Worcester GREENSTAR 24i junior User manual

THE APPLIANCE IS FOR USE WITH
NATURAL GAS OR L.P.G. (Cat II 2H3P TYPE C13 & C33)
NATURAL GAS:
WORCESTER GREENSTAR 24i junior GC NUMBER 47-311-86
WORCESTER GREENSTAR 28i junior GC NUMBER 47-311-87
LIQUID PETROLEUM GAS:
WORCESTER GREENSTAR 24i junior GC NUMBER 47-311-90
WORCESTER GREENSTAR 28i junior GC NUMBER 47-311-91
GB/IE
CHECKLIST & service
interval record, printed within this
manual

SYMBOLS USED IN THIS MANUAL:
WORCESTER:
TECHNICAL: 08705 266241
SERVICE: 08457 256206
SPARES: 01905 752571
LITERATURE: 01905 752556
TRAINING: 01905 752526
SALES: 01905 752640
WEBSITE: www.worcester-bosch.co.uk
WATER TREATMENT:
FERNOX 01799 550811
www.fernox.com
SENTINEL 0151 420 9595
www.betzdearborn.com/sentinel
FLUE TERMINAL GUARD:
TOWER FLUE COMPONENTS
VALE RISE
TONBRIDGE
TN9 1TB
TEL: [phone]
FAX: [phone]
PLEASE READ THESE INSTRUCTIONS CAREFULLY BEFORE STARTING INSTALLATION.
THESE INSTRUCTIONS ARE APPLICABLE TO THE WORCESTER APPLIANCE MODEL(S)
STATED ON THE FRONT COVER OF THIS MANUAL ONLY AND MUST NOT BE USED WITH
ANY OTHER MAKE OR MODEL OF APPLIANCE.
THE INSTRUCTIONS APPLY IN THE UK ONLY AND MUST BE FOLLOWED EXCEPT FOR ANY
STATUTORY OBLIGATION.
THIS APPLIANCE MUST BE INSTALLED BY A COMPETENT PERSON. FAILURE TO INSTALL
CORRECTLY COULD LEAD TO PROSECUTION.
IF YOU ARE IN ANY DOUBT CONTACT THE WORCESTER TECHNICAL HELPLINE.
DISTANCE LEARNING AND TRAINING COURSES ARE AVAILABLE FROM WORCESTER.
PLEASE LEAVE THESE INSTRUCTIONS WITH THE COMPLETED BENCHMARK
CHECKLIST, (OR A CERTIFICATE CONFIRMING COMPLIANCE WITH IS 813, EIRE ONLY)
AND THE USER MANUAL WITH THE OWNER OR AT THE GAS METER AFTER INSTALLA-
TION OR SERVICING. THE BENCHMARK CHECKLIST CAN BE FOUND IN THE BACK TWO
PAGES OF THE INSTALLATION MANUAL.
ABBREVIATIONS USED IN THIS MANUAL:
Ø Diameter
NG Natural Gas
LPG Liquid Petroleum Gas
CH Central Heating
DHW Domestic Hot Water
IP Ingress Protection
SEDBUK Seasonal Efficiency of Domestic Boilers in the United Kingdom
CONTACT INFORMATION INSTALLATION & SERVICING INSTRUCTIONS
LIFTING AND CARRYING PRECAUTIONS:
• Lift only a manageable weight, or ask for
help.
• When lifting the boiler, bend the knees,
and keep the back straight and feet apart.
• Do not lift and twist at the same time.
• Lift and carry the boiler close to the body
• Wear protective clothing and gloves to
protect from any sharp edges
INSTALLATION &
SERVICING INSTRUCTIONS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 107 336b (11/05)
1
STORE THE APPLIANCE IN A DRY
AREA PRIOR TO INSTALLATION.

SAFETY & REGULATIONS
SAFETY PRECAUTIONS & SYMBOLS 3
INSTALLATION REGULATIONS 3
APPLIANCE INFORMATION
GENERAL INFORMATION 4
TECHNICAL DATA 5
LAYOUT & COMPONENTS 6-7
PRE-INSTALLATION
CLEANING PRIMARY SYSTEMS 8
MAINS SUPPLY 9
WATER SYSTEMS & PIPEWORK 10
CONDENSATE PIPEWORK 11
PRESSURE RELIEF PIPEWORK 12
BOILER LOCATION & CLEARANCES 13-14
PLUMBING MANIFOLD 15
FLUE TERMINAL POSITIONS 16
FLUE OPTIONS 17
INSTALLATION
UNPACKING THE WALL FRAME 18
WALL MOUNTING TEMPLATE / FLUE OPENING 19
UNPACKING THE APPLIANCE 20
BOILER CONNECTIONS 21-22
FLUE INSTALLATION 23-25
CONDENSATE CONNECTIONS 26
ELECTRICS 27
POSITION OF WIRED COMPONENTS 28
COMMISSIONING
PRE-COMMISSIONING CHECKS 29
FILLING THE SYSTEM 30
STARTING THE APPLIANCE 31
WATER TREATMENT 32
COMMISSIONING 33
FINISHING COMMISSIONING 34
SERVICING & SPARES
INSPECTION AND SERVICE 35-40
REPLACEMENT OF PARTS 41-50
SETTING THE GAS/AIR RATIO 51
SHORT PARTS LIST 52
CONVERSION KITS
L.P.G. CONVERSION 53
FAULT FINDING & DIAGNOSIS
FAULT FINDING 54
CH FUNCTION 55
DHW FUNCTION 56
PROTECTION FUNCTION 57-58
BENCHMARK CHECKLIST
SERVICE INTERVAL RECORD SHEET
CONTENTS
CONTENTS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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2
SAFETY &
REGULATIONS
APPLIANCE
INFORMATION
PRE -
INSTALLATION
INSTALLATIONCOMMISSIONING
SERVICING
& SPARES
CONVERSION
KITS
FAULT FINDING
& DIAGRAMS

SAFETY PRECAUTIONS
& INSTALLATION REGULATIONS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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3
SAFETY &
REGULATIONS
SAFETY PRECAUTIONS INSTALLATION REGULATIONS
IF YOU SMELL GAS:
✗DON’T SMOKE OR STRIKE MATCHES
✗DON’T TURN ELECTRICAL SWITCHES ON OR OFF
✓DO PUT OUT NAKED FLAMES
✓DO OPEN DOORS AND WINDOWS
✓DO KEEP PEOPLE AWAY FROM THE AREA AFFECTED
✓DO TURN OFF THE CONTROL VALVE AT THE METER
✓DO CALL YOUR GAS COMPANY
A Benchmark Checklist is provided by the manufacturer for the installer to complete
including their CORGI registration number to confirm that the boiler has been installed,
commissioned and serviced according to the manufacturer’s instructions.
IMPORTANT: The completed Benchmark Checklist will be required in the event of any
warranty work and may be required by the local Building Control Inspector.
HEALTH & SAFETY
The appliance contains no asbestos and no substances have been used in the
construction process that contravene the COSHH Regulations (Control of Substances
Hazardous to Health Regulations 1988).
COMBUSTIBLE AND CORROSIVE MATERIALS
Do not store or use any combustible materials (paper, thinners, paints etc.) inside or
within the vicinity of the appliance.
Chemically aggressive substances, such as halogenated hydrocarbons containing
chlorine or fluorine compounds can corrode the appliance and invalidate any warranty.
FITTING & MODIFICATIONS
Fitting the appliance and any controls to the appliance may only be carried out by a
competent engineer in accordance with the current Gas Safety (Installation and Use)
Regulations.
Flue systems must not be modified in any way other than as described in the fitting
instructions. Any misuse or unauthorised modifications to the appliance, flue or
associated components and systems could invalidate the warranty. The manufacturer
accepts no liability arising from any such actions, excluding statutory rights.
SERVICING
Advise the user to have the system serviced annually by a competent, qualified
engineer (such as British Gas or CORGI registered personnel) using approved spares,
to help maintain the economy, safety and reliability of the appliance.
IMPORTANT - The service engineer must complete the Service Record on the
Benchmark Checklist after each service.
Gas Safety (Installation & Use) Regulations 1998:
All gas appliances must be installed by a
competent person in accordance with the above
regulations. Failure to install appliances correctly
could lead to prosecution.
The appliance must be installed in accordance
with, and comply to, the current: Gas Safety
Regulations, IEE Regulations, Building
Regulations, Building Standards (Scotland)
(Consolidation), Building Regulations (Northern
Ireland), local water by-laws, Health & Safety
Document 635 (The Electricity at Work
Regulations 1989) and any other local
requirements.
British Standards:
The relevant British Standards should be followed,
including:
BS7074:1 : Code of practice for domestic and hot
water supply
BS6891 : Installation of low pressure gas
pipework up to 28mm (R1)
BS5546 : Installation of gas hot water supplies for
domestic purposes
EN:12828 : Central heating for domestic premises
BS5440:1 : Flues and ventilation for gas appli-
ances of rated heating not exceeding 70kW (net) :
Flues
BS5440:2 : Flues and ventilation for gas appli-
ances of rated heating not exceeding 70kW (net) :
Air Supply
BS7593 : Treatment of water in domestic hot
water central heating systems
BS 6798 : Installation of gas fired boilers of rated
input up to 70kW (net)
Where no specific instruction is given, reference
should be made to the relevant British Standard
codes of Practice.
L.P.G. Installation:
An appliance using L.P.G. must not be installed in
a room or internal space below ground level unless
one side of the building is open to the ground.
Timber framed buildings:
Where the boiler is to be fitted to a timber framed
building the guidelines laid down in BS5440: Part
1 and IGE "Gas Installations in Timber Frame
Buildings” should be adhered to.
Potable water:
All seals, joints and compounds (including flux and
solder) and components used as part of the
secondary domestic water system must be
approved by WRAS.
CH water:
Artificially softened water must not be used to fill
the central heating system.

GENERAL INFORMATION
STANDARD PACKAGE:
A - Wall hung gas fired condensing combi boiler for
central heating and domestic hot water
B - Boiler support frame
C -Hardware literature pack
D - Bottom Panel
SPECIFICATIONS:
Pre-wired and pre-plumbed
Galvanised steel inner frame
Digital control system
Automatic ignition
Direct burner ignition electrodes
Built-in frost thermostat
Built-in fault finding diagnostics
Modulating automatic gas valve
Combustion air fan with speed regulator
CH temperature sensor & control
Pump anti-seizure protection
Flue gas temperature limiter
Condensate trap & syphon
DHW flow sensor
Plate type DHW heat exchanger
700mm
400mm
A
D
330mm
GENERAL INFORMATION
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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4
APPLIANCE
INFORMATION
B
C
D
(When fitted to wall frame)
Depth to wall

TECHNICAL DATA INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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5
TECHNICAL DATA
APPLIANCE
INFORMATION
Domestic Hot Water
Min. heat input KW 7.38 7.38 9.64 9.64
Max. rated heat output KW 24 28 24 28
Max. rated heat input KW 24.49 28.57 24.49 28.57
Gas flow rate - Max. 10 minutes from lighting
Natural Gas G20 m3/h 2.59 3.02 - -
Propane Gas (LPG) kg/h - - 1.9 2.22
Max. mains inlet pressure bar 10 10 10 10
Min. mains inlet pressure (working) for max flow bar 1.3 1.3 1.3 1.3
Min. mains inlet pressure (working) for operation bar 0.2 0.2 0.2 0.2
Domestic Hot Water temperature setting °C 55 55 55 55
Domestic Hot Water specific rate - 30°C rise l/min 11.5 13.4 11.5 13.4
Max. Domestic Hot Water flow rate - 40°C rise +/— 15% l/min 8.6 10 8.6 10
Central Heating
Max. rated heat input KW 24.62 24.62 24.62 24.62
Max. rated heat output 40/30°C KW 25.67 25.67 25.67 25.67
Max. rated heat output 50/30°C KW 25.45 25.45 25.45 25.45
Max. rated heat output 80/60°C KW 24 24 24 24
Max. flow temperature °C 82 82 82 82
Max. permissible operating pressure bar 2.5 2.5 2.5 2.5
Available pump head at 21°C system temperature rise m 2.0 2.0 2.0 2.0
Flue
Flue Gas Temp. 80/60°C, rated/min. load °C 78/63 78/64 79/64 79/65
Flue Gas Temp. 40/30°C, rated min. load °C 54/35 54/36 55/38 55/39
CO2level at max. rated heat output % 9.8 9.8 11.0 11.0
CO2level at min. rated heat output % 9.2 9.2 10.5 10.5
NOx - class 5555
Condensate
Max. condensation rate l/h 2.0 2.0 2.0 2.0
pH value, approx. 4.8 4.8 4.8 4.8
Electrical
Electrical power supply voltage AC...V 230 230 230 230
Frequency Hz 50 50 50 50
Max. power consumption W 140 140 140 140
General Data
SEDBUK band AAAA
Appliance protection rating IP X4D X4D X4D X4D
Appliance protection rating with mechanical or RF mechanical timer fitted IP 20 20 20 20
Permissible ambient temperatures °C 0-50 0-50 0-50 0-50
Nominal capacity of appliance Itr 3.9 3.9 3.9 3.9
Noise output level (Max central heating) dB(A) 42 42 42 42
Packaged boiler weight kg 44.4 44.4 44.4 44.4
Total boiler weight kg 39.5 39.5 39.5 39.5
Lift weight kg 27.1 27.1 27.1 27.1
SEDBUK % 90.1 90.1 91.8 91.8
DESCRIPTION NATURAL GAS L.P.G.
UNITS 24i junior 28i junior 24i junior 28i junior

LAYOUT & COMPONENTS
The diagram opposite shows the controls in the
servicing position and excludes the outer case.
1 AIR / GAS MANIFOLD
2FAN
3 AIR / GAS ADJUSTMENT SCREW
4GASVALVE
5 INLET PRESSURE TEST POINT
6 EXPANSION VESSEL
7 WALL MOUNTING FRAME
8 COVER FOR EXTERNAL WIRING
CONNECTIONS
9 CONDENSATE CONNECTION FROM
HEAT EXCHANGER
10 PLATE TO PLATE
DHW HEAT EXCHANGER
11 FLUE PRESSURE SWITCH
12 FAN PRESSURE TEST POINT
13 MANUAL VENT POINT
14 IGNITION AND FLAME SENSE ELECTRODES
15 OVERHEAT THERMOSTAT
16 FLAME VIEWING MIRROR
17 SECURING NUT, AIR /
GAS MANIFOLD CLAMP
18 SENSOR - BOILER FLOW
19 FLUE AIR PRESSURE SWITCH
CONNECTION
20 FLUE OVERHEAT THERMOSTAT
21 ACCESS POINT FOR CLEANING HEAT
EXCHANGER/SUMP
22 REMOVABLE TOP CASE PANEL FOR
SERVICING
23 GAS INLET CONNECTION 22mm
COMPRESSION
24 TRAP / SYPHON
25 TRAP / SYPHON OUTLET
CONNECTION ( 22mm PLASTIC PIPE)
26 MAINS COLD WATER IN
27 CH FLOW
28 DHW OUT
29 CH RETURN
30 DRAIN POINT
31 SILICONE TUBE (USE TO VENT AIR
FROM HEAT EXCHANGER)
32 PUMP
33 SYSTEM PRESSURE GAUGE
34 CONTROL PANEL IN SERVICE
POSITION
35 HEAT EXCHANGER
36 ACCESS COVER FOR TRANSFORMER &
PCB
LAYOUT & COMPONENTS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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APPLIANCE
INFORMATION

LAYOUT & COMPONENTS
10 PLATE TO PLATE DHW
HEAT EXCHANGER
32 SYSTEM PUMP
36 FLOW TURBINE
37 UNUSED PORT
38 AUTO AIR VENT
39 FLOW CONNECTION FROM BOILER
HEAT EXCHANGER
40 DHW SENSOR
41 CH FLOW CONNECTION TO
SERVICE VALVE
42 DHW OUT CONNECTION
43 COLD WATER IN CONNECTION
44 CH RETURN CONNECTION TO
SERVICE VALVE
45 DIVERTER VALVE
46 PRESSURE RELIEF VALVE
47 COMPACT HYDRAULIC MOUNTING
SCREW (2) TO BOILER
48 CH TEMPERATURE CONTROL
49 MAINS ON/OFF INDICATOR/
DIAGNOSTIC LIGHT (BLUE)
50 SERVICE MODE BUTTON
51 BURNER ON INDICATOR LIGHT (GREEN)
52 MASTER SWITCH ON/OFF
53 ECO BUTTON
54 FAULT RESET BUTTON
55 SYSTEM PRESSURE GAUGE
56 POSITION FOR OPTIONAL
PROGRAMMER
57 INTERNAL BY-PASS WITHIN
PLASTIC MOULDING
LAYOUT & COMPONENTS INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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7
APPLIANCE
INFORMATION

CLEANING PRIMARY SYSTEMS
BEFORE CLEANING THE SYSTEM:
ENSURE THE SYSTEM AND PIPEWORK IS
IN GOOD WORKING ORDER
KEEP THE EXISTING BOILER/
CIRCULATING PUMP WHERE POSSIBLE
OR USE A POWER FLUSHING MACHINE
TO AID THE CLEANSING PROCEDURE
BEFORE INSTALLING A NEW BOILER.
CLEANING THE PRIMARY SYSTEM:
1 Fill the system with cold water and
check for leaks.
2 Open all drain cocks and drain the
system.
3 Close drain cocks and add a suitable
flushing agent compatible with
aluminium at the correct strength for
the system condition in accordance with
the manufacturer's instructions.
The PH value of the system water
must be less than 8 or the appliance
guarantee will be invalidated.
Circulate the flushing agent before the
boiler is fired up.
4 Run the boiler/system at normal operating
temperature as directed by the manufacturer
of the flushing agent.
5 Drain and thoroughly flush the system to
remove the flushing agent and debris.
IMPORTANT: All the following Pre-Installation sections must be read and
requirements met before starting boiler or flue installation.
CAUTION: ISOLATE THE MAINS SUPPLIES BEFORE STARTING ANY WORK AND
OBSERVE ALL RELEVANT SAFETY PRECAUTIONS.
IMPORTANT: Debris from the system can
damage the boiler and reduce efficiency.
Failure to comply with the guidelines for
the use of water treatment with the
appliance will invalidate the appliance
warranty.
CLEANING PRIMARY SYSTEMS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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8
PRE -
INSTALLATION

MAINS SUPPLY
ELECTRIC SUPPLY:
• Supply: 230V - 50Hz, 140 watts
• Cable: PVC insulated 0.75mm2(24 x 0.2mm)
temperature rated to 90°C.
• External 3A fuse to BS1362.
• The appliance must be earthed.
• IPX4D. NOTE: this is reduced to IP20 if the
following mechanical timers are fitted:
7 716 192 036 or 7 716 192 037.
• All pipes to the boiler must be cross-bonded.
• Wiring must comply with IEE wiring regulations.
GAS SUPPLY:
• Boilers using NG must be connected to a
governed meter.
• LPG boilers must be connected to a
regulator.
• Installation and connection of the gas supply
to the boiler must be in accordance with
BS6891.
• Under no circumstances should the size of
the gas supply pipe be less than that of the
appliance inlet connection.
• The meter or regulator and pipework to the
meter must be checked, preferably by the gas
supplier, to ensure it is in good working order
and can meet the gas flow and pressure
requirements in addition to the demand from
any other appliance being served.
WATER SUPPLY:
Water mains pressure:
• Minimum mains water pressure 1.3 bar for
maximum performance.
• Maximum mains fed water pressure 10 bar.
If necessary, fit a pressure reducing valve.
• Where the mains water supply has a non-
return, back flow prevention valve fitted, a
mini expansion vessel (A) should be connect-
ed to the mains water inlet pipe (B) between
the non-return valve (C) and the boiler (D) as
shown opposite.
Use in hard water areas:
Normally there is no need for water treatment to
prevent scale formation as the maximum tem-
perature of the DHW heat exchanger is limited
in the electronic circuit.
In areas where temporary water hardness
exceeds 200ppm, consideration may need to
be given to the fitting of a scale prevention
device. In such circumstances, the advice of
the local water authority should be sought.
IMPORTANT: Non-return, back flow pre-
vention devices (including those associ-
ated with water meters) fitted to the
mains water supply can cause a pres-
sure build up which could damage the
boiler and other household appliances.
MAINS SUPPLY INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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PRE -
INSTALLATION
MAINS WATER EXPANSION VESSEL:
A - Mini expansion vessel, part No. 7 716 102 105
B - Mains water inlet
C - Non-return valve
D - Boiler
A
BC
D

WATER SYSTEMS & PIPEWORK
PLASTIC PIPEWORK:
• Any plastic pipework must have a polymeric
barrier with 600mm (minimum) length of
copper or steel pipe connected to the boiler.
• Plastic pipework used for underfloor heating
must be correctly controlled with a
thermostatic blending valve limiting the
temperature of the circuits to approx. 50°C.
The pipework from the boiler to the blending
valve must be in copper or steel (protected
from corrosion).
PRIMARY SYSTEMS CONNECTIONS/VALVES:
• All system connections, taps and mixing
valves must be capable of sustaining a
pressure up to 3 bar.
• Radiator valves should conform to
BS2767:10.
• All other valves should conform to BS1010.
• Thermostatic radiator valves (TRV’s) must be
used on all radiators within the sleeping
accommodation but not the radiator where
the room thermostat is sited. This must be
fitted with lockshield valves and left open.
• A drain cock is required at the lowest point
in the system.
• An air vent is required at all the high points in
the system.
NOTE: The boiler is equipped with an automatic
internal by-pass.
SHOWERS/BIDETS:
• If a shower head can be immersed in water or
comes closer than 25mm from the top edge
of a bath or shower tray spill over level then
an anti-siphon device must be fitted to the
shower hose.
• Bidets with direct hot and cold mains water
can be used (with the approval of the local
water authority) and must be the over rim
flushing type with shrouded outlets to prevent
the fitting of hand held sprays.
SEALED PRIMARY SYSTEM:
• The CH sealed system must be filled using a
WRAS approved filling loop or comply with
the diagram opposite for system fill.
• Where the system volume is more than 100
litres or exceeds 2.65 bar at maximum
heating temperature, an extra expansion
vessel (B) must be fitted as close as possible
to the appliance in the central heating return.
• Pressurise the extra expansion vessel (B) to
the same figure as the expansion vessel built
into the appliance.
•Do not use galvanised pipes or radiators.
INSTALLATIONCOMMISSIONING
TYPICAL SEALED SYSTEM
A - Appliance expansion vessel -
central heating
B - Extra expansion vessel -
central heating return
C - Drain cock
P - Pressure relief discharge
R - Radiators
SYSTEM FILL
B
A
PC
C
RR
RR
WATER SYSTEMS & PIPEWORK
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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PRE -
INSTALLATION

CONDENSATE PIPEWORK
CONDENSATE PIPEWORK:
• The condensate pipe must be a minimum of
22mmØ plastic pipe.
•The condensate pipework must fall at
least 50mm per metre towards the outlet
and should take the shortest practicable
route.
• The pipework must follow one of the options
shown opposite into an internal serviceable
trap (min. 75mm) such as a sink/washing
machine) or discharge direct into a vent
stack (E) 450mm min. above pipe invert or
into a gulley (D) below ground but above the
water level.
•Use waterproof pipe insulation in exposed
positions and for external pipework.
1 Internal sink/washing machine drain
2 Internal waste drainage system
3 Soil/vent stack
4 External drainage system
5 External condensate absorption point
A - Condensate from boiler
B - Sink
C - 22mmØ plastic condensate pipe
D - Gulley
E - Internal soil and vent stack
F - Serviceable waste trap (75mm min)
G - 300mm x 100mmØ sealed plastic tube
H - Ground level
J - Drainage holes 50mm from base of tube
(12mmØ at 25mm centres) facing away from
building
K - Limestone chippings
IMPORTANT: Ensure there are no
blockages in the pipe run.
CONDENSATE PIPEWORK INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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11
PRE -
INSTALLATION

PRESSURE RELIEF PIPEWORK
PRESSURE RELIEF PIPEWORK:
• The pressure relief drain pipe (M) from the
boiler should be at least 15mm diameter
copper pipe and run downwards away from
any electrics or other hazard, preferably to an
external drain or soakaway.
• Pipe (M) should be finished with a partial
bend, near the outlet to face the external wall
(as shown) to help prevent freezing.
L - Outside wall
O,M - Drain pipe
N - External drain
IMPORTANT: The pressure relief valve
is a safety device for the boiler and if
activated may discharge boiling water
steam through the relief valve drain
pipe.
Care should be taken when siting the
outlet pipe so that it does not cause an
obstruction or discharge above a
window, entrance or other public access
where it could cause a hazard.
PRESSURE RELIEF PIPEWORK
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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PRE -
INSTALLATION
M
N
O
L

BOILER LOCATION & CLEARANCES INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
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PRE -
INSTALLATION
BOILER LOCATION &
CLEARANCES
This boiler is only suitable for installing internally
within a property at a suitable location onto a
fixed, rigid non-combustible surface at least the
same size as the boiler and capable of support-
ing the boiler weight.
COMPARTMENTS:
Follow the requirements of BS6798 and
BS5440 Part 2 and note:
• Minimum clearances must be maintained
• An access door is required to install, service
and maintain the boiler and any ancilliary
equipment.
• If fitting the boiler into an airing cupboard
use a non-combustible perforated material
(maximum hole sizes of 13mm) to separate
the boiler from the airing space.
BOILER CLEARANCES:
The diagram opposite shows the minimum
space required to install and service the boiler.
If a boiler is installed in a compartment with
clearances less than shown in the tables oppo-
site, ventilation is required. Refer to tables
below for ventilation requirements.
BOILER CLEARANCES - UNVENTILATED
COMPARTMENTS:
The tables opposite show the options for the
minimum space required to install and service
the boiler inside an unventilated compartment.
24 & 28 kW
Vent To room or Direct to
position internal space outside
High Minimum free Minimum
level area 122 cm2free area
61 cm2
Low Minimum free Minimum
level area 122 cm2free area
61cm2
SERVICING CLEARANCES
VENTED COMPARTMENT
VENTILATION FREE COMPARTMENTS
INSTALLATION CLEARANCES
Using 100mm flue kit
1080mm
Using 125mm flue kit
- 1110mm
Ventilation Free Compartments Installation Clearances
The suggested total unventilated compartment minimum clearances are:
Side Above Below Front (to removable door)
400mm 170mm approx. 200mm 100mm
(30mm above
the elbow)
(Note: Top and bottom clearances must not be reduced below these values as they are the
minimum required for servicing).
If Side Clearances are Reduced
350mm 441mm 129mm
300mm 523mm 161mm
250mm 617mm 200mm
200mm 727mm 243mm
150mm 856mm 295mm
100mm 1012mm 358mm
50mm 1202mm 434mm
If total side clearance is
reduced to:
Then overall height clearances
must be increased to (approx): OR Front clearance (to removable
door) must be increased to:
If Front Clearance is Reduced
50mm 511mm 505mm
25mm 596mm 569mm
If front clearance (to
removable door) is
reduced to:
Then overall height clearances
must be increased to (approx): OR Total side clearance must be
increased to:

BOILER LOCATION & CLEARANCES
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 107 336b (11/05)
14
PRE -
INSTALLATION
11
23
2
3
11
23
BATHROOMS:
If the appliance is fitted in conjunction with a
mechanical or RF mechanical timer, the
appliance can only be fitted in zone 3 .
Otherwise the appliance can be fitted in both
zones 2 and 3 .
See IEE wiring regulations.
BOILER LOCATION &
CLEARANCES
IMPORTANT: any switch or appliance
control using mains electricity must not be
able to be touched by a person using the
bath or shower.
Electrical switches, fused spur and socket
outlets must not be situated in the
bathroom.

PLUMBING MANIFOLD
CONNECTIONS:
Heating System: 22mm compression fittings
DHW: 15mm compression fittings
Gas: 22mm compression fittings
Use the fittings supplied in the Lit/Hardware
pack.
• If the boiler pipes are to be run behind the
appliance ensure that the pipes pass through
the slot in the yellow plastic guide (A). This is
fitted to the boiler frame.
*
CH Return 22mm
CH Flow 22mm
PLUMBING MANIFOLD INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 107 336b (11/05)
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PRE -
INSTALLATION
DHW OUT 15mm
DHW IN (alternative from
above appliance)
15mm
Gas Supply (alternative from above appliance) 22mm
Mains Gas Supply 22mm Mains Water (DHW IN) 15mm
A
Further guidance on pipe routing can be
found printed on the boiler template
(supplied with the boiler).

PRE -
INSTALLATION
FLUE TERMINAL POSITIONS
• The flue must be fitted and terminated in
accordance with the recommendations of
BS5440 : Part 1.
• The flue must not cause an obstruction.
• Discharge and any noise from the flue outlet
must not cause a nuisance.
• Flue gases have a tendency to plume and in
certain weather conditions a white plume of
condensation will be discharged from the flue
outlet. This could be a nuisance, for example,
near security lighting.
• The air inlet/outlet duct and the terminal of
the boiler must not be closer than 25mm to
any combustible material.
Detailed recommendations on protection of
combustible materials are given in
BS 5440:1.
• A protective terminal guard must be fitted if
the terminal is 2m or less above a surface
to which people have access.
The guard must be spaced equally (minimum
50mm) around the flue and fixed to the wall
with plated screws.
See Contact Information (inside front cover).
Minimum dimensions of flue terminal positions for balanced room sealed flues with
fanned draught:
DRWG. TERMINAL POSITION DISTANCE
REF:
A1Directly below an opening, air brick, opening windows, etc. 300mm
B1Above an opening, air brick, opening window, etc. 300 mm
C1 Horizontally to an opening, air brick, opening window, etc. 300 mm
D Below gutters, soil pipes or drain pipes 75mm
E Below eaves 200mm
F2Below balconies or car port roof (lowest point) 200mm
G From a vertical drain pipe or soil pipe 150mm
H From internal or external corner or to a boundary alongside the terminal 300mm
I Above ground, roof or balcony 300mm
J From a surface or boundary facing the terminal 600mm
K From a terminal facing the terminal 1200mm
L2From an opening in the car port (e.g. door, window) into the dwelling 1200mm
M Vertically from a terminal on the same wall 1500mm
N Horizontally from a terminal on the same wall 300mm
O From a non combustible vertical structure on the roof
P Above intersection with the roof
1 In addition, the terminal should not be nearer than 150mm (fanned draught)
to an opening in the building fabric formed for the purpose of accommodating
a built-in element such as a window frame.
2 Not recommended.
See instructions supplied with vertical flue kits.
Care should be taken to ensure terminal siting
does not cause a nuisance to adjacent properties.
*
*
*
**
**
**
600mm
600mm
2000mm
Terminals adjacent to windows or openings on pitched
and flat roofs.
The flue should not penetrate
the shaded area.
FLUE TERMINAL POSITIONS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 107 336b (11/05)
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FLUE OPTIONS INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 107 336b (11/05)
17
PRE -
INSTALLATION
FLUE OPTIONS
• The diagrams (opposite) show the
components used and the maximum flue
length for each configuration of 100mm and
125mm flues.
• Shaded flue components indicate the
standard 100mm horizontal flue.
• Only straight flue sections can be reduced in
length and cut.
• The flue terminal end can be fitted from the
inside or outside of the building.
• Fixing kits are supplied with the flue extension
kits.
• Horizontal 125mm and Vertical 100mm and
125mm flue kits are available with separate
instructions. Contact your supplier or
Worcester.
A - Standard horizontal flue (100mm diameter
shown)
B - Straight flue extension
C - Flue bend 90°
D - Flue bend 45°
E - Vertical terminal (vertical adaptor supplied
with terminal)
F - Vertical adaptor (used with horizontal
terminal)
Calculating the flue length:
Measure the total flue length required, noting
that the maximum straight flue length including
the terminal is:
Horizontal 60/100mm: 4600mm
Horizontal 80/125mm: 13000mm
Vertical 60/100mm: 6400mm
Vertical 80/125mm: 15000mm
Then reduce the total straight flue length for
each extra flue bend (excluding the flue elbow)
by:
2000mm for 90°
1000mm for 45°
Flue Extension lengths:
Horizontal & Vertical 60/100mm: 960mm
Horizontal & Vertical 80/125mm: 1000mm
Flue Terminal lengths:
Horizontal 60/100mm: 800mm including terminal
Horizontal 80/125mm: 1200mm including terminal
Vertical 60/100mm: 1140mm to top of terminal
Vertical 80/125mm: 1365mm to top of terminal
STANDARD FLUE HORIZONTAL
Ø100
MAX 686 A x 1
MIN 250 A x 1*
Ø125
MAX 1070 A x 1
MIN 250 A x 1*
* Requires cutting
MAXIMUM FLUE HORIZONTAL
Ø100 - 4600mm
A x 1 + B x 5
Ø125 - 13000mm
A x 1 + B x 13
MAXIMUM FLUE VERTICAL START + 1 BEND
Ø100 - 4600mm
A x 1 + C x 1 + B x 5 +
Fx1
Ø125 - 13000mm
A x 1 + C x 1 + B x 13 +
Fx1
Ø100 - 2600mm
A x 1 + B x 3 + C x 1
Ø125 - 11000mm
A x 1 + B x 11 + C x 1
MAXIMUM FLUE HORIZONTAL + 1 BEND
MAXIMUM FLUE VERTICAL
START + 2 BENDS
Ø100 - 2600mm
A x 1 + C x 2 + B x 4 +
Fx1
Ø125 - 11000mm
A x 1 + C x 2 + B x 13 +
Fx1
Ø100 - N/A
Ø125 - 9000mm
A x 1 + C x 3 + B x 11 +
Fx1
MAXIMUM FLUE VERTICAL
WITH 2 x 45° BENDS
Ø100 - 4400mm
(including terminal)
B x 5 + D x 2 + E x 1
Ø125 - 13000mm
(including terminal)
B x 13 + D X 2 + E x 1
Ø100 - 2400mm
(including terminal)
B x 4 + C x 2 + E x 1
Ø125 - 11000mm
(including terminal)
B x 13 + C x 2 + E x 1
VERTICAL FLUE WITH
2 x 90° BENDS
A
A
B
A
B
F
C
A
B
C
F
B
C
A
F
B
C
A
E
B
D
E
B
C
MAXIMUM FLUE VERTICAL
START + 3 BENDS

IIMPORTANT: All the previous Pre-Installation sections must be read
and requirements met before starting boiler or flue installation.
E
F
A
B
CC
D
G
UNPACKING WALL FRAME AND
ANCILLARY ITEMS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 107 336b (11/05)
18
INSTALLATION
1
2
3
A - Straps
B - Outer carton
C - Installer pack
D - Bottom panel
E - Wall mounting frame
F - Wall template
G - Inner packaging
IMPORTANT HANDLING INSTRUCTIONS
• It is advised that two people are used to carry
the carton from the van to the point of delivery.
• Once the carton has been delivered, the outer
carton is removed first. Care should be taken
when releasing the straps. If a sharp implement
is used make sure the outer carton is not
pierced and that the implement is used in such
a way so that it may not cause personal injury.
All sharp objects must be covered or the blade
retracted after use and put away in a safe
place. The wall mounting frame, Installer
pack, template and bottom panel are now
removed. Care should be taken when lifting the
boiler from the base and the proper technique
for safe lifting of any heavy object should be
strictly observed.
Additional requirements for roof space
installation:
• The boiler should be first unpacked before
ascending ladder to loft space.
• Two sets of steps should be used.
• Two people should share the lifting of the
boiler up to the loft hatch, where the boiler is
entered into the loft space tilted and slid on its
back into the loft.
Once the appliance is removed from its
packaging check the contents against the
packing list.
Before installing appliance ensure system has
been cleaned as explained on page 8.
1. Remove straps (A) and open the top of the
boiler packaging.
2. Remove template (F) and wall mounting
frame (E) from the packaging.
3. Remove boiler bottom panel (D) and
installer pack (C).
UNPACKING WALL FRAME AND
ANCILLARY ITEMS
LIFTING AND CARRYING PRECAUTIONS:
• Lift only a manageable weight, or ask for
help.
• When lifting or putting things down, bend
the knees, and keep the back straight
and feet apart.
• Do not lift and twist at the same time.
• Lift and carry objects close to the body

WALL MOUNTING PLATE FLUE OPENING INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 107 336b (11/05)
19
INSTALLATIONCOMMISSIONING
SAFETY:
All relevant safety precautions must be undertaken.
Protective clothing, footwear, gloves and safety
goggles must be worn as appropriate.
FIXING THE MOUNTING FRAME:
• The boiler template shows the relative
positions of the flue and the top and bottom
fixing of the mounting frame.
Fix the template to the wall in the desired
position (A).
Drill 4 holes for the wall mounting frame
through the template (2).
NOTE: The template has been sized to allow for
minimum clearances of 5mm sides, 200mm
base and 30mm above a Ø100mm flue elbow.
REAR FLUE OUTLET
• The drawing (B) opposite shows the boiler
template with the flue centre lines of both the
100mm and 125mm flue systems.
Mark centreline of flue to be used (1); the
external diameter of the hole can also be
marked if required.
• If a Ø100mm diameter flue is to be used,
a125mm diameter hole is required. However, if
using the weather sealing collar by pushing it
through from inside the property, then a
150mm diameter hole is required to
accommodate this.
• The terminal section of the 100mm flue has an
inbuilt 3° angle.
If extensions are to be added then the complete
flue must rise at an angle of 3°.
• The 125mm Ø flue system will require the flue
to rise at an angle of 3°.
Drill hole using a core drill or similar.
SIDE OUTLET:
Mark from the centre line of the wall template
to the wall which the flue will pass through (3).
Allow for a rise of 52mm per metre length of
flue, to give a 3° angle.
Clear any debris from the site.
• A pre-filling kit 7 716 192 282 is available for
installations where the boiler will not be fitted
immediately to the heating system. This allows
the heating system and mains water connec-
tions to be filled and checked prior to boiler
installation.
This kit can be used in conjunction with the
optional filling loop 7 716 192 281(not sup-
plied with the boiler).
CAUTION: Ensure there are no pipes,
electric cables, damp proof courses or
other hazards before drilling.
WALL MOUNTING TEMPLATE
FLUE OPENING
189mm
2
A
B
X 4
X 4
USE APPROPRIATE
FIXINGS FOR
WEIGHT AND
WALL TYPE