gauge reads more than 1.5 bar as a result of over filling, bleed one radiator until the pressure gauge
returns to between 1 and 1.5 bar.
2
3
1
04
bar
1
A
Min
1 bar
1.5 bar
Max
6720806947-01.1Wo
1. 2.
7.
4. 4.
3.
3.
6. 6.
5.
5.

15
Service clearances
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
5 Service clearances
Your installer will have provided adequate space around the boiler for safety and servicing access.
Fig. 7 Service clearances
[*] Minimum clearances to removable door
[**] Minimum clearances required for servicing
[***] Height for either 60/100 flue or 80/125 flue
CAUTION: Restricted space.
The boiler may overheat.
▶ Do not restrict this space with the addition of cupboards, shelves etc. next to the boiler.
NOTICE: Combustible and corrosive materials:
Chemically aggressive substances can corrode the appliance and invalidate any guarantee.
▶ Do not store or use any combustible materials (paper, thinners, paints, propellants, cleaning agents etc.)
inside the cupboard containing the appliance or within the vicinity of the appliance.
1060/1100mm***
880mm
300mm
400mm
170/210mm***
600mm**
5mm
5mm
200mm
20mm*
6720646608-122.1Wo

16
Maintaining your appliance
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
6 Maintaining your appliance
Your new gas-fired appliance represents a long term investment in a reliable, high quality product.
Wipe the appliance casing with a soft clean cloth. Please do not use chemical cleaning products which may damage the paint finish.
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 appliance receives regular servicing and maintenance checks from a competent person beyond the initial guarantee
period.
If your Greenstar gas-fired appliance should fail to operate correctly or requires servicing, please contact the Worcester, Bosch
Group Appointments Team (see rear cover for details).
Details of the appliance including the Gas Council number can be found on the front cover of these User Instructions and on the
appliance identification label on the appliance facia.
The Gas Council number is also listed on the front cover of your Installation, Commissioning and Servicing Instructions.

17
Fault finding
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
7Faultfinding
In the event that the appliance stops functioning or does not perform as expected, please see table below These problems are some
of the most common causes. Should the problem persist or if other fault codes are displayed, then it will be necessary to contact
Worcester, Bosch Group.
This table gives information on basic operating system problems.
Problem Cause Remedy
EA fault code flashing on
display
No gas supply/low gas supply pressure ▶ Contact your gas supplier.
Condensate outlet blocked ▶ If it is safe to do so, check your condensate pipe
outlet for blockages, such as ice or foreign objects.
Flue blocked ▶ If it is safe to do so, check your flue outlet for damage
or blockages.
Desired room
temperature is not
reached
Thermostatic radiator valve(s) set too low ▶ Increase thermostatic radiator valve setting(s).
Temperature control for central heating
flow on appliance set too low
▶ Increase central heating flow temperature control
setting
Low temperature setting on the room
thermostat
▶ Increase setting on the room thermostat.
Air trapped in heating system ▶ Bleed radiators and re-pressurise the heating system
Low system water pressure ▶ Re-pressurise the system, refer to page 11
Desired room
temperature too high
Thermostatic radiator valves are set to high ▶ Turn down thermostatic radiator valves.
Room thermostat is set too high ▶Turndownroomthermostat.
Radiators are too hot Temperature control on appliance set too
high
▶ Reduce central heating temperature by turning down
the Central Heating control on appliance.
Note: This could prevent your property reaching the
desired temperature during cold weather periods.
Heating stays on for too
long
Clock is incorrectly set ▶ Check clock setting and adjust
No blue Operation/Fault
Indicator demand
Momentary power failure ▶ Disconnect boiler supply, wait a few seconds then
reconnect.
Heat requirement demand operation on
light has been deactivated
▶ Ask your installer to reset the blue light
Hot water temperature
too low
Temperature set too low on boiler controls ▶ Check setting and adjust
Water flow at tap too high ▶ Reduce flow rate at tap
Air trapped in heating system ▶ Bleed radiators and re-pressurise the heating system
Low system water pressure ▶ Re-pressurise the system, refer to page 11
Hot water temperature
too high
Temperature set too high on boiler controls ▶ Check setting and adjust
Water flow at tap too low ▶ Increase flow rate at tap
Table 3 Fault finding

18
Fault finding
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
7.1 Boiler alert state
In the event of an alert, a fault code and an alert symbol will be displayed on the boiler display, and the blue operation/fault
light will flash, e.g. EA, reset your boiler.
7.2 Boiler reset
1. To reset the boiler, press .
2. “Reset” and are briefly displayed.
▶ If the reset was successful the boiler will return to normal operation.
▶ If the reset was not successful then the alert code will be displayed again, and the blue operation/fault light will continue to flash.
Due to the internal safety systems of your Greenstar CDi CompactErP boiler, some codes cannot be cleared by a simple reset. Please
contact Worcester, Bosch Group for further assistance.
When calling Worcester, Bosch Group about a fault, it will be useful to quote the alert code and three digit number under the alert
code, e.g. EA and 227. If there is a fault that cannot be reset by you, the user, then a service engineer visit will be necessary.
max
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04
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227
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227
6720643358-14.1Wo
reset
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6720643358-09.2Wo
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Reset
1.
2.

19
Fault finding
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
7.3 Extreme cold weather
In certain instances where the condensate pipe work is run externally or in an unheated area, such as a garage, the condensate pipe
work can be at risk of freezing, even if well insulated.
A frozen/blocked condensate pipe will cause the boiler to shut down. Worcester, Bosch Group have available on our website helpful
videos in the Customer service section.
If the condensate pipe has frozen:
▶ Locate the blockage.
It is likely that the pipe is frozen at the most exposed point outside the building or where there is an obstruction to flow.
This could be the open end of the pipe, at a bend or elbow, or where there is a sag in the pipe in which condensate can collect.
The location of the blockage should be identified as closely as possible before taking further action.
▶Thawthefrozenpipe.
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, but not boiling, can also be poured onto the pipe from a watering can or similar container. Care must be taken at
pedestrian areas where this water may freeze and create a slip hazard.
▶ Worcester, Bosch Group have available on our website helpful videos in the Customer service section to aid in thawing a frozen
pipe.
▶ Once 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.
▶ If the boiler does not restart, contact Worcester, Bosch Group Appointments Team on: 0330 123 9339.
▶ Contact your installer in order to find a permanent solution to the problem.
WARNING: Falling hazard!
Failure to follow this guidance may result in personal injury.
▶ Only attempt to thaw a condense pipe that is at ground level and easily accessible.
▶ Never attempt to thaw a condense pipe that is at height.
CAUTION: Pipe damage
▶DO NOT use boiling water to thaw the condensate pipe!

20
Fault or breakdown
Greenstar Si Compact ErP - 6 720 813 279 (2014/09)
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 boiler is within the guarantee period. Reasonable evidence of this must be supplied on request.
i.e. the Benchmark Checklist.
• A call-out charge will be made where:
– The boiler is outside the guarantee period.
– 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 0330 123 9339.
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 and bank holidays) 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.