Worcester GREENSTAR 24i junior User manual

THE APPLIANCE IS FOR USE WITH
NATURAL GAS OR L.P.G. (Cat II 2H3P TYPE C13, C33 & C53)
NATURAL GAS:
24i junior GC NUMBER 47-311-86
28i junior GC NUMBER 47-311-87
LIQUID PETROLEUM GAS:
24i junior GC NUMBER 47-311-90
28i junior GC NUMBER 47-311-91
UK/IE
INSTRUCTION MANUAL
INSTALLATION, COMMISSIONING & SERVICING
WALL HUNG RSF GAS FIRED CONDENSING COMBINATION BOILER
GREENSTAR 24i jjuunniioorr/ 28i jjuunniioorr
FOR SEALED CENTRAL HEATING SYSTEMS AND MAINS FED
DOMESTIC HOT WATER

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SYMBOLS USED IN THIS MANUAL:
Central heating
Domestic hot water
Cold water main supply
Electricity supply
Gas supply
Hot water storage cylinder
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/IE ONLY AND MUST BE FOLLOWED EXCEPT FOR
ANY STATUTORY OBLIGATION.
THIS APPLIANCE MUST BE INSTALLED BY A CORGI REGISTERED, 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 INSTALLATION OR SERVIC-
ING. 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
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
8 716 115 166a (06/2008)
2
WATER TREATMENT:
FERNOX 01799 550811
www.fernox.com
SENTINEL 0800 389 4670
www.sentinel-solutions.net
FLUE TERMINAL GUARDS:
TOWER FLUE COMPONENTS LTD.
Vale Rise, Tonbridge TN9 1TB
01732 351555

SAFETY & REGULATIONS
INSTALLATION AND SERVICING INSTRUCTIONS 2
SAFETY PRECAUTIONS & SYMBOLS 4
INSTALLATION REGULATIONS 4
APPLIANCE INFORMATION
GENERAL INFORMATION 5
TECHNICAL DATA 6
LAYOUT & COMPONENTS 7
PRE-INSTALLATION
CLEANING PRIMARY SYSTEMS 9
MAINS SUPPLY 10
WATER SYSTEMS & PIPEWORK 11
CONDENSATE PIPEWORK 12
PRESSURE RELIEF PIPEWORK 13
BOILER LOCATION & CLEARANCES 14
PLUMBING MANIFOLD 16
FLUE OPTIONS 17
FLUE TERMINAL POSITIONS 18
INSTALLATION
UNPACKING THE WALL FRAME 20
WALL MOUNTING TEMPLATE / FLUE OPENING 21
UNPACKING THE APPLIANCE 22
BOILER CONNECTIONS 23
FLUE INSTALLATION 25
CONDENSATE CONNECTIONS 28
ELECTRICS 29
POSITION OF WIRED COMPONENTS 30
COMMISSIONING
PRE-COMMISSIONING CHECKS 31
FILLING THE SYSTEM 32
STARTING THE APPLIANCE 33
WATER TREATMENT 34
COMMISSIONING 35
FINISHING COMMISSIONING 36
SERVICING & SPARES
INSPECTION AND SERVICE 37
REPLACEMENT OF PARTS 43
SETTING THE AIR/GAS RATIO 55
SHORT PARTS LIST 56
CONVERSION KITS
L.P.G. CONVERSION 57
FAULT FINDING & DIAGNOSIS
FAULT FINDING 58
CENTRAL HEATING FUNCTION 59
PREHEAT AND DHW FUNCTION 60
PROTECTION FUNCTION 61
BENCHMARK CHECKLIST
SERVICE INTERVAL RECORD SHEET
CONTENTS
CONTENTS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
SAFETY &
REGULATIONS
APPLIANCE
INFORMATION
PRE -
INSTALLATION
INSTALLATIONCOMMISSIONING
SERVICING
& SPARES
CONVERSION
KITS
FAULT FINDING
& DIAGRAMS

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 Worcester, Bosch Group, at the back of this manual,
for the installer to complete. The checklist will include 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, 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 will 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 other CORGI registered personnel) using approved
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.
Current Gas Safety (Installation & Use)
Regulations:
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 sec -
ondary domestic water system must be approved
by WRAS.
IMPORTANT: ARTIFICIALLY SOFTENED
WATER MUST NOT BE USED TO FILL THE
CENTRAL HEATING SYSTEM.
spares,
SAFETY PRECAUTIONS
& INSTALLATION REGULATIONS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
4
SAFETY &
REGULATIONS

GENERAL INFORMATION
700mm*
400mm
A
330mm
GENERAL INFORMATION
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
5
APPLIANCE
INFORMATION
B
C
D
(When fitted to wall frame)
Depth to wall
Check List
Hardware/Literature pack
Item Qty.
Greenstar 24i Junior/28i Junior Installation/Servicing Instructions.....1
Users Instructions ..........................................................................................1
Consumer Guarantee Card .........................................................................1
Syphon assembly............................................................................................1
Installation instructions...........................................................................1
Sealing Pack...................................................................................................1
Compression Nut 22mm ....................................................................... 3
Compression Ring 22mm ..................................................................... 3
Compression Nut 15mm ....................................................................... 3
Compression Ring 15mm ..................................................................... 3
Fibre Washer 18.6 x 13.5 x 1.5 ............................................................ 2
Fibre Washer 23.9 x 17.2 x 1.5............................................................. 2
Bonded Washer 3/4 ...............................................................................1
Syphon assembly............................................................................................1
Installation instructions..................................................................................1
Irish Guidelines Leaflet .................................................................................1
Warranty Return Envelope ...........................................................................1
ESTANDARD PACKAGE:
A - Wall hung gas fired condensing combi boiler
for central heating and domestic hot water
B - Boiler support frame
C -Hardware literature pack (see checklist)
D - Bottom Panel
E - Fascia panel
F - Syphon assembly
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 & temperature control
•Plate type DHW heat exchanger
F
*710mm to top case front

TECHNICAL DATA INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
6
TECHNICAL DATA
APPLIANCE
INFORMATION
DESCRIPTION NATURAL GAS L.P.G.
UNIT 24 iJunior 28 iJunior 24 iJunior 28 iJunior
Domestic Hot Water
Min. heat input KW 7. 3 8 7. 3 8 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 (after 30 mins) %9.8 9.8 11.0 11.0
CO2level at min. rated heat output (after 30 mins) %9.2 9.2 10.5 10.5
NOx - class 5 5 5 5
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 W140 140 140 140
General Data
SEDBUK band A A A A
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
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

LAYOUT & COMPONENTS
LAYOUT & COMPONENTS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
7
APPLIANCE
INFORMATION
The diagram opposite shows the controls in the
servicing position and excludes the outer case.
1 AIR / GAS MANIFOLD
2 SENSOR - BOILER FLOW
3 IGNITION AND FLAME SENSE ELECTRODES
4 OVERHEAT THERMOSTAT
5 RETAINING BRACKET
6 EXPANSION VESSEL
7 REMOVABLE PANEL FOR SERVICING
8 SILICONE TUBE (HEAT EXCHANGER
AIR VENT)
9 SECURING NUT, AIR / GAS MANIFOLD
CLAMP
10 FAN DRIP GUARD
11 HEAT EXCHANGER
12 WALL MOUNTING FRAME
13 FLUE OVERHEAT THERMOSTAT
14 SYSTEM PRESSURE GAUGE
15 PUMP
16 DRAIN POINT
17 CH RETURN
18 CONTROL PANEL IN SERVICE POSITION
19 MAINS COLD WATER IN
20 COVER FOR EXTERNAL WIRING
CONNECTIONS
21 GAS INLET CONNECTION 22mm
COMPRESSION
22 DHW OUT
23 ACCESS COVER FOR TRANSFORMER
& PCB
24 CH FLOW
25 SYPHON OUTLET CONNECTION
(22mm PLASTIC PIPE)
2 6 P LATE TO P LAT E D HW H EAT
EXCHANGER
27 ACCESS POINT FOR CLEANING
HEAT EXCHANGER/SUMP
28 GAS VALVE
29 FAN
30 MANUAL VENT POINT
31 FAN PRESSURE TEST POINT
32 FLUE AIR PRESSURE SWITCH
CONNECTION (BLANKED OFF ON THIS
APPLIANCE)

LAYOUT & COMPONENTS
LAYOUT & COMPONENTS INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
8
APPLIANCE
INFORMATION
14 SYSTEM PRESSURE GAUGE
15 SYSTEM PUMP
26 P LATE TO PL ATE DH W HEAT
EXCHANGER
33 FLOW TURBINE
34 COMPACT HYDRAULIC MOUNTING
SCREW (2) TO BOILER
35 PRESSURE RELIEF VALVE
36 DIVERTER VALVE
37 CH RETURN CONNECTION TO SERVICE
VALVE
38 DRAIN TAP
39 COLD WATER IN CONNECTION
40 INTERNAL BYPASS WITHIN PLASTIC
MOULDING
41 DHW OUT CONNECTION
42 CH FLOW CONNECTION TO SERVICE
VALVE
43 DHW SENSOR
44 FLOW CONNECTION FROM BOILER
HEAT EXCHANGER
45 AUTO AIR VENT
46 UNUSED PORT
47 FAULT RESET BUTTON
48 ECO BUTTON
49 MAINS ON/OFF INDICATOR/
DIAGNOSTIC LIGHT (BLUE)
50 CH TEMPERATURE CONTROL
51 POSITION FOR OPTIONAL
PROGRAMMER
52 SERVICE MODE BUTTON
53 BURNER ON INDICATOR LIGHT (GREEN)
54 MASTER SWITCH ON/OFF

CLEANING PRIMARY SYSTEMS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
9
PRE -
INSTALLATION
CLEANING PRIMARY SYSTEMS
BEFORE CLEANING THE SYSTEM:
ENSURE THE SYSTEM AND PIPEWORK
IS IN GOOD WORKING ORDER
WHERE POSSIBLE KEEP THE EXISTING
BOILER/CIRCULATING PUMP IN PLACE
WHEN FLUSHING THE SYSTEM.
FOLLOW GUIDANCE OF BS7593:
TREATMENT OF WATER IN DOMESTIC
HOT WATER CENTRAL HEATING AND
ALSO FLUSHING GUIDELINES SET OUT
BELOW.
CLEANING THE PRIMARY SYSTEM:
IMPORTANT: ARTIFICIALLY SOFTENED
WATER MUST NOT BE USED TO FILL THE
CENTRAL HEATING SYSTEM
• Fill the system with cold water and
check for leaks.
• Open all drain cocks and drain the
system.
• 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.
• Run the boiler/system at normal operating
temperature as directed by the manufacturer
of the flushing agent.
• Drain and thoroughly flush the system to
remove the flushing agent and debris.
• It may be necessary to use a power flushing
machine to aid the cleansing procedure in
some circumstances
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.

MAINS SUPPLY INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
10
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
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.
• This appliance must not be connected to a
three phase supply.
• IPX4D.
NOTE: this is reduced to IP20 if the
following mechanical timers are fitted:
7 716 192 036 or 7 716 192 037.
• Wiring must comply with latest 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

WATER SYSTEMS & PIPEWORK
PLASTIC PIPEWORK:
• Any plastic pipework must have a polymeric
barrier with 600mm (minimum) length of
copper 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.
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-syphon 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.
IMPORTANT: ARTIFICIALLY SOFTENED
WATER MUST NOT BE USED TO FILL THE
CENTRAL HEATING SYSTEM
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.
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
8 716 115 166a (06/2008)
11
PRE -
INSTALLATION

CONDENSATE PIPEWORK INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
12
PRE -
INSTALLATION
CONDENSATE PIPEWORK
Fitting an external air break
Use the situation opposite when a rain water
down pipe is used to dispose of condensate
and the down pipe goes directly into an
existing sewer that carries both rainwater
and foul water.
An air break must be installed in the 32/43
mm pipework, between the boiler
condensate outlet and the drainpipe, outside
the property, to avoid flooding during
adverse weather conditions.
CONDENSATE PIPEWORK:
• The condensate pipe must be a minimum of
22 mm Ø plastic pipe.
• The condensate pipework must fall at
least 50 mm per metre towards the outlet
and should take the shortest practicable
route.
• The pipework must follow one of the options
shown opposite or discharge directly into a
vent stack min. 450 mm above pipe invert or
into a gully below ground but above the water
level.
• Wherever possible the condensate
discharge pipe work should be routed and
terminated internally. Should this not be
possible, and the only available route is
external, the following conditions should be
observed:
External pipe work
- Pipe work length should be kept to a
minimum and the route as vertical as
possible.
- Where pipe work is subjected to
extreme cold or wind chill, a weather
proof insulation should be used.
Alternatively the condensate pipework
could be increased to a minimum
diameter of 32 mm without the
requirement to insulate.he pipe run
IMPORTANT:
• Ensure there are no
blockages in the pipe run
• Care should be taken when
siting a soak-away to avoid
obstructing existing services
• Condensate waste must not
be terminated into a septic
tank or cesspit
Condensate soakaway
The condensate drainage pipe may be run
above or below the ground to the soakaway.
The example shown opposite runs above
ground level.
The soakaway must use a 100mm diameter
plastic tube with two rows of three 12 mm
holes on 25 mm centres and 50 mm from
the bottom of the tube. The holes must face
away from the house.
The tube must be surrounded by at least
100 mm of limestone chippings to a depth
of 400mm.

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
8 716 115 166a (06/2008)
13
PRE -
INSTALLATION
M
N
O
L

1450mm
930mm 410mm
+ 30mm
above elbow
5mm
5mm
20mm
to removable door
200mm
600mm
front clearance
for service
This boiler is only suitable for installing internally
within a property at a suitable location onto a
fixed, rigid surface at least the same size as the
boiler and capable of supporting 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.
*NOTE: These are the combined top & bottom
clearances excluding the appliance.
**NOTE: These are the combined left & right
clearances excluding the appliance.
BOILER LOCATION &
CLEARANCES
SERVICING CLEARANCES
VENTED COMPARTMENT
Using 100mm flue kit
1080mm
Using 125mm flue kit
- 1110mm
VENTILATION FREE COMPARTMENTS
INSTALLATION CLEARANCES
Ventilation Free Compartment 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
8 716 115 166a (06/2008)
14
PRE -
INSTALLATION
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

BOILER LOCATION & CLEARANCES
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
15
PRE -
INSTALLATION
11
2
2
11
2
BATHROOMS:
A boiler fitted with a non-mechanical timer or
with no timer can be installed in zone 2 or out-
side the shaded area .
A boiler with a mechanical timer, RF mechanical
timer or text display with room thermostat must
only be installed outside the shaded area.
Additional RCD (Residual Current Device) pro-
tection may be required.
Refer to the latest IEE wiring regulations.
BOILER LOCATION &
CLEARANCES
2

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.
*
PLUMBING MANIFOLD INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
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PRE -
INSTALLATION
Further guidance on pipe routing can be
found printed on the boiler template
(supplied with the boiler).
CH Return 22mm
CH Flow 22mm
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

PRE -
INSTALLATION
FLUE OPTIONS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
17
Maximum telescopic flue length
100mmØ 125mmØ
24 i jun. 570mm 1,070m m
28 i jun. 570mm 1,070m m
Maximum total flue length
100mmØ 125mmØ
24 i jun. 4,600mm 13,000mm
28 i jun. 4,600mm 13,000mm
Maximum total flue length
100mmØ 125mmØ
24 i jun. 4,600mm 13,000mm
28 i jun. 4,600mm 13,000mm
Maximum total flue length
100mmØ 125mmØ
24 i jun. 2,600mm 11,000mm
28 i jun. 2,600mm 11,000mm
Maximum total flue length
100mmØ 125mmØ
24 i jun. 2,600mm 11,000mm
28 i jun. 2,600mm 11,000mm
Maximum total flue length
100mm‚Ø 125mmØ
24 i jun. N/A 9,000mm
28 i jun. N/A 9,000mm
Maximum total flue length
100mmØ 125mmØ
24 i jun. 6,400mm 15,000mm
28 i jun. 6,400mm 15,000mm
Maximum total flue length
100mm‚Ø 125mmØ
24 i jun. 4,400mm 13,000mm
28 i jun. 4,400mm 13,000mm
Maximum total flue length
100mmØ 125mmØ
24 i jun. 2,400mm 11,000mm
28 i jun. 2,400mm 11,000mm
Telescopic horizontal flue assembly
Horizontal flue extension
High level horizontal flue
Horizontal flue with 2x90° bends
High level horizontal flue with 2x90° bends
High level horizontal flue with 3x90° bends
Vertical balanced flue assembly
Vertical balanced flue system with 2x45° bends
Vertical balanced flue with 2x90° bends
FLUE OPTIONS
The Greenstar series has the option of two horizontal RSF (60/100 telescopic and
80/125) flue systems and two vertical RSF (60/100 or 80/125) flue systems:
The systems have different maximum flue lengths
This page shows various fluing options with the straight flue lengths required to achieve
the maximum flue length. Note that:
• each 90° bend used is equivalent to 2 metres of straight flue
• each 45° bend used is equivalent to 1 metre of straight flue
NOTE: Plume management kits are available for the 60/100 horizontal flue option.
Refer to the manual supplied with the Plume management kits for complete
installation instructions

FLUE TERMINAL POSITIONS INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
18
PRE -
INSTALLATION
• 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. Where this could be a nuisance,
for example, near security lighting, an alter-
nate position should be found.
• 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: Part 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 (mini-
mum 50 mm) around the flue and fixed to
the wall with plated screws. See Contact
Information (inside front cover).

INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 115 166a (06/2008)
19
FLUE TERMINAL POSITIONS
FLUE TERMINAL POSITIONS
PRE -
INSTALLATION