Bosch WORCESTER Greenstar CDi Classic Series Manual

1
Technical and Specification Information Greenstar CDi Classic Series
Greenstar CDi Compact Series
Greenstar Si Compact Series
Greenstar i Junior Series
Greenstar combi gas-fired condensing
wall mounted boiler range
NEW
Greenstar
Combi range

2
Worcester and you. Making a dif
f
As part of the Bosch Group, Worcester
products are designed and manufactured to
provide customers with the highest levels of
quality and reliability which are synonymous
with the Bosch name throughout the world.
As part of Europe’s largest supplier of
heating products, Worcester, Bosch Group
has the UK-based resources and support
capability to offer you the value-added
solutions you deserve. Worcester employs
a nationwide network of Service Engineers
and technically trained Field Sales Managers
supported by an experienced technical
services team which is able to provide
comprehensive support and advice
from designing system layouts through
to installation.
Worcester is dedicated to providing energy
efficient gas- and oil-fired condensing
boilers, as well as an extensive range of
renewable technologies. All of our products
have been developed and introduced with
the aim of helping the UK to achieve the
Government’s efficiency targets.
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3
f
erence.
“At Worcester we recognise the vital role you
play in the specification and installation of
energy efficient appliances in homes across
the UK. We will continue to invest in our
products, people, facilities and added value
services to ensure you have all you require in
order to deliver only the best solutions to your
customers’ requirements.”
Carl Arntzen,
Managing Director,
Bosch Thermotechnology Ltd.
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Contents Page
The Greenstar combi condensing boiler range 4 - 5
Key features of the range 6 - 7
Greenstar CDi Classic features and benefits 8 - 9
Inside story – Greenstar CDi Classic 10 - 11
Greenstar CDi Compact features and benefits 12 - 13
Inside story – Greenstar CDi Compact 14 - 15
Greenstar Si Compact features and benefits 16 - 17
Inside story – Greenstar Si Compact 18 - 19
Greenstar i Junior features and benefits 20 - 21
Inside story – Greenstar i Junior 22 - 23
Optional plug-in controls 24 - 25
Site preparations and guidance 26 - 31
Greenstar combi installation requirements 32 - 34
The Worcester Greenstar System Filter 35
The Worcester Keyless Filling Link 36 - 37
Condensate pipework 38 - 39
The Worcester CondenseSure siphon 40 - 41
Horizontal and vertical flue terminal positioning 42 - 43
Horizontal fluing options 44 - 47
Vertical fluing options 48 - 50
Plume management positioning and system options 51 - 54
Accessories 55 - 59
Worcester training 60 - 62
After-sales 63
The reception and main entrance
at our Worcester headquarters

4
The Greenstar combi range is part of a market-leading
range of energy-saving gas-fired boilers. Renowned for
their energy efficiency, reliability, ease of installation and
servicing, more than 2 million Greenstar combi boilers have
been installed in homes across the UK.
As part of our commitment to offer installers high quality
products and innovative heating solutions, Worcester has
improved its entire combi range.
Greenstar Si Compact
Greenstar CDi Classic
The Greenstar combi gas-fired wall

5
Now part of the range are the all-new, revolutionary
Greenstar CDi Compact and Si Compact models, which
have an innovative WB7 heat exchanger designed to
combine both compact dimensions with a high efficiency.
Also, the Greenstar CDi Classic has recently undergone a
number of enhancements including increased domestic
hot water performance, a new magnetic flap and reduced
standby electrical consumption.
For lower hot water output applications, the Greenstar
i Junior range has also been improved with the addition of
a DHW control added to the fascia, along with a series of
other features.
Greenstar CDi Compact
Greenstar i Junior
mounted condensing boiler range

6
Key features of the range
Winner of Which? Best Buy awards
in 2011, 2012 and 2013
For three consecutive years, in a survey of
Which? members, the Worcester Greenstar
gas-fired condensing boiler range has been
presented with Best Buy awards.* In the
latest survey, no other manufacturer scored
higher for reliability and customer satisfaction.
Highly efficient, highly cost-effective
All Worcester Greenstar condensing combi boilers
have an annual A rated efficiency (SEDBUK 2005
value) of over 90%, efficiently producing heating
and hot water for the home. Non-condensing boilers
achieve around 78% efficiency.
Low NOx options
Worcester’s commitment to reduce emissions from
gas-fired condensing boilers sees all Greenstar
combi boilers achieve NOx values <40mg/kWh.
This enables the appliances to achieve 3 credits
under the Code for Sustainable Homes. The i Junior
requires a low NOx code plug which is available
as an optional accessory. All other boilers are low
NOx as standard.
Hot water mode
Whenever a hot water tap is turned on, the
incoming mains water will activate a flow turbine
which, via the electronic control system, ignites
the pre-mix burner. Boiler output is automatically
boosted to maximum in order to heat the incoming
cold water as it passes through the heat exchanger.
Electronic controls modulate the boiler output to
ensure an accurate hot water temperature.
Keep hot facility
All Greenstar combi models have an in-built
‘keep hot’ facility which will keep the primary water
within the heat exchanger hot – approximately
2.5 litres volume. This will ensure that hot water is
delivered almost instantly to the opened outlet.
ECO mode
With the ECO mode button activated, the ‘keep hot’
facility is de-energised and the hot water will be
heated from cold. A slight delay should be expected
before the hot water is at full temperature when in
ECO mode. By selecting ECO mode, less gas will be
used as energy is used only on demand.
Central heating mode
On a central heating demand, the boiler will initially
fire at minimum output before modulating upwards
to meet the system’s actual requirement. Electronic
controls within the boiler continually monitor the
heating flow and return temperature and increase
or decrease the output on demand.
Fluing options
The Greenstar combi range has a full range of
Condensfit II™ flue options in both 60/100mm
and 80/125mm diameters and include a plume
deflector as standard. This versatile flue system
can be run horizontally or vertically.
The Greenstar Si Compact
has the same fascia with an
intuitive in-built display as the
Greenstar CDi Compact

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The Greenstar combi range at a glance
Boiler 29CDi
Classic
34CDi
Classic
38CDi
Classic
42CDi
Classic
28CDi
Compact
32CDi
Compact
36CDi
Compact
25Si
Compact
30Si
Compact
24i
Junior
28i
Junior
Part No. NG
LPG
7 738 100 216 7 738 100 218 7 738 100 222 7 713 331 019 7 716 130 234 7 716 130 235 7 716 130 236 7 716 130 230 7 716 130 232 7 716 130 220 7 716 130 222
7 738 100 217 7 738 100 219 7 738 100 223 7 713 331 020 7 716 130 237 7 716 130 238 7 716 130 239 7 716 130 231 7 716 130 233 7 716 130 221 7 716 130 223
Output kW to DHW
Min
Max
7.7kW 7.7kW 9.4kW 9.4kW 7.03kW 7.03kW 7.03kW 7.03kW 7.03kW 7.2kW 7.2kW
30.9kW 35kW 40kW 42kW 28kW 32kW 36kW 25kW 30kW 24kW 28kW
Flow rate at 35ºC ∆T
(± 15%)
12.3l/min 14.3l/min 16.4l/min 17.2l/min 11.4l/min 13.1l/min 14.7l/min 10.2l/min 12.3l/min 9.8l/min 11.4l/min
Flow rate at 40ºC ∆T
(± 15%)
11l/min 12l/min 14l/min 15l/min 10l/min 11.5l/min 12.9l/min 8.9l/min 10.7l/min 8.6l/min 10l/min
Output kW to Min
central heating (CH) Max
7.7kW 7.7kW 9.4kW 9.4kW 7.03kW 7.03kW 7.03kW 7.03kW 7.03kW 7.2kW 7.2kW
30kW 30kW 30kW 30kW 24kW 24kW 24kW 24kW 24kW 24kW 24kW
Maximum output kW
to central heating (CH)
with low NOx code plug
–––––––––13kW 13kW
CH temperature control 99999999999
DHW temperature
control 99999999999
Modulating control 99999999999
Electronic ignition 99999999999
In-built filling link 9999999
(optional) (optional) (optional) (optional)
Condensing in DHW 999999999
––
*
The Greenstar condensing combi range –
features and benefits at a glance
Energy-saving & environmental
•SEDBUK A rating of 90.1%
and above (2005 value)
•Simple and intelligent control
options are available to optimise
boiler efficiency
•Low electrical consumption in
standby mode
•Aluminium-silicon heat exchangers
deliver high efficiency and reliability
•Greenstar CDi Classic, CDi Compact
and Si Compact condense in
DHW mode
•Modulating pump which uses less
electricity than a fixed speed pump –
Greenstar CDi Classic and
CDi Compact only
•Anti-cycle control.
Time & labour-saving installation
•Wall frame allows space for pipes
behind the boiler as standard
•Vertical pre-piping assembly
available as an accessory
•Full range of Condensfit II™
flue options
•Multi-directional fluing means
boiler can be sited in a wider
variety of places
•The boiler comes pre-wired and
pre-plumbed
•There is no need to install a hot
water cylinder
•There is no need to install a
storage tank in the roof space
•There is less pipework in the
heating system.
End user comfort and convenience
•10 year guarantee on Worcester
primary heat exchanger†
•Boiler protection plans available
for both new and out-of-guarantee
Worcester Greenstar boilers
•Bosch renowned quality
and reliability
•Built-in boiler frost protection
•Small dimensions –
Greenstar CDi Compact, Si Compact
and i Junior models
•ECO mode for energy-saving fuel
consumption
•Controls behind flap – aesthetically
pleasing and minimises the risk of
tampering with controls.
*Source: Which? 2013 survey published in Sept 2013. †Subject to terms and conditions.

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Greenstar CDi Classic
Features and benefits
The top-of-the-range, award-winning Greenstar CDi Classic is a high
performance boiler that is suitable for small, medium and large-sized
properties with one or two bathrooms. It has set the benchmark within
the industry for efficiency, reliability and ease of installation, while
achieving a market-leading output of up to 42kW.
The Greenstar CDi Classic offers the opportunity to range-rate the central
heating output to perfectly match the properties’ requirements which
reduces cycling and improves efficiency further.
As well as being the flagship boiler in our Greenstar combi range, the
upgraded CDi Classic now benefits from a number of new improvements
including higher DHW flow rates of 12.3, 14.3 and 16.4 to complement
the already class-leading 17.2 l/min performance.
The improvements to the control box now includes lead-free components
for environmental benefits, a clearer display for temperatures and
commissioning settings, and a new short-circuit-proof PCB design that
removes the need for fuses on the low voltage circuits. The control box
casing is more water-resistant due to the removal of the transformer, while
the lift weight of the appliance has also been reduced to 47.5kg.
The Greenstar CDi Classic achieves 3 credit points within the Code for
Sustainable Homes and has an A rated annual efficiency of up to 90.2%
(SEDBUK 2005 value).
Greenstar CDi Classic is
available with DHW flow rates
of 12.3, 14.3, 16.4 and
17.2 l/min
Installation benefits
•Standard wall frame allows space for
pipes behind the boiler
•Can be serviced entirely from the
front with easy access to parts
and components
•All models available as natural gas and
LPG for a range of properties
•Split wall-mounting jig provided as
standard for pre-plumbing of all
7 connections – gas, water, PRV &
condensate connections before the
boiler is on the wall
•Full range of Condensfit II™ horizontal and
vertical flue options with optional plume
management kit available
•Multi-directional fluing means boiler can
be sited in a wider variety of places.
Environmental benefits
•SEDBUK A rating of up to 90.2%
(2005 value)
•WB5 heat exchanger delivers high
efficiency and reliability
•Low electrical consumption when in
standby mode
•NOx emissions of 35mg/kWh –
achieves 3 credits under the Code
for Sustainable Homes
•All boilers and components are 100%
recyclable, achieving Worcester’s zero
waste to landfill objective.

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*Terms and conditions apply.
WB5 heat exchanger
The Worcester WB5 heat exchanger
has been designed to optimise clean
burning combustion over an extra-
large surface area. Each heat
exchanger is factory-set and 100%
tested so, as long as the gas inlet
pressure is correct, commissioning
is straightforward. The heat
exchanger requires minimal
servicing which means fewer spare
parts during its lifetime. The heat
exchanger can be cleaned in situ via
an inspection hatch, again saving
time during service.
2 million installed and still
going strong
With more than 2 million Greenstar
combi boilers installed in the
UK, the ever popular Worcester
Greenstar CDi Classic, with its
advanced features and future-proof
technology, still sets the standard
for premium quality, high-efficiency
combi boilers.
On the primary
heat exchanger*
End user benefits
•Heat exchanger delivers high efficiency
and reliability
•Energy-saving anti-cycle and
modulation control
•Fully modulating pump for reduced
electricity consumption and quieter
operation
•Condenses in CH and DHW mode, resulting
in greater efficiency and fuel savings
•Low electrical consumption when in
standby mode
•Includes internal keyed filling link
•Optional Worcester Keyless Filling Link
available as an upgrade, making system
re-pressurisation easy
•5 year guarantee on plate heat exchanger*
•10 year guarantee on Worcester primary
heat exchanger*
•Boiler protection plans available
•Part of the Which? Best Buy range for
gas-fired condensing boilers.
The Greenstar CDi Classic boiler is
recommended by the Energy Saving
Trust (EST). The Energy Saving Trust
is a non-profit organisation that
provides free and impartial advice
on how to save energy.
WB5
Heat Exchanger

Inside story – Greenstar CDi Classic
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Down firing low NOx burner
Pre-mix fan
Automatic air vent (hidden)
Pressure gauge
Modulating pump
Diverter valve
Drain point
Expansion vessel
Gas valve
Condensate siphon
Aluminium/Silicon primary
WB5 heat exchanger
Secondary DHW plate heat exchanger
Central heating
temperature control
On/off
button
Mains
indicator
Digital
display
Domestic
hot water
temperature control
Greenstar CDi Classic fascia with optional
DT10RF fitted
Optional
programmer
Pressure
gauge

1111
Technical data
Boiler Greenstar
29CDi Classic
Greenstar
34CDi Classic
Greenstar
38CDi Classic
Greenstar
42CDi Classic
Height 760mm (max) 760mm (max) 760mm (max) 760mm (max)
Width 440mm 440mm 440mm 440mm
Depth 360mm (max) 360mm (max) 360mm (max) 360mm (max)
Weight – lift 47.5kg 47.5kg 47.5kg 47.5kg
2005 SEDBUK value – natural gas 90.1% / A rated 90.1% / A rated 90.2% / A rated 90.2% / A rated
2005 SEDBUK value – LPG 92% / A rated 92% / A rated 91.9% / A rated 92.2% / A rated
2009 SEDBUK value – natural gas 89.1% 89.1% 89.0% 89.4%
2009 SEDBUK value – LPG 90.1% 90.1% 90.0% 90.4%
Heating flow / return connections
(compression) 22mm 22mm 22mm 22mm
Hot / cold water connections
(compression) 15mm 15mm 15mm 15mm
Pressure relief valve (compression) 15mm 15mm 15mm 15mm
Condensate connection (plastic pipe) 22mm 22mm 22mm 22mm
Gas connection (compression) 22mm 22mm 22mm 22mm
Primary water content 3.75 ltr 3.75 ltr 3.75 ltr 3.75 ltr
Minimum domestic inlet pressure
for maximum DHW flow rate 1.4bar 1.5bar 1.7bar 1.9bar
Minimum domestic inlet pressure
to operate the appliance 0.2bar 0.2bar 0.2bar 0.2bar
Maximum domestic inlet pressure 10bar 10bar 10bar 10bar
Minimum flow rate to
operate the appliance 1.9 ltr/min 1.9 ltr/min 1.9 ltr/min 1.9 ltr/min
DHW flow rate @ 35ºC∆T† 12.3 ltr/min 14.3 ltr/min 16.4 ltr/min 17.2 ltr/min
DHW flow rate @ 40ºC∆T†† 11 ltr/min 12 ltr/min 14 ltr/min 15 ltr/min
Output to central heating (natural gas) 7.7 - 30kW 7.7 - 30kW 9.4 - 30kW 9.4 - 30kW
Wall mounting jig 9999
Filling link 9999
Plug-in timers 9(optional) 9(optional) 9(optional) 9(optional)
Optimising room
temperature controller 9(optional) 9(optional) 9(optional) 9(optional)
Intelligent controls 9(optional) 9(optional) 9(optional) 9(optional)
Condensing in DHW mode 9999
Maximum vertical flue
(100mm dia.) inc. terminal 9,400mm 8,000mm 7,500mm 7,500mm
Maximum vertical flue
(125mm dia.) inc. terminal 18,500mm 16,000mm 16,000mm 16,000mm
Maximum horizontal flue
(100mm dia.) 7,900mm 7,000mm 6,000mm 6,000mm
Maximum horizontal flue
(125mm dia.) 18,500mm 16,000mm 12,500mm 12,000mm
NOx classification – natural gas 33.3mg/kWh 33.3mg/kWh 21.8mg/kWh 21.8mg/kWh
NOx class 5555
Ingress protection (IP) X4D X4D X4D X4D
†Values for industry comparisons. ††Designed operational flow rate.

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Greenstar CDi Compact
Features and benefits
Greenstar CDi Compact is
available with DHW flow rates
of 11.4, 13.1 and 14.7 l/min
Installation benefits
•Robust, metal wall-mounting jig for safe,
secure, hassle-free fixing
•Split jig design for optimum lift weight.
The expansion vessel has a simple drop
lock mechanism that connects directly
onto the hydraulic unit
•LCD boiler display for operation
status, commissioning features and
diagnostics data
•
Double-seal siphon located at the front
of the boiler for easy maintenance
•Electrical connections accessible from the
front of the boiler
•Maximum flue lengths of 6m 60/100mm
flue and 15m 80/125mm flue
•Pre-set combustion settings for fast
commissioning and with Benchmark
Commissioning Checklist data available on
the boiler display
•Full range of Condensfit II™ horizontal and
vertical flue options with optional plume
management kit available.
Environmental benefits
•SEDBUK A rating of 90.5% (2005 value)
•Ability to fix a maximum heating
temperature – meaning no matter how
much you turn the dial, the temperature
will not exceed that maximum setting
•Precision engineered WB7 heat
exchanger reduces raw material
usage during manufacturing
•All boilers and components are
100% recyclable
•Low electrical standby consumption
•NOx emissions of 35mg/kWh –
achieves 3 credits under the Code
for Sustainable Homes
•Hot water pre-heat accessory (Part
Number 7 716 192 735) allows it to
be used in conjunction with other
heat sources, such as Greenskies
solar thermal
•All boilers and components are 100%
recyclable, achieving Worcester’s zero
waste to landfill objective.
The revolutionary Worcester Greenstar CDi Compact is the newest
addition to our top-of-the-range CDi boiler series and is part of our next
generation of wall-mounted combi boilers. Suitable for small, medium
and large-sized properties with one or two bathrooms, the Greenstar
CDi Compact, with hot water outputs of up to 36kW, is best suited to
properties that demand high outputs from an appliance that can fit
within a standard kitchen cupboard.
Available with DHW flow rates of 11.4, 13.1 and 14.7 l/min, the CDi
Compact is the smallest and most efficient wall mounted condensing
combi boiler Worcester has produced and comes with a host of design
features for ease of installation, use and servicing.
Its ease of installation and cupboard size dimensions are thanks to the
new ultra-compact WB7 heat exchanger, easy-access hydraulics and colour-
coded wiring connectors. The boiler comes supplied with an innovative
wall-mounting jig that allows installers to easily pre-plumb the condensate,
CH flow, DHW outlet, gas, DCW inlet, PRV installer connection & CH return
without the boiler being on the wall.
The Greenstar CDi Compact achieves an A rated annual efficiency of
90.5% (SEDBUK 2005 value) and, along with its low NOx emissions,
obtains 3 credit points within the Code for Sustainable Homes standard.
NEW

13
*The friction stir welding process is used under license from The Welding Institute. †Terms and conditions apply.
End user benefits
•Simple and intelligent control options
available, optimising boiler efficiency and
fuel consumption
•Condenses in CH and DHW mode, resulting
in greater efficiency and fuel savings
•Comfort and ECO modes to suit hot water
delivery needs
•Fully modulating pump for reduced
electricity consumption and quieter
operation
•Built-in frost protection of the boiler and
the surrounding pipes
•Includes internal keyed filling link
•Optional Worcester Keyless Filling Link
available as an upgrade, making system
re-pressurisation easy
•5 year guarantee on plate heat exchanger†
•10 year guarantee on Worcester primary
heat exchanger†
•Boiler protection plans available.
WB7 heat exchanger
At the heart of the Greenstar CDi
Compact is the ground-breaking
WB7 heat exchanger, which uses
advanced friction stir welding*
to create more passageways than
traditional heat exchangers. These
channels provide more efficient
circulation, resulting in a more
effective heat transfer and
quieter operation.
Designed, tested and manufactured
within Bosch Thermotechnology
Ltd., the WB7 heat exchanger
delivers high output despite its
compact size.
Friction stir welding
Friction stir welding is a solid state
machining process where the metal
is softened rather than melted,
giving improved quality, reliability
and performance.
Widely used for demanding
applications in the aviation, marine
and automotive sectors, it has
enabled Worcester to manufacture
a more compact heat exchanger,
reducing the overall size of the
boiler while delivering a high power
ratio of up to maximum 36kW.
To view a video of the friction
stir welding* process, please visit
www.worcester-bosch.co.uk/
stir-welding-video
On the primary
heat exchanger†
The Greenstar CDi Compact boiler is
recommended by the Energy Saving
Trust (EST). The Energy Saving Trust
is a non-profit organisation that
provides free and impartial advice
on how to save energy.
WB7
Heat Exchanger

14
Inside story – Greenstar CDi Compact
Secondary DHW plate
heat exchanger
Fan
Expansion vessel
(hidden)
Gas valve
Condense trap
PCB board
Pressure
relief valve
Diverter valve
(hidden)
Modulating pump
Aluminium/
silicon primary
WB7 heat
exchanger
Greenstar CDi Compact fascia with optional
FW100 weather compensation controller fitted
Optional
programmer
Central heating
temperature control Digital display
Domestic hot
water temperature
control
Pressure
gauge
Mains
indicator
Main cable

15
Technical data
Boiler Greenstar
28CDi Compact
Greenstar
32CDi Compact
Greenstar
36CDi Compact
Height 680mm* 680mm* 680mm*
Width 390mm 390mm 390mm
Depth 280mm 280mm 280mm
Weight – lift 32.9kg 32.9kg 32.9kg
2005 SEDBUK value – natural gas 90.5% / A rated 90.5% / A rated 90.5% / A rated
2005 SEDBUK value – LPG 92.6% / A rated 92.6% / A rated 92.6% / A rated
2009 SEDBUK value – natural gas 89.8% 89.8% 89.8%
2009 SEDBUK value – LPG 90.9% 90.9% 90.9%
Heating flow / return connections
(compression) 22mm 22mm 22mm
Hot / cold water connections
(compression) 15mm 15mm 15mm
Pressure relief valve (compression) 15mm 15mm 15mm
Condensate connection (compression) 22mm 22mm 22mm
Gas connection (compression) 22mm 22mm 22mm
Primary water content 2.2 ltr 2.2 ltr 2.2 ltr
Minimum domestic inlet pressure
for maximum DHW flow rate 1.6bar 1.6bar 1.6bar
Minimum domestic inlet pressure
to operate the appliance 0.2bar 0.2bar 0.2bar
Maximum domestic inlet pressure 10.0bar 10.0bar 10.0bar
DHW flow rate @ 35ºC∆T† 11.4 ltr/min 13.1 ltr/min 14.7 ltr/min
DHW flow rate @ 40ºC∆T†† 10.0 ltr/min 11.5 ltr/min 12.9 ltr/min
Output to central heating 7.03 - 24kW 7.03 - 24kW 7.03 - 24kW
Wall mounting jig 999
Filling link 999
Plug-in timers 9(optional) 9(optional) 9(optional)
Optimising room
temperature controller 9(optional) 9(optional) 9(optional)
Intelligent controls 9(optional) 9(optional) 9(optional)
Condensing in DHW mode 999
Maximum vertical flue
(100mm dia.) inc. terminal 6,000mm 6,000mm 6,000mm
Maximum vertical flue
(125mm dia.) inc. terminal 15,000mm 15,000mm 15,000mm
Maximum horizontal flue
(100mm dia.) 6,000mm 6,000mm 6,000mm
Maximum horizontal flue
(125mm dia.) 15,000mm 15,000mm 15,000mm
NOx classification – natural gas 35mg/kWh 35mg/kWh 35mg/kWh
NOx class 555
Ingress protection (IP) X4D X4D X4D
*690mm to top of casing curve. †Values for industry comparisons. ††Designed operational flow rate

16
Greenstar Si Compact is
available with DHW flow
rates of 10.2 and 12.3 l/min
Greenstar Si Compact
Features and benefits
The Greenstar Si Compact is the successor to the Greenstar Si combi boiler.
The all new Greenstar Si Compact has a host of performance-enhancing
features, including the revolutionary WB7 heat exchanger which enables the
appliances to deliver DHW flow rates of 10.2 and 12.3 l/min despite their
compact size.
Similarly to the CDi Compact, particular care has been taken with the design
of the hydraulic unit. Key components are positioned to provide easy access,
whilst the Heatronic 4i control box makes commissioning simpler. This menu-
driven unit features an LCD display which shows boiler status symbols and
system and commissioning parameters as well as giving access to service and
maintenance codes and diagnostics.
Building on installer feedback, the new Greenstar Si Compact has been
designed to make installation and commissioning easier and quicker and
comes supplied with a unique wall-mounting jig which enables the installer
to quickly pre-plumb all seven pipe connections without the boiler being
on the wall.
The Greenstar Si Compact offers an A rated annual efficiency of up to
90.5% (SEDBUK 2005 value).
Installation benefits
•Can be installed in a standard kitchen
cupboard or compartment without the
need for ventilation
•Robust, metal wall mounting jig for safe,
secure, hassle-free fixing
•Split jig design for optimum lift weight
(32.9kg). The expansion vessel has
a simple drop lock mechanism that
connects directly onto the hydraulic unit
•LCD boiler display for operation status,
commissioning features and diagnostics
•
Double seal siphon located at the front
of the boiler for easy maintenance
•Electrical connections accessible from the
front of the boiler
•Maximum flue lengths of 6m 60/100mm
flue and 15m 80/125mm flue
•Pre-set combustion settings for fast
commissioning and with Benchmark
Commissioning Checklist data available
on the boiler display
•Full range of Condensfit II™ horizontal and
vertical flue options with optional plume
management kit available.
Environmental benefits
•SEDBUK A rating of 90.5% (2005 value)
•Precision engineered heat exchanger
delivers high efficiency and reliability
•Anti-cycle and modulation control
•Simple and intelligent control
options available
•Low electrical consumption when in
standby mode
•Lower fan speed at higher output
•NOx emissions of 35mg/kWh –
achieves 3 credits under the Code
for Sustainable Homes
•All boilers and components are 100%
recyclable, achieving Worcester’s zero
waste to landfill objective.
NEW

17
WB7 heat exchanger
Greenstar Si Compact boilers use
the same ground-breaking WB7
heat exchanger as CDi Compact
appliances.
Although compact in size, the WB7
heat exchanger offers outstanding
levels of performance and is
designed and built to provide
long-term reliability.
Innovation at its best
The WB7 heat exchanger is an
industry first for Worcester, Bosch
Group. State-of-the-art friction
stir welding† technology improves
reliability, as the welding method
eliminates the risk of potential
weak points and stress fractures
occurring.
To view a video of the friction
stir welding† process, please visit
www.worcester-bosch.co.uk/
stir-welding-video
End user benefits
•Highly reliable and efficient
heat exchanger
•Condenses in CH and DHW mode, resulting
in greater efficiency and fuel savings
•Energy-saving anti-cycle and
modulation control
•Simple and intelligent control options
available, optimising boiler efficiency
and fuel consumption
•EMS-BUS compatibility enables use with
Worcester intelligent controls series
•Comfort and ECO modes to suit hot water
delivery needs
•Maximum central heating output 24kW
•Includes internal keyed filling link
•Optional Worcester Keyless Filling
Link available, making system
re-pressurisation easy
•5 year guarantee on plate heat exchanger*
•10 year guarantee on Worcester primary
heat exchanger*
•Boiler protection plans available.
†The friction stir welding process is used under license from The Welding Institute. *Terms and conditions apply.
The Greenstar Si Compact boilers are
recommended by the Energy Saving
Trust (EST). The Energy Saving Trust
is a non-profit organisation that
provides free and impartial advice on
how to save energy.
On the primary
heat exchanger*
WB7
Heat Exchanger

18
Greenstar Si Compact fascia with optional
MT10 mechanical timer fitted
Optional
programmer
Central heating
temperature control Digital display
Domestic hot
water temperature
control
Pressure
gauge
Mains
indicator
Secondary DHW plate
heat exchanger
Fan
Expansion vessel
(hidden)
Gas valve
Condense trap
PCB Board
Pressure
relief valve
Diverter valve
(hidden)
Circulating pump
Aluminium/
Silicon primary
WB7 heat
exchanger
Inside story – Greenstar Si Compact
Main cable
pre-wired to
control board

1919
Technical data
Boiler Greenstar
25Si Compact
Greenstar
30Si Compact
Height 690mm (max)* 690mm (max)*
Width 390mm 390mm
Depth 280mm (max) 280mm (max)
Weight – lift 32.9kg 32.9kg
2005 SEDBUK value – natural gas 90.5% / A rated 90.5% / A rated
2005 SEDBUK value – LPG 92.6% / A rated 92.6% / A rated
2009 SEDBUK value – natural gas 89.8% 89.8%
2009 SEDBUK value – LPG 90.9% 90.9%
Heating flow / return connections (compression) 22mm 22mm
Hot / cold water connections (compression) 15mm 15mm
Pressure relief valve (compression) 15mm 15mm
Condensate connection (plastic pipe) 22mm 22mm
Gas connection (compression) 22mm 22mm
Primary water content 2.2 ltr 2.2 ltr
Minimum domestic inlet pressure
for maximum DHW flow rate 1.6bar 1.6bar
Minimum domestic inlet pressure
to operate the appliance 0.2bar 0.2bar
Maximum domestic inlet pressure 10bar 10bar
Minimum flow rate to operate the appliance 2 ltr/min 2 ltr/min
DHW flow rate @ 35ºC∆T† 10.2 ltr/min 12.3ltr/min
DHW flow rate @ 40ºC∆T†† 8.9 ltr/min 10.7 ltr/min
Output to central heating (natural gas) 7.03 - 24kW 7.03 - 24kW
Wall mounting jig 99
Filling link 9(optional) 9(optional)
Plug-in timers 9(optional) 9(optional)
Optimising room temperature controller 9(optional) 9(optional)
Intelligent controls 9(optional) 9(optional)
Condensing in DHW mode 99
Maximum vertical flue (100mm dia.) inc. terminal 6,000mm 6,000mm
Maximum vertical flue (125mm dia.) inc. terminal 15,000mm 15,000mm
Maximum horizontal flue (100mm dia.) 6,000mm 6,000mm
Maximum horizontal flue (125mm dia.) 15,000mm 15,000mm
NOx classification – natural gas 35mg/kWh 35mg/kWh
NOx class 55
Ingress protection (IP) X4D X4D
*Measured to the top or front of the curve height. †Values for industry comparisons. ††Designed operational flow rate.

20
Greenstar i Junior
Features and benefits
With more than 1 million boilers already installed in the UK, the well-
established award-winning Greenstar i Junior condensing boiler series,
with outputs of 24kW and 28kW are ideal for apartments and small to
medium-sized properties with one bathroom.
Greenstar i Junior appliances have DHW flow rates of 9.8 and 11.4 l/min,
making them suitable for a variety of locations, including kitchens, utility
rooms, bathrooms, airing cupboards, lofts or garages. They now feature a
number of enhancements including the addition of a DHW control to the
boiler fascia and the ability to be used with Worcester intelligent controls
for load and weather compensation. Switch mode power supply reduces
energy consumption in standby by 61% and lift weight by almost 1kg.
The Greenstar i Junior appliances come supplied with a pre-assembled
light weight wall frame, that has pre-drilled fixing points and options that
make hanging the appliance quick and easy. The wall-mounting jig allows
installers to quickly pre-plumb the condensate, CH flow, DHW outlet, gas,
DCW inlet, PRV installer connection & CH return without the boiler being
on the wall. Both models offer an A rated annual efficiency of up to 90.1%
(SEDBUK 2005 value).
Installation benefits
•Small dimensions
•Class-leading lift weight 26kg
•Split wall-mounting jig design for a
simple installation
•Robust, metal wall frame provided
as standard, allowing space for
pipes behind the boiler
•Split wall-mounting jig provided as
standard for pre-plumbing of all
7 connections – gas, water, PRV
and condensate connections
before the boiler is on the wall
•Vertical pre-piping assembly is
available as an accessory
•Full range of Condensfit II™
horizontal and vertical flue options
with optional plume management
kit available.
Environmental benefits
•SEDBUK A rating of 90.1%
(2005 value)
•EMS BUS enabled to allow
intelligent and weather
compensation controls to be used
•Reduced energy consumption with
switch mode power supply
•WB3 heat exchanger delivers high
efficiency and reliability
•Anti-cycle and modulation control
•Intelligent and on/off control
options available
•Low electrical consumption when
in standby mode
•Both models achieve 3 credits
under the Code for Sustainable
Homes when the optional Low
NOx Code Plug is fitted
•All boilers and components
are 100% recyclable, achieving
Worcester’s zero waste to
landfill objective.
The Greenstar i Junior has
DHW flow rates of 9.8 and
11.4 l/min
NEW