Worcester 41-311-67 User guide

UK/IE
INSTALLATION, COMMISSIONING AND SERVICING
INSTRUCTIONS
WALL HUNG RSF GAS FIRED CONDENSING BOILER
GREENSTAR i SYSTEM
6720643356-00 1Wo
FOR SEALED CENTRAL HEATING SYSTEMS AND INDIRECTLY
FED DOMESTIC HOT WATER
6720644743a (2010/10)
The appliance is for use with Natural Gas or
L.P.G. (Cat II 2H3P type C13, C33 & C53)
Model GC Number
Natural Gas 12i System 41-311-67
15i System 41-311-84
18i System 41-311-86
24i System 41-311-68
Liquid Petroleum Gas 12i System 41-311-69
15i System 41-311-85
18i System 41-311-87
24i System 41-311-70

CONTENTS
6 720 644 743a (2010/10)
2
CONTENTS
1 KEY TO SYMBOLS AND SAFETY PRECAUTIONS 3
1.1 Explanation of symbols . . . . . . . . . . . . . . 3
1.2 Safety precautions . . . . . . . . . . . . . . . . . 4
2 APPLIANCE INFORMATION . . . . . . . . . . . . . . . . 6
2.1 Appliance . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Technical data . . . . . . . . . . . . . . . . . . . . . 7
2.3 Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3 PRE-INSTALLATION . . . . . . . . . . . . . . . . . . . . . 11
3.1 Cleaning primary systems . . . . . . . . . . . 11
3.2 Mains supply . . . . . . . . . . . . . . . . . . . . . 12
3.2.1 Electrical supply . . . . . . . . . . . . . . . . . . 12
3.2.2 Equipotential (earth) bonding . . . . . . . . 12
3.2.3 Gas supply . . . . . . . . . . . . . . . . . . . . . . 12
3.3 Water system and pipe work . . . . . . . . 13
3.4 Condensate pipe work . . . . . . . . . . . . . 15
3.4.1 Internal connections . . . . . . . . . . . . . . . 15
3.4.2 External connections . . . . . . . . . . . . . . . 16
3.5 Pressure relief pipe work . . . . . . . . . . . 18
3.6 Boiler location and clearances . . . . . . . 19
3.6.1 Installation . . . . . . . . . . . . . . . . . . . . . . 19
3.6.2 Servicing clearances -
Ventilated compartment . . . . . . . . . . . . 19
3.6.3 Compartments . . . . . . . . . . . . . . . . . . . 19
3.6.4 Bathrooms . . . . . . . . . . . . . . . . . . . . . . . 19
3.6.5 Boiler clearances -
Unventilated compartments . . . . . . . . . . 20
3.6.6 Installation clearances -
Unventilated compartments . . . . . . . . . . 20
3.7 Plumbing manifold . . . . . . . . . . . . . . . . 21
3.7.1 Connections . . . . . . . . . . . . . . . . . . . . . 21
3.8 Flue options . . . . . . . . . . . . . . . . . . . . . 22
3.9 Flue terminal positions . . . . . . . . . . . . . 24
3.10 Plume management terminal positions . 25
4 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.1 Unpacking the wall frame and ancillary
items . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.2 Wall mounting template & flue opening 27
4.3 Unpacking the appliance . . . . . . . . . . . . 28
4.4 Boiler connections . . . . . . . . . . . . . . . . 29
4.5 Flue installation . . . . . . . . . . . . . . . . . . . 31
4.5.1 Measuring the flue (standard flue): . . . 31
4.5.2 Reducing the telescopic flue length: . . . 31
4.5.3 Installing the telescopic flue: . . . . . . . . 32
4.5.4 Flue terminal plume re-direction . . . . . . 33
4.6 Condensate connection . . . . . . . . . . . . 34
4.7 Electrical . . . . . . . . . . . . . . . . . . . . . . . . 35
5 COMMISSIONING . . . . . . . . . . . . . . . . . . . . . . . 37
5.1 Pre-Commissioning checks . . . . . . . . . . 37
5.2 Filling the system . . . . . . . . . . . . . . . . . 38
5.3 Water treatment . . . . . . . . . . . . . . . . . . 38
5.4 Starting the appliance . . . . . . . . . . . . . . 39
5.5 Commissioning . . . . . . . . . . . . . . . . . . . 40
5.5.1 Checking the gas inlet pressure . . . . . . 40
5.5.2 Checking the gas rate . . . . . . . . . . . . . . 41
5.5.3 Domestic hot water: . . . . . . . . . . . . . . . 41
5.6 Finishing commissioning . . . . . . . . . . . . 42
5.6.1 Replace outer casing: . . . . . . . . . . . . . . 42
5.6.2 Fitting fascia flap . . . . . . . . . . . . . . . . . . 42
5.6.3 Installing bottom panel . . . . . . . . . . . . . 42
5.6.4 Handover . . . . . . . . . . . . . . . . . . . . . . . . 42
6 SERVICE AND SPARES . . . . . . . . . . . . . . . . . . . 43
6.1 Inspection and service . . . . . . . . . . . . . . 43
6.2 Check the gas inlet pressure . . . . . . . . . 44
6.3 Checking flue integrity . . . . . . . . . . . . . . 44
6.4 Fan pressure test . . . . . . . . . . . . . . . . . . 45
6.5 Flue gas analysis . . . . . . . . . . . . . . . . . . 45
6.6 Setting the air/gas ratio . . . . . . . . . . . . . 47
6.6.1 Setting the CO/CO2 . . . . . . . . . . . . . . . 47
6.7 Cleaning the heat exchanger . . . . . . . . . 48
6.8 Replacement of parts . . . . . . . . . . . . . . 51
6.8.1 Removing outer case . . . . . . . . . . . . . . . 51
6.8.2 Primary sensor . . . . . . . . . . . . . . . . . . . . 51
6.8.3 Overheat thermostat . . . . . . . . . . . . . . . 51
6.8.4 Flue overheat thermostat . . . . . . . . . . . 52
6.8.5 Moving controls to service position . . . . 52
6.8.6 Gas valve . . . . . . . . . . . . . . . . . . . . . . . . 53
6.8.7 Air/gas manifold and fan assembly . . . . 53
6.8.8 Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
6.8.9 Electrode assembly and burner . . . . . . . 55
6.8.10 Heat exchanger . . . . . . . . . . . . . . . . . . . 55
6.8.11 Access to boiler control components . . 57
6.8.12 PCB Fuse . . . . . . . . . . . . . . . . . . . . . . . . 57
6.8.13 Transformer/PCB . . . . . . . . . . . . . . . . . . 57
6.8.14 Replacing controls . . . . . . . . . . . . . . . . . 58
6.8.15 Syphon removal . . . . . . . . . . . . . . . . . . . 59
6.8.16 Diverter valve motor (If fitted) . . . . . . . . 59
6.8.17 Diverter valve (If fitted) . . . . . . . . . . . . . 59
6.8.18 Auto air vent . . . . . . . . . . . . . . . . . . . . . 60
6.8.19 Pump head . . . . . . . . . . . . . . . . . . . . . . . 60
6.8.20 Drain tap . . . . . . . . . . . . . . . . . . . . . . . . 60
6.8.21 Pressure gauge . . . . . . . . . . . . . . . . . . . 61
6.8.22 Hydraulic block removal . . . . . . . . . . . . 61
6.8.23 CH Pressure relief valve . . . . . . . . . . . . . 62
6.8.24 Bypass valve . . . . . . . . . . . . . . . . . . . . . 62
6.8.25 Expansion vessel . . . . . . . . . . . . . . . . . . 62
6.9 Short parts list . . . . . . . . . . . . . . . . . . . . 64
7 FAULT FINDING AND DIAGNOSIS . . . . . . . . . . 65
7.1 Fault finding . . . . . . . . . . . . . . . . . . . . . . 65
7.1.1 Circuit diagram . . . . . . . . . . . . . . . . . . . 67
7.2 Central heating function . . . . . . . . . . . . 68
7.3 Protection function . . . . . . . . . . . . . . . . 69

KEY TO SYMBOLS AND SAFETY PRECAUTIONS
6 720 644 743a (2010/10) 3
1 KEY TO SYMBOLS AND SAFETY PRECAUTIONS
1.1 EXPLANATION OF SYMBOLS
WARNING SYMBOLS
Signal words indicate the seriousness of the hazard in
terms of the consequences of not following the safety
instructions.
•NOTICE indicates possible damage to property or
equipment, but where there is no risk of injury.
•CAUTION indicates possible injury.
•WARNING indicates possible severe injury.
•DANGER indicates possible risk to life.
IMPORTANT INFORMATION
ADDITIONAL SYMBOLS
SYMBOLS USED IN THIS MANUAL
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 GAS SAFE
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
SERVICING.
THE BENCHMARK CHECKLIST CAN BE FOUND IN THE
BACK PAGES OF THE INSTALLATION MANUAL.
ABBREVIATIONS USED IN THIS MANUAL:
Safety instructions in this document are
framed and identified by a warning triangle
which is printed on a grey background.
Electrical hazards are identified by a
lightning symbol surrounded by a warning
triangle.
Notes contain important information in
cases where there is no risk of personal
injury or material losses and are identified
by the symbol shown on the left. They are
bordered by horizontal lines above and
below the text.
Symbol Meaning
Ba step in an action sequence
Æa reference to a related part in the
document or to other related documents
•a list entry
–a list entry (second level)
Tab. 1 Symbols
Domestic Hot Water
Central Heating
Hot Water Storage Cylinder
Domestic Cold Water Supply
Electrical Supply
Gas Supply
Tab. 2 Commonly used symbols
ØDiameter
NG Natural Gas
LPG Liquid Petroleum Gas
CH Central Heating
DHW Domestic Hot Water
PRV Pressure Relief Valve
NTC Negative Temperature Coefficient (sensor)
IP Ingress Protection
RCD Residual Current Device
TRV Thermostatic Radiator Valve
WRAS Water Regulations Advisory Scheme
SEDBUK Seasonal Efficiency of Domestic Boilers in
the United Kingdom
Tab. 3 Abbreviations

KEY TO SYMBOLS AND SAFETY PRECAUTIONS
6 720 644 743a (2010/10)
4
1.2 SAFETY PRECAUTIONS
IF YOU SMELL GAS:
BCALL NATIONAL GAS EMERGENCY SERVICE ON
0800 111 999
BLPG BOILERS CALL THE SUPPLIER‘S NUMBER ON
THE SIDE OF THE LPG TANK
BTURN OFF THE ECV (EMERGENCY CONTROL VALVE)
AT THE METER/REGULATOR
BDO NOT TURN ELECTRICAL SWITCHES ON OR OFF
BDO NOT STRIKE MATCHES OR SMOKE
BPUT OUT NAKED FLAMES
BOPEN DOORS AND WINDOWS
BKEEP PEOPLE AWAY FROM THE AFFECTED AREA
BOILER OPERATION:
This boiler must only be operated by a responsible
adult who has been instructed in, understands, and is
aware of the boiler's operating conditions and effects.
Benchmark places responsibilities on both
manufacturers and installers. The purpose is to ensure
that customers are provided with the correct equipment
for their needs, that it is installed, commissioned and
serviced in accordance with the manufacturer's
instructions by competent persons and that it meets the
requirements of the appropriate Building Regulations.
The Benchmark Checklist can be used to demonstrate
compliance with Building Regulations and should be
provided to the customer for future reference.
Installers are required to carry out installation,
commissioning and servicing work in accordance with
the Benchmark Code of Practice which is available from
the Heating and Hotwater Industry Council who manage
and promote the scheme.
Visit centralheating.co.uk for more information.
HEALTH AND 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).
COMBUSTION 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 AND 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 Gas Safe registered engineer.
Approved spares must be used 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.
INSTALLATION REGULATIONS
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.

KEY TO SYMBOLS AND SAFETY PRECAUTIONS
6 720 644 743a (2010/10) 5
British Standards:
Where no specific instruction is given, reference should
be made to the relevant British Standard codes of
Practice.
BS7074:1 Code of practice for domestic and hot water
supply
BS6891 Installation of low pressure gas pipe work up
to 28mm (R1)
BS5546 Installation of gas hot water supplies for
domestic purposes
EN12828 Central heating for domestic premises
BS5440:1 Flues and ventilation for gas appliances of
rated heating not exceeding 70kW (net) :
Flues
BS5440:2 Flues and ventilation for gas appliances of
rated heating not exceeding 70kW (net) : Air
Supply
BS7593 Treatment of water in domestic hot water
central heating systems
BS6798 Installation of gas fired boilers of rated input
up to 70kW (net)
Irish Standards
The relevant Irish standards should be followed,
including:
•ECTI National rules for electrical installations
•IS 813:2002 for Domestic Gas Installations.
LPG Installations
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 building:
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.
BOILER FEATURES AND CHECKLIST
•Pre-wired and pre-plumbed
•Galvanised steel inner frame
•Digital control system
•FX Intelligent controls
•Low NOx option
•Automatic ignition
•Direct burner ignition electrodes
•Built-in frost protection
•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 sensor
•Condensate syphonic trap
•Temperature control
CHECK LIST
- HARDWARE LITERATURE PACK: Qty.
Greenstar 12i/15i/18i & 24i System
Installation, Commissioning and Servicing
Instructions
1
Users Instructions 1
Consumer Guarantee Card 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“ for gas 1
Syphon assembly 1
- Installation instructions 1
Warranty Return Envelope 1
Tab. 4 Hardware lit pack - checklist

APPLIANCE INFORMATION
6 720 644 743a (2010/10)
6
2APPLIANCEINFORMATION
2.1 APPLIANCE
Fig. 1
2
43
5
* 710mm to top of case front
1
700mm*
400mm
330mm Depth to wall
(When tted to wall frame)
6
6720643895-01.1Wo
STANDARD PACKAGE:
1 Wall hung gas fired condensing system boiler
for central heating and hot water
2 Wall mounting frame
3 Hardware literature pack (see checklist)
4 Bottom Panel
5 Fascia panel
6 Syphon assembly
Tab. 5

APPLIANCE INFORMATION
6 720 644 743a (2010/10) 7
2.2 TECHNICAL DATA
DESCRIPTION NATURAL GAS LPG
UNIT 12i 15i 18i 24i 12i 15i 18i 24i
Gas flow rate - Max. 10 minutes from lighting
Natural Gas G20 m³/h 1.33 1.63 1.96 2.67 ----
Propane Gas (LPG) kg/h ----0.96 1.20 1.44 1.91
Central Heating
Maximum rated heat input (net) kW 12.32 15.40 18.48 24.62 12.32 15.40 18.48 24.62
Minimum heat input kW 3.45 4.62 5.54 7.38 5.95 5.95 9.64 9.64
Max. rated heat output 40/30 °C kW 12.85 16.06 19.28 25.67 12.85 16.06 19.28 25.67
Max. rated heat output 50/30 °C kW 12.74 15.92 19.11 25.45 12.74 15.92 19.11 25.45
Max. rated heat output 80/60 °C kW 12 15 18 24 12 15 18 24
Max. flow temperature °C 82 82 82 82 82 82 82 82
Max. flow temperature to cylinder (with integral
optional diverter valve)
°C 75 75 75 75 75 75 75 75
Max. permissible operating pressure bar 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5
Available pump head at 21 °C system temp. rise m 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0
Flue
Flue gas temp. 80/60 °C, rated/min. load °C 62/56 66/58 70/60 78/63 62/57 66/59 71/61 79/64
Flue gas temp. 40/30 °C, rated/min. load °C 41/33 44/33 48/34 54/35 43/35 46/36 49/37 55/38
CO2level at max. rated heat output (after 30 min) % 9.65 9.8 9.8 9.8 11.0 11.0 11.0 11.0
CO2level at min. rated heat output (after 30 min) % 8.65 9.2 9.2 9.2 10.5 10.5 10.5 10.5
NOx class 55455545
NOx rating mg/kWh 39 60 84 66 44 60 84 66
Condensate
Maximum condensate rate l/h 0.93 1.2 1.5 2.0 0.7 0.9 1.2 1.5
pH value, approx. 4.8 4.8 4.8 4.8 4.8 4.8 4.8 4.8
Electrical
Electrical power supply voltage a.c. V 230 230 230 230 230 230 230 230
Frequency Hz 50 50 50 50 50 50 50 50
Maximum power consumption W 140 140 140 140 140 140 140 140
General data
SEDBUK band AAAAAAAA
Appliance protection rating IP X4D X4D X4D X4D X4D X4D X4D X4D
Permissible ambient temperatures °C 0 - 50 0 - 50 0 - 50 0 - 50 0 - 50 0 - 50 0 - 50 0 - 50
Nominal capacity of appliance litre 3.9 3.9 3.9 3.9 3.9 3.9 3.9 3.9
Noise output level (Max central heating) dBA 42 42 42 42 42 42 42 42
Packaged boiler weight kg 41 41 41 41 41 41 41 41
Total boiler weight kg 37.5 37.5 37.5 37.5 37.5 37.5 37.5 37.5
Lift weight kg 27.1 27.1 27.1 27.1 27.1 27.1 27.1 27.1
SEDBUK % 90.1 90.1 90.1 90.1 91.4 91.4 91.4 92.0
Tab. 6 Technical data i System

APPLIANCE INFORMATION
6 720 644 743a (2010/10)
8
2.3 LAYOUT
Fig. 2 Main boiler components
6720644743-02.1Wo
12
31
30
29
28
27
26
10
14
12
11
13
15
16
25
23
24
22
21 20 19 18 17
34
5
6
7
8
9

APPLIANCE INFORMATION
6 720 644 743a (2010/10) 9
Fig. 3 Hydraulic block components
1ExpansionVessel 23 Hydraulic block mounting plate
2 Sensor - Boiler flow 24 Left side hand-hold for lifting boiler
3 Removable panel - for servicing 25 Gas valve
4 Electrode assembly 26 Flue air pressure switch connection (not used)
5 Overheat thermostat 27 Fan
6 Securing nut - Air/Gas manifold clamp 28 Fan guard
7 Silicon tube - heat exchanger air vent 29 Manual vent point
8 Heat exchanger 30 Fan pressure test point
9 Flue over heat thermostat 31 Air/Gas manifold
10 Access panel - Heat exchanger/sump cleaning 32 Compact hydraulic - left mounting point
11 Right side hand-hold for lifting boiler 33 Flow connector from heat exchanger
12 Diverter valve assembly (body) 34 Expansion vessel hose connection point
13 Diverter valve actuator (stepper motor blank) 35 Auto air vent
14 Pump 36 Return connection to heat exchanger
15 Drain point 37 Flow turbine housing (not used on i System)
16 Central Heating (CH) return isolator 38 Unused port
17 System pressure gauge 39 Compact hydraulic - right mounting point
18 Control panel (in service position) 40 Pressure relief valve
19 Cover - external wiring connections 41 CH return connection to service valve
20 Cover - transformer and PCB 42 Internal by-pass
21 Gas inlet connection 22 mm 43 CH flow connection to service valve
22 Central Heating (CH) flow isolator 44 Pressure gauge connection point
Tab. 7 Boiler components
6720644743-03.1Wo
32 33 23 3534 36 37
38
39
40
44
43
12
42 15 41
14
13

APPLIANCE INFORMATION
6 720 644 743a (2010/10)
10
Fig. 4 Additional components
1 Burner ON indicator light (green) 9 PRV pipe connection point
2 Power ON/OFF indicator/fault diagnostic light (blue) 10 CH return isolator
3 Position for optional programmer 11 Gas inlet connection 22 mm
4 Reset button 12 CH flow isolator
5Systempressuregauge 13 Condensate connection
6 ECO button (not used) 14 CH temperature control
7 DHW temperature control* 15 Service mode button
8 Boiler identification label
Tab. 8 Additional boiler components
6720644743-04.1Wo
123 45
6
15
14
91011
13 12
7
8
* The DHW temperature control is only
operational when the “Optional Internal
Diverter Valve” is fitted.

PRE-INSTALLATION
6 720 644 743a (2010/10) 11
3 PRE-INSTALLATION
3.1 CLEANING PRIMARY SYSTEMS
BEFORE CLEANING THE SYSTEM:
BEnsure that the system and pipe work is in good
working order.
BWhere possible keep the existing boiler/circulating
pump in place when flushing the system.
FOLLOW THE GUIDANCE OF BS7593:
Treatment of water in domestic hot water central
heating and also the flushing guidelines below.
FLUSHING THE SYSTEM
BFill the system with cold water and check for leaks.
BOpen all drain cocks and drain the system.
BClose drain cocks and add a suitable flushing agent
compatible with aluminium at the correct strength
for the system conditions 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.
BCirculate the flushing agent before the boiler is fired
up.
BRun the boiler/system at normal operating
temperature as directed by the manufacturer of the
flushing agent.
BDrain and thoroughly flush the system to remove the
flushing agent and debris.
BIt may be necessary to use a power flushing machine
to aid the cleansing procedure in some
circumstances.
BClose the drain cocks and refill with fresh water and
a suitable inhibitor.
BVent any air from the boiler and system.
INHIBITOR
Add a suitable inhibitor or combined inhibitor/anti-
freeze, if the system is exposed to freezing conditions, to
the heating system in accordance with the DWTA code of
practice and manufacturer‘s guidelines.
NOTICE:
BAll the following Pre-Installation sections
must be read and requirements met
before starting boiler or flue installations.
CAUTION:
BISOLATE THE MAINS SUPPLIES BEFORE
STARTING ANY WORK AND OBSERVE ALL
RELEVANT SAFETY PRECAUTIONS.
NOTICE:
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.
NOTICE: ARTIFICALLY SOFTENED WATER
MUST NOT BE USED TO FILL THE CENTRAL
HEATING SYSTEM.
WARNING: Sealing agents
BThe addition of sealing agents to the
system water is not permitted as this can
cause problems with deposits left in the
heat exchanger.

PRE-INSTALLATION
6 720 644 743a (2010/10)
12
3.2 MAINS SUPPLY
3.2.1 ELECTRICAL SUPPLY
•Supply: 230V - 50 Hz, 140 Watts
•Cable: PVC insulated 0.75 mm2(24 x 0.2 mm)
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.
•Wiring must comply with the latest IEE wiring
regulations.
3.2.2 EQUIPOTENTIAL BONDING
MAIN EQUIPOTENTIAL BONDING
Main equipotential bonding is carried at the origin of the
electrical installation and connected to the main
electrical earthing terminal.
Metal pipes can be used as bonding conductors if joints
are metal to metal and electrically continuous.
The IEE Wiring Regulations (BS 7671:2008) require that
extraneous conductive parts must be connected to the
main electrical earth.
The main bonding of incoming metallic services must be
as close as practical to their entry point, before any
branch pipe work and a maximum of 600mm from an
internal meter.
Bonding conductors must be copper and the same size
as other bonding conductors and not less than 10mm2.
The bonding conductors must be permanently fixed to
the metal pipes with clamps and labels (to BS 951) in a
visible position to allow for inspection.
SUPPLEMENTARY BONDING
Supplementary bonding is normally carried out in an
area of increased shock risk e.g. bathrooms.
Consult a qualified electrician for them to determine if
the installation requires supplementary bonding as
specified in the 17th edition of the IEE Wiring
regulations (BS 7671:2008).
3.2.3 GAS SUPPLY
•Boilers using Natural Gas (NG) must be connected to
a governed meter.
•Liquid Petroleum Gas (LPG) must be connected to a
regulator.
•Installation and connection of the gas supply to the
boiler must be in accordance with BS6891.
•Under no circumstance should be size of the gas
supply pipe be less than 22 mm.
•The meter or regulator and pipe work to the meter
must be checked, preferably by the gas supplier.
This is to ensure that the equipment 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.
NOTICE: This is reduced to IP20 if the
following mechanical timers are fitted;
7 716 192 036 or 7 716 192 037

PRE-INSTALLATION
6 720 644 743a (2010/10) 13
3.3 WATER SYSTEM AND PIPE WORK
PLASTIC PIPE WORK:
•Any plastic pipe work must have a polymeric barrier
with 600mm (minimum) length of copper pipe
connected to the boiler.
•Plastic pipe work used for underfloor heating must be
correctly controlled with a thermostatic blending
valve limiting the temperature of the circuits to
approximately 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 lock-shield 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.
SEALED PRIMARY SYSTEM:
•The CH sealed system must be filled using a WRAS
approved filling loop or comply with figure 5 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 (2) must be fitted as close
as possible to the appliance in the central heating
return.
•Pressurise the extra expansion vessel (2) to the same
figure as the expansion vessel built into the appliance.
•Do not use galvanised pipes or radiators.
SYSTEM FILL
Fig. 5 System fill
Fig. 6 Additional expansion vessel
The boiler is equipped with an automatic
internal by-pass.
NOTICE: ARTIFICALLY SOFTENED WATER
MUST NOT BE USED TO FILL THE CENTRAL
HEATING SYSTEM
1 Appliance expansion vessel - CH
2 Extra expansion vessel - CH return
3 Pressure relief discharge
Tab. 9 Key to fig. 5
SYSTEM FILL
CV = Check Valve
SV = Stop Valve
SV SV
Test point
Temporary hose
Hose union CV
CV
Heating
return Mains
supply
SYSTEM MAKE UP
AA = Auto Air vent
CV = Check Valve
SV = Stop Valve
SV CV
AA Make up
vessel
Heating
return
1000 mm (39 in)
above the highest
point of the system.
Fill point
6720644743-08.1Wo
1
2
3
6720644743-09.1Wo

PRE-INSTALLATION
6 720 644 743a (2010/10)
14
S AND Y PLAN SYSTEMS:
OPTIONAL DIVERTER VALVE
This boiler is designed to operate on a sealed system
only. The boiler will require a second return pipe from
the water cylinder to the wall mounting frame and
terminate in 15mm copper pipe.
S PLAN LAYOUT
Fig. 7
Y PLAN LAYOUT
WITH EXTERNAL DIVERTER VALVE
Fig. 8
SYSTEM LAYOUT
WITH OPTIONAL INTERNAL DIVERTER VALVE
(NOT SUPPLIED WITH BOILER)
Fig. 9
NOTICE: The boiler is fitted with its own
internal bypass.
1 Diverter valve
2 Radiator valve (flow)
3 Lock shield valve (return)
4Bypass
Tab. 10
NOTICE:
BA drain cock should be fitted at the
lowest point of the heating circuit and
beneath the appliance.
3
2
1
4
M
M
6720644743-05.1Wo
3
2
1
M
6720644743-06.1Wo
Boiler flow
Cylinder return
Heating return
)
3
2
6720644743-07.1Wo

PRE-INSTALLATION
6 720 644 743a (2010/10) 15
3.4 CONDENSATE PIPE WORK
3.4.1 INTERNAL CONNECTIONS
In order to minimise risk of freezing during prolonged
cold spells, the following methods of installing
condensate drainage pipe should be adopted, in order of
priority.
Wherever possible, the condensate drainage pipe should
be routed and terminated so that the condensate drains
away from the boiler under gravity to a suitable internal
foul water discharge point such as an internal soil and
vent stack. A suitable permanent connection to the foul
waste pipe should be used.
Fig. 10 Disposal to soil vent stack
Alternatively if the first option is not possible an internal
kitchen or bathroom waste pipe, washing machine
waste pipe etc. can be used.
Fig. 11 Disposal to a waste pipe
CONDENSATE PUMP
Where “gravity discharge” to an internal termination is
not physically possible, or where very long internal runs
would be required to reach a suitable discharge point,
condensate should be removed using a proprietary
condensate pump, of a specification recommended by
the boiler or condensate pump manufacturer.
The pump outlet pipe should discharge to a suitable
internal foul water discharge point such as an internal
soil and vent stack, internal kitchen or bathroom waste
pipe, washing machine waste pipe etc. A suitable
permanent connection to the foul waste pipe should be
used.
Fig. 12 Condensate pump disposal
NOTICE:
BWhere a new or replacement boiler is
being installed, access to an internal
“gravity discharge” point should be one
of the factors considered in determining
boiler location.
BThe condensate pipe must be a minimum
of 22 mm Ø plastic pipe.
BThe condensate pipe work must fall at
least 50 mm per metre towards the outlet
and should take the shortest practicable
route.
BEnsure there are no blockages in the pipe
run.
Key to condensate illustrations
1 Syphon trap
2 Soil and vent stack
3 Minimum 450mm and up to three storeys
4 Visible air break at plug hole
5 Sink or basin with integrated overflow
6 75 mm sink waste trap
7 Condensate pump
2
22mm Ø
1
3
6720644744-06.1Wo
100mm
75mm
min.
4
5
6
1
22mm Ø
6720644744-07.1Wo
75mm
min.
4
7
5
6
1
22mm Ø
6720644744-08.1Wo

PRE-INSTALLATION
6 720 644 743a (2010/10)
16
3.4.2 EXTERNAL CONNECTIONS
If no other discharge method is possible then the use of
an externally run condensate drainage pipe terminating
at a suitable foul water discharge point, or purpose-
designed soak away, may be considered.
If this method is chosen then the following measures
should be adopted:
BThe external run be kept as short as possible and not
exceed three metres.
BThe pipe should be run internally as far as possible
before going externally and the pipe diameter should
be increased to 32mm before it passes through the
wall to the exterior. The pipe should be insulated
using suitable waterproof and weather resistant
insulation.
BThe external pipe should take the shortest and least
exposed route to the discharge point, and should
"fall" as steeply as possible away from the boiler, with
no horizontal runs in which condensate might stand.
BThe use of fittings, elbows etc. should be kept to a
minimum and any internal “burrs” on cut pipe work
should be removed so that the internal pipe section is
as smooth as possible.
FITTING AN EXTERNAL AIR BREAK
•Refer to figure 13. When a rain water down pipe, that
goes directly into a sewer that carries both rainwater
and foul water, is used to dispose of condensate.
•An air break must be installed in the 43 mm pipe work,
between the boiler condensate outlet and the
drainpipe, outside the property, to avoid flooding
during adverse weather conditions.
Fig. 13 Disposal into a rainwater down pipe
Where the pipe terminates over an open drain or gully,
the pipe should terminate below the grating level, but
above water level, in order to minimise “wind chill” at
the open end.
The use of a drain cover (such as those used to prevent
blockage by leaves) may offer further protection from
wind chill.
Pipe drainage will be improved if the end is cut at 45°
angle as opposed to a straight cut.
Fig. 14 External disposal
NOTICE: Freezing conditions
BPipe work length should be kept to a
minimum and the route as vertical as
possible.
BWhere pipe work is subjected to extreme
cold or wind chill, a weather proof
insulation should be used.
NOTICE: Condensate waste
BCare should be taken when siting a soak-
away to avoid obstructing existing
services.
Continued - Key to condensate illustrations
8 68mm Ø PVCu strap on fitting
9 100 mm Ø minimum plastic pipe
10 Drainage holes
11 Limestone chippings
12 Bottom of sealed tube
13 Insulate and increase pipe size
14 Pipe work transition
15 External air break
16 Air gap
17 External rain water pipe into foul water
Condensate drainage pipe can be run above
or below ground.
78
13
14
17
15
16
1
6720644744-09.1Wo
25mm min.
14
13
1
6720644744-10.1Wo

PRE-INSTALLATION
6 720 644 743a (2010/10) 17
CONDENSATE SOAK AWAY
•The condensate drainage pipe may be run above or
below the ground to the soak away.
•The examples shown on this page run above ground.
•The soak away must use a 100mm Ø 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 400 mm.
In situations where there are likely to be extremes of
temperature or exposure, the use of a proprietary trace-
heating system for external pipe work, incorporating an
external frost thermostat, should be considered. If such
a system is used, the requirement to use 32mm pipe
does not apply, however all other guidance above, and
the instructions for the trace heating system, should be
closely followed.
Fig. 15 Soak away
Fig. 16 Condensate pump to external disposal
Minimum hole size for the condensate soak
away must be 400mm deep by 300mmØ .
NOTICE: Unheated internal areas.
BInternal pipe runs in unheated areas such
as lofts, basements and garages should
be treated as external runs.
13
14
10
500mm min.
25mm min.
400mm
min.
1
12
11
9
6720644744-11.1Wo
9
10
25mm min.
14 13
1
7
6720644744-12.1Wo

PRE-INSTALLATION
6 720 644 743a (2010/10)
18
3.5 PRESSURE RELIEF PIPE WORK
•The pressure relief drain pipe (1) from the boiler
should be at least 15mm diameter copper pipe and
run downwards, away from any electrical equipment
or other hazard, preferably to an external drain or
soak away.
•Pipe (1) should be finished with a partial bend, near
the outlet to face the external wall (as shown) to help
prevent freezing.
Fig. 17 Pressure relief pipe work
NOTICE:
BThe pressure relief valve is a safety device
for the boiler and if activated may
discharge boiling water steam through
the relief valve drain pipe.
BCare 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.
2Outsidewall
1,3 Drain pipe
4Externaldrain
Tab. 11 Key to fig 7
6720643895-08.1Wo
1
2
3
4

PRE-INSTALLATION
6 720 644 743a (2010/10) 19
3.6 BOILER LOCATION AND CLEARANCES
3.6.1 INSTALLATION
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.
3.6.2 SERVICING CLEARANCES -
VENTILATED COMPARTMENT
Figure 18 shows the minimum space required to install
and service the boiler in a ventilated compartment.
•If a boiler is installed in a compartment with
clearances less than shown in the tables 14, 15,
or 16 ventilation is required. Refer to table 12 for
ventilation requirements.
Fig. 18 Ventilated compartment
3.6.3 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 ancillary equipment.
•If fitting the boiler into an airing cupboard use a non-
combustible material to separate the boiler from the
airing space.
The material can be perforated up to a maximum hole
size of 13mm.
3.6.4 BATHROOMS
A boiler fitted with a non-mechanical timer or with no
timer can be installed in zone 2 or outside the shaded
area .
A boiler with a mechanical timer or RF mechanical timer
with room thermostat must only be installed outside the
shaded area.
Additional RCD (Residual Current Device) protection
may be required.
Refer to the latest IEE wiring regulations.
Fig. 19 Bathroom installations
NOTICE:
No surface protection is required against
heat transfer from the boiler
Vent position
To room or
internal space
Direct to
outside
High level Minimum free
area 122 cm2
Minimum free
area 61 cm2
Low level Minimum free
area 122 cm2
Minimum free
area 61 cm2
Tab. 12 Compartment ventilation
*Minimum clearance to removable door
** Minimum clearance required for servicing
Tab. 13 Minimum clearances
6720643895-121.1Wo
+ 30 mm
above elbow
930 mm 410 mm
25 mm*
600 mm**
5 mm
Using 100 mm
flue kit
1080 mm
Using 125 mm
flue kit
1100 mm
200 mm
5 mm
600mm radius
600 mm
600 mm
750 mm
2250 mm
2250 mm
600 mm
2250 mm
600mm radius
750 mm
2250mm
6720643895-10.1Wo
11
1
1
2 2
2
2

PRE-INSTALLATION
6 720 644 743a (2010/10)
20
3.6.5 BOILER CLEARANCES - UNVENTILATED COMPARTMENTS
3.6.6 INSTALLATION CLEARANCES - UNVENTILATED COMPARTMENTS
The tables below show the options for the minimum space required to install and service the boiler inside an
unventilated compartment.
CAUTION: CLEARANCES
BTop and bottom clearances must not be reduced below the values shown in table 14 as they are the
minimum clearances required for servicing.
Unventilated Compartment Installation Clearances (millimetres)
The suggested total unventilated compartment minimum clearances are:
Side Above Below Front (to removable door)
400 170 approx. (30 above the elbow) 200 100
Tab. 14 Minimum unventilated compartment clearances
If Side Clearances are Reduced (millimetres)
If total side clearance is reduced to:
(Combined left and right clearances
excluding the appliance)
Increase height clearances to (approx):
(Combined top and bottom clearances
excluding the appliance)
OR Front clearance (to
removable door) must
be increased to:
350 441 129
300 523 161
250 617 200
200 717 243
150 856 295
100 1012 358
50 1202 434
Tab. 15 Reduced side clearances
If Front Clearance is Reduced (millimetres)
If front clearance (to
removable door) is
reduced to:
Increase overall height clearances to approx:
(Combined top and bottom clearances
excluding the appliance)
OR Increase total side clearance to:
(Combined left and right
clearances excluding the
appliance)
50 511 505
25 596 569
Tab. 16 Reduced front clearances