Bosch Worcester 7 716 192 566 User manual

UK/IE
INSTALLATION INSTRUCTIONS
WALL HUNG RSF GAS FIRED CONDENSING BOILER
GREENSTAR i SYSTEM OPTIONAL INTEGRAL
DIVERTER VALVE
6720645222-00.2Wo
FOR SEALED CENTRAL HEATING SYSTEMS AND INDIRECTLY MAINS FED DOMESTIC HOT WATER
6 720 645 222 (2012/09)
Diverter valve kit numbers
12kW 7 716 192 566
15kW 7 716 192 567
18kW 7 716 192 568
24kW 7 716 192 409
Diverter valve kits contain:
1 Copper return pipe
1 Brass service valve
1 15mm Compression nut
1 15mm Olive
1 Diverter valve motor and cover
1 Cylinder temperature sensor and lead
2Screws
2Codeplugs
1Codeplugtie
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
LPG
(Liquid
Petroleum Gas)
12i System 41-311-69
15i System 41-311-85
18i System 41-311-87
24i System 41-311-70
Read these instruction in conjunction with the
i System Installation, Commissioning
and Servicing instruction manual

CONTENTS
i System Diverter Valve kit 6 720 645 222 (2012/09)
2
CONTENTS
1 Key to symbols and safety precautions . . . . . . . . . . . . . . . . . . . 2
1.1 Explanation of symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Plumbing manifold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3 Boiler connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1 Assembly of internal cylinder return pipe to the boiler . . 4
3.2 Gas and water connections . . . . . . . . . . . . . . . . . . . . . . . 5
4 Fitting the diverter valve motor and code plug . . . . . . . . . . . . 6
4.1 Fitting the diverter valve motor: . . . . . . . . . . . . . . . . . . . . 6
4.2 Access to the code plug . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.3 Fitting the code plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 DHW monitoring and control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1 Cylinder temperature sensor/thermostat . . . . . . . . . . . . 7
5.1.1 Fitting the cylinder temperature sensor . . . . . . . . . . . . . 7
5.1.2 Fitting the cylinder thermostat . . . . . . . . . . . . . . . . . . . . . 7
5.2 Diverter valve and sensor connections . . . . . . . . . . . . . . 8
5.3 Diverter valve and cylinder thermostat connections . . . 8
6 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1 Internal diverter valve with a vented cylinder and DHW
cylinder sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.2 Internal diverter valve with a vented cylinder and DHW
cylinder thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.3 Internal diverter valve with an unvented
cylinder and DHW cylinder thermostat only . . . . . . . . . . 9
6.4 Position of wired components . . . . . . . . . . . . . . . . . . . 11
7 Pre-commissioning checks . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8 Boiler function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1 Fault finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.2 Boiler function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.3 Protection function . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1 KEY TO SYMBOLS AND SAFETY
INSTRUCTIONS
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.
ABBREVIATIONS USED IN THIS MANUAL:
NOTICE: Safety precautions and standards
▶ Refer to the relevant Installation, Commissioning and
Service instructions for Safety precautions and
British standards
Safety instructions in this document are framed and
identified by a warning triangle which is printed on a
grey background.
Important information in cases where there is no risk of
personal injury or material losses is identified by the
symbol shown on the left. It is bordered by horizontal
lines above and below the text.
Symbol Meaning
▶ a step in an action sequence
a reference to a related part in the document or to other
related documents
• a list entry
–a list entry (second level)
Domestic Hot Water
Central Heating
Hot Water Storage Cylinder
Domestic Cold Water Supply
Electrical Supply
Gas Supply
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.
These instructions apply in the UK and Ireland only and must be
followed except for any statutory obligations.
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 help-line
(0844 892 3366).
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.
Distance learning and training courses are available from Worcester.
The BENCHMARK CHECKLIST can be found in the back of the
Installation, Commissioning and Servicing instructions.
ØDiameter
NG Natural Gas
LPG Liquid Petroleum Gas
CH Central Heating
DHW Domestic Hot Water
PRV Pressure Relief Valve
PTC Positive Temperature Coefficient (sensor)
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 U.K.

PLUMBING MANIFOLD
i System Diverter Valve kit 6 720 645 222 (2012/09) 3
2 PLUMBING MANIFOLD
CONNECTIONS:
• Heating System: 22mm compression fittings
• Gas: 22mm compression fitting
• Cylinder Return 15mm compression fitting
• Use the fittings supplied in the Hardware literature pack and the
Optional Diverter Valve Kit.
If the boiler pipes are to be run behind the appliance ensure that the
pipes pass through the slot in the
guide (9). This is fitted to the boiler frame.
Fig. 1 Pipe dimensions
Fig. 2 Plumbing manifold with wall frame
NOTICE: Fitting the service valve
▶ Refer to figure 2
▶ The service valve (7) from the Optional Diverter Valve
Kit must be fitted and secured to the wall mounting
frame with two screws (8) supplied, before the wall
mounting frame is fitted to the wall.
Further guidance on pipe routing can be found printed
on the boiler template (supplied with the boiler).
123456
6720645222-12.1Wo
#Function
From left
case edge
Diameter of
pipe
1 CH and cylinder flow 70mm 22mm
2Gas 200mm 22mm
3CHReturn 330mm 22mm
4Condensate 35mm 22mm
5 Pressure Relief Valve 367mm 15mm
6 Cylinder return 267mm 15mm
7 Cylinder return isolation valve
8 Isolation valve mounting screws
9 Pipe guide
Table 1 Key to figures 1 & 2
6720645222-01.3Wo
12
3
123
6
6
7
8
9

BOILER CONNECTIONS
i System Diverter Valve kit 6 720 645 222 (2012/09)
4
3 BOILER CONNECTIONS
3.1 ASSEMBLY OF THE INTERNAL CYLINDER RETURN
PIPE TO THE BOILER
Use the packaging as protection, turn the boiler on its left hand side to
enable fitting of the hot water return pipe.
▶ Move the control panel into the service position by removing the
screw from the retaining bracket.
1. Loosen the two retaining screws to free the back clamping plate on the
hydraulic block as shown in figure 3.
2. Remove the brass bung assembly from the hydraulic block by
removing the screw and sliding it free from the flange on the clamping
plate. Make sure that the other brass bung assembly is retained in
place.
3. Remove the copper pipe from the Optional Integral Diverter Valve Kit
and feed the flat end of the pipe through the rear of the boiler as
shown.
4. Before fitting the pipe, check that the seal is in position on the plastic
moulding. Slide the flat end of the pipe under the flange on the
hydraulic block clamping plate ensuring that pipe is located correctly.
5. Secure the clamping plate by re-tightening the two screws (1)
loosened in step 1.
Fig. 3 Hot water return pipe fitting
NOTICE: CYLINDER RETURN PIPE
▶ The following must be completed before the boiler is
mounted onto the wall mounting frame
Re-secure the control panel before lifting the boiler.
4.
3.
2. 5.
1.
1.
6720645222-02.1Wo

BOILER CONNECTIONS
i System Diverter Valve kit 6 720 645 222 (2012/09) 5
3.2 GAS AND WATER CONNECTIONS
▶ Remove template and secure the wall mounting frame to the wall with
the fittings supplied.
▶ System pipes may be run vertically upwards behind the boiler or
below it.
See Plumbing Manifold Section on page 3.
1. CH and cylinder flow (22mm),
2. Gas inlet (22mm),
3. Cylinder return(15mm),
4. CH return (22mm)
▶ Fit sealing washers to service valves before hanging boiler.
Fig. 4 Sealing washers
1. Pull the extended tab/lever forward and down until there is no further
travel.
Fig. 5 PRV connection in the down position
▶ Hang the boiler on to the wall mounting frame by the two brackets
positioned left and right at the top rear of the appliance.
Do not lift the appliance by the air gas manifold. There are two
handling holes incorporated into the inner casing left and right in the
lower section of the appliance.
Fig. 6 Hanging the boiler
1. Push the lever on the pressure relief connector UP until the stop on
the inside of the handle is over the shoulder of the metal bracket to
secure in place.
Fig. 7 PRV in the up position
▶ Remove the screw from the control panel retaining bracket and lower
the control panel into the service position.
▶ Make connections to the heating system and cylinder.
Connect the gas supply to the boiler gas cock 22mm compression.
CAUTION: MAINS SUPPLIES:
▶ ISOLATE THE MAINS GAS SUPPLY BEFORE
STARTING ANY WORK AND OBSERVE ALL RELEVANT
SAFETY PRECAUTIONS.
The bonded washer supplied is for the gas connection
only.
NOTICE: PRV connector
▶ Before hanging the boiler onto the wall mounting
frameensurethatthepressurereliefvalveconnection
is in the DOWN position.
This is located on the right hand side of the wall frame
at the rear.
6720654222-11.4Wo
1. 2. 3. 4.
6720643895-116.2Wo
1.
NOTICE: Protective caps/strips
▶ Caps or plastic strip fitted to pipes must be removed
before hanging the boiler.
NOTICE: PRV connector
▶ The pressure relief connector must be repositioned
after the boiler has been correctly mounted to the wall
mounting frame.
6720643895-22.1Wo
6720644743-17.2Wo
1.

FITTING THE DIVERTER VALVE MOTOR AND CODE PLUG
i System Diverter Valve kit 6 720 645 222 (2012/09)
6
To connect the expansion vessel flexible pipe to the hydraulic manifold
situated to the left of the pump:
▶ Remove and discard the plastic cap from the expansion vessel flexible
pipe.
1. Refer to figure 8, release the retaining clip.
2. Remove and discard the orange plastic blanking plug (2) from the
pressure vessel connection at the hydraulic manifold.
Fig. 8 Blanking plug removal
1. Refer to figure 9 and insert the expansion vessel flexible pipe it to the
fitting on the pump.
2. Secure in place with the wire retaining clip.
Fig. 9 Expansion vessel connection
▶ Connect the pressure relief drain pipe to 15mm compression joint
using the compression nut and olive supplied in the literature/
hardware pack.
4 FITTING THE DIVERTER VALVE MOTOR
AND CODE PLUG
4.1 FITTING THE DIVERTER VALVE MOTOR:
1. Remove the diverter valve blanking plate by pulling it forwards to free
it from its location.
Fig. 10 Removing Diverter valve blanking plate
1. To fit the diverter valve motor, push the motor into the housing until
the motor “clicks” securely into place, ensuring that the actuator arm
locates into the middle of the “H” receptor on the motor.
2. Connect the plug of the diverter valve motor harness into the socket
on the diverter valve motor.
3. Slide the protective cover over the diverter valve motor.
Fig. 11 Fitting Diverter motor and cover
4.2 ACCESS TO THE CODE PLUG
1. Referring to figure 12, unscrew the three screws in the control panel.
2. Pull off the connections cover.
Fig. 12 Removing the connection cover
6720645222-05.1Wo
1.
2.
6720645222-06.1Wo
1.
2.
1.
6720645222-07.2Wo
3. 2.
1.
6720645222-08.2Wo
6720804530-01.1Wo
1.
1.
1. 2.

DHW MONITORING AND CONTROL
i System Diverter Valve kit 6 720 645 222 (2012/09) 7
▶ Identify ST18, the code plug and connector.
Fig. 13 Connector locations
4.3 FITTING THE CODE PLUG
1. Refer to figure 14 and remove the code plug from the controller, cut
the tie securing the plug to the boiler chassis and discard the plug and
tie.
2. Fit the code plug from the kit making sure that code plug is secured to
the boiler chassis with the new tie.
▶ Confirm that the number on the code plug corresponds to the boiler
type in the table above.
Fig. 14 Fitting new code plug
5 DHW MONITORING AND CONTROL
The diverter valve kit is supplied with a cylinder temperature sensor,
which is the better option when using Worcester's FX range of controls
with the boiler, refer to sections 5.1 and 5.2.
However a volt-free cylinder thermostat can be used instead and should
be wired to ST8, refer to section 5.3.
Do not use both methods of hot water control, choose one or the other
5.1 CYLINDER TEMPERATURE SENSOR/THERMOSTAT
5.1.1 FITTING THE CYLINDER TEMPERATURE SENSOR
Refer to the cylinder installation instructions for the position of the
sensor, there may already be a “sensor pocket” available. If no “pocket”
is available, for foam insulated cylinders only with no metal jacket, follow
the steps below.
1. Mark a rectangular hole of approximately 50 by 100mm about one
third of the cylinder length from the bottom of the cylinder.
1. Using a sharp knife, cut through the insulation, remove and retain the
piece of insulation.
2. Apply heat conductive paste to the sensor and place the sensor on the
cylinder body in the middle of the cut-out.
3. Hold the sensor in position with a piece of aluminium tape.
4. Replace the insulation material.
5. Secure the insulation in place with suitable cloth tape.
Fig. 15 Sensor connection to cylinder
5.1.2 FITTING THE CYLINDER THERMOSTAT
Refer to the cylinder installation instructions for the position of the
thermostat, there may already be a “pocket” available.
On foam insulated cylinders with no metal jacket and no “pocket” use a
strap thermostat. Cut out a suitable piece of insulation to accommodate
the thermostat and secure the thermostat with the strap.
NOTICE: RESET THE CONTROL BOARD
Following changes to the wiring of ST15 and ST8 the
control board will need to be reset to recognise the new
connection.
The power must be on to reset, all lights will flash to
confirm the reset.
To reset the control board:
▶ Hold the Service mode “Spanner” and the Eco buttons
down for at least five seconds.
Boiler size Gas Code plug no.
12kW i System kit NG 1118
LPG 1119
15kW i System kit NG 1122
LPG 1123
18kW i System kit NG 1126
LPG 1127
24kW i System kit NG 1114
LPG 1115
6720804530-03.1Wo
S11
ST10 ST6 ST19
ST18
6720645222-10.1Wo
1.
2.
ST18
Cylinder sensors can only be utilised on boilers with
DHW temperature control.
CAUTION: Cut carefully!
▶ Do not to pierce the wall of cylinder.
▶ Do not cut any metal insulation jacket.
NOTICE: Foam covered hot water cylinders
▶ Figure 15 applies only to foam covered open vented
cylinders.
6720645222-24.1Wo
6. 3.
4.
5.
2.
1.

ELECTRICAL
i System Diverter Valve kit 6 720 645 222 (2012/09)
8
5.2 DIVERTER VALVE AND SENSOR CONNECTIONS
1. Connect the cylinder temperature sensor (1) to the edge connector
ST15.
▶ Connect the Diverter valve motor harness to the Diverter valve motor
connection, refer to the circuit diagram in section 6.4.
Fig. 16 Diverter motor and sensor connections
▶ Replace the control panel cover.
▶ Move the control panel to the up position and secure.
5.3 DIVERTER VALVE AND CYLINDER THERMOSTAT
CONNECTIONS
1. Connect the cylinder thermostat (1) to the connector ST8.
▶ Connect the Diverter valve motor harness to the Diverter valve motor
connection, refer to the circuit diagram in section 6.4.
Fig. 17 Diverter motor and thermostat connections
▶ Replace the control panel cover.
▶ Move the control panel to the up position and secure.
6 ELECTRICAL
6.1 INTERNAL DIVERTER VALVE WITH A VENTED
CYLINDER AND DHW CYLINDER SENSOR
ACCESS TO ELECTRICAL CONNECTIONS:
Remove boiler casing to access control panel.
1. Unscrew the single screw and lower the control box into the horizontal
position.
2. Unscrew the three screws in the control panel and pull off the
connections cover.
3. 230V room thermostat with timer 7 716 192 038 (ST10):
▶ Remove link - LS/LR
▶ Connect room stat LIVE supply to terminal (LS)
▶ Connect room stat LIVE return to terminal (LR)
▶ Connect room stat NEUTRAL to terminal (NS)
4. Hot water channel
– Cylinder sensor connects to ST15
5. Optional external frost stat connection (ST6):
▶Connectfroststatwires to terminal (FS) and (FR)
6. Diverter valve motor:
▶ Connect the Diverter valve motor harness to the Diverter valve motor
connection, refer to the circuit diagram in section 6.4.
Fig. 18
NOTICE: Cable routing:
▶ Do not route low voltage cables alongside mains
voltage cables.
This can cause interference on the low voltage cables.
If the ST15 connector and sensor is being used do not
connect ST8 as well.
The link is not required.
If the ST8 and thermostat are being used do not use
ST15 as well.
The link is not required.
1
6720645222-11.3Wo
1.
ST15
ST8
ST17
1
6720645222-28.2Wo
1.
ST15
ST8
ST17
NOTICE: General information
▶ Mains supply to the boiler must be through a fused
double pole isolator situated adjacent to the
appliance. The isolator must have a contact
separation of 3mm minimum in both poles. External
fuse rating 3A.
▶ When stripping wires always ensure copper strands
do not fall into the control box.
▶ There should be no external wiring centre.
▶ A fascia mounted twin channel programmer must be
used. Timers available:
DT20 Twin Channel Programmer (7 716 192 038),
DT10RF Digistat (7 716 192 052),
DT10RF Optimiser (7 716 192 053)
DT20RF Digistat (7 716 192 054),
FR10 Intelligent room thermostat (7 716 192 065),
FR110 Programmable thermostat (7 716 192 066),
FW100 Weather compensation (7 716 192 067).
▶ If any of the programmers/timers listed above are
used, the room thermostat is incorporated in the
transmitter. Therefore keep link fitted across LS/LR.
6720645222-29.1Wo
L
NSN
LSLR
N
blue
brown
green/yellow
live
switched live
neutral
E
230V
MAINS
SUPPLY
L
Room
Thermostat
DT20 Twin Channel
Programmer
Cylinder
temperature
sensor
ST15

ELECTRICAL
i System Diverter Valve kit 6 720 645 222 (2012/09) 9
6.2 INTERNAL DIVERTER VALVE WITH A VENTED
CYLINDER AND DHW CYLINDER THERMOSTAT
ACCESS TO ELECTRICAL CONNECTIONS:
Remove boiler casing to access control panel.
1. Unscrew the single screw and lower the control box into the horizontal
position.
2. Unscrew the three screws in the control panel and pull off the
connections cover.
3. 230V room thermostat with timer 7 716 192 038 (ST10):
▶ Remove link - LS/LR
▶ Connect room stat LIVE supply to terminal (LS)
▶ Connect room stat LIVE return to terminal (LR)
▶ Connect room stat NEUTRAL to terminal (NS)
4. Hot water channel
– Volt free cylinder thermostat (ST8)
– Cylinder thermostat connects to ST8 terminals 7 and 9
5. Optional external frost stat connection (ST6):
▶Connectfroststatwires to terminal (FS) and (FR)
6. Diverter valve motor:
▶ Connect the Diverter valve motor harness to the Diverter valve motor
connection, refer to the circuit diagram in section 6.4.
Fig. 19 Vented cylinder with DHW thermostat
6.3 INTERNAL DIVERTER VALVE WITH AN UNVENTED
CYLINDER AND DHW CYLINDER THERMOSTAT ONLY
HOT WATER CHANNEL
▶ The wiring of the unvented cylinder dual thermostat must be
electrically separate.
▶ The cylinder dual thermostat must be connected to terminals 7 and 9.
▶ Any factory fitted links within the dual thermostat must be removed.
▶ The safety limit thermostat must be wired to interrupt the mains 230
Volt supply to the boiler terminal S10.
Fig. 20 Unvented cylinder with DHW thermostat
NOTICE: Programmers/Timers:
▶ If any of the programmers/timers listed inthe notice at
beginning of chapter 6 are used, the room thermostat
is incorporated in the transmitter. Therefore keep link
fitted across LS/LR.
NOTICE: ST8 Cylinder thermostat
▶ The cylinder thermostat must be volt free, i.e. not
connected to any voltage source.
6720645222-23.1Wo
L
ST8
NSN
LSLR
Nblue
brown
green/yellow
live
switched live
neutral
E
230V
MAINS
SUPPLY
L
Room
Thermostat
HOT WATER
CONTROL
THERMOSTAT
7
89
NOTICE: ST8 Cylinder thermostat
▶ The cylinder dual thermostat must be volt free, ie. not
connected to any voltage source.
NOTICE: RESET THE CONTROL BOARD
Following changes to the wiring of ST15 and ST8 the
control board will need to be reset to recognise the new
connection.
The power must be on to reset, all lights will flash to
confirm reset.
To reset the control board:
▶ Hold the Service mode “Spanner” and the Eco buttons
down for at least five seconds.
6720645222-20.3Wo
L
ST8
NSN
LSLR
Nblue
brown
green/yellow
live
switched live
neutral
E
230V
MAINS
SUPPLY
L
Room Thermostat
HIGH LIMIT
THERMAL CUT-OUT
HOT WATER CONTROL
THERMOSTAT
DUAL THERMOSTAT
*
7
89

ELECTRICAL
i System Diverter Valve kit 6 720 645 222 (2012/09)
10
OPTIONAL EXTERNAL FROST STAT CONNECTION ST6
Fig. 21 Frost Thermostat
▶ Connect frost thermostat cables to terminals FS& FR.
▶ These are not polarity sensitive.
CONNECTOR LOCATIONS
Fig. 22 Connector locations
S11 Fuse F1 2.5A
ST6 Frost thermostat connection
ST8 Optional cylinder stat
ST10 Mains in & external controls connections
ST18 Code plug
ST19 EMS BUS connection
NOTICE: RESET THE CONTROL BOARD
Following changes to the wiring of ST15 and ST8 the
control board will need to be reset to recognise the new
connection.
The power must be on to reset, all lights will flash to
confirm reset.
To reset the control board:
▶ Hold the Service mode “Spanner” and the Eco buttons
down for at least five seconds.
Frost Thermostat
FSFR NP LP
ST6
6720643895-43.1Wo
6720804530-03.2Wo
S11
ST10 ST6 ST8 ST19
ST18

ELECTRICAL
i System Diverter Valve kit 6 720 645 222 (2012/09) 11
6.4 POSITION OF WIRED COMPONENTS
6720645222-22.4Wo
FAN
FSFR NP LP
L
NSN
LSLR
ST8
ST9
ST17
ST18
ST5 ST4
ST10
Earth
MAINS
SUPPLY
PUMP
SUPPLY
SPARK
TRANSFORMER
DIVERTER
VALVE
ST1 DIAGNOSTIC
INTERFACE
CODE PLUG
Fuse F1, slow
2.5 A, AC 230 V
ST6
CH TEMPERATURE
CONTROL
Red
Neutral Supply
230V
EXTERNAL
ROOM STAT
WHEN USED
WITH DT20
WORCESTER 24V CONTROLS, PLUG IN POINT
OPTIONS: DT20 OR DT20 RF OR DT10 RF
(under blanking cover on fascia)
Live Supply
Live Return
Neutral
Live
Orange
Blue
Yellow
Green
Black
Colour sequence †
Purple
Purple
Red
Red
Orange
Orange
Colour sequence †
*
PRE WIRED LINK
*
EMS BUS contacts
(for FX controls)
Outside sensor
(FW 100)
B
B
4
2
1
A
F
Wall plate contacts
(for FX controls)
BB
EXTERNAL
FROST STAT
(OPTIONAL)
ST15
Optional cylinder
temperature
sensor
FLAME SENSE
ELECTRODE
SPARK
ELECTRODES
OVERHEAT
STAT
FLUE
OVERHEAT
STAT
PUMP
Green
DHW TEMPERATURE
CONTROL (CYLINDER)
GAS
VALVE
SAFETY
SOLENOID
SAFETY
SOLENOID
† Fan wiring:
Live = purple
Neutral = brown FLOW TEMP.
SENSOR (NTC)
SI1
Blue
Blue
230V~
Fuse F3, slow T 0.5 A
Fuse F2, slow T1.6 A
SI2
SI3
7
89
TANK STAT
(OPTIONAL)

PRE-COMMISSIONING CHECKS
i System Diverter Valve kit 6 720 645 222 (2012/09)
12
7 PRE-COMMISSIONING CHECKS
1. Check that the service and water pipes are connected to the correct
position on the manifold.
– 1 - CH and cylinder flow (22mm)
– 2 - Gas inlet (22mm)
– 3 - Cylinder Return (15mm)
– 4 - CH Return (22mm)
Fig. 23 Pipe connections
2. Check the gas type specified on the identification plate matches that
of the gas supply. Turn on the main gas supply, check the gas
pipework, connections and rectify any leaks.
3. Check that the condensate pipe has been connected to the syphon.
4. Check pressure relief drain pipe is correctly fitted and securely
tightened.
8 BOILER FUNCTION
8.1 FAULT FINDING
If in the unlikely event the boiler does not give complete satisfaction,
before calling for a service engineer, the installer should check the
following:
FOR BOILERS WITH INTEGRAL DIVERTER VALVE AND CONTROLS
NO CENTRAL HEATING, BUT HOT WATER OK
Remove the room stat wiring from LS, LRand N from terminal block
ST10. Fit a link between LSand LR, if the CH now works there is likely to
be a problem with the room stat or wiring to it.
NO HOT WATER, BUT CENTRAL HEATING OK
If a cylinder thermostat is used, remove the cylinder stat wiring from 7
and 9 on the terminal block ST8. Fit link across 7 and 9.
If the HW now functions, the problem may be with the cylinder
thermostat or wiring to the thermostat.
FOR ALL BOILERS WITH INTERNAL OR EXTERNAL CONTROLS
Burner lights then goes out in DHW or CH mode
Does the boiler run normally with the front cover off and then fail when
the cover is put back on?
If yes there is likely to be a flue problem - either the air inlet is blocked or
the inner flue is leaking flue gases into the air inlet.
BOILER NOISY OR GOING TO OVERHEAT
1. Was the system flushed?
2. Has the pump been bled and the dust cap released?
GENERAL CHECKS
1. Is all the air bled from the gas supply?
2. Is all the air bled from the primary water system?
3. Is there 230v a.c. across the boiler live and neutral terminals?
(L & N on ST10)
4. Is the polarity correct?
5. Is the incoming gas pressure at least 16.5mbar at the gas valve with
the boiler at maximum output?
NOTICE: If the boiler is not to be commissioned
immediately then:
▶ after successfully completing all of the checks and any
rectification work, close the gas and water valves,
shut off the gas supply, electrically isolate the boiler
and label appropriately.
NOTICE:
▶ NOW RETURN TO THE I SYSTEM INSTRUCTION
MANUAL (FILLING THE SYSTEM) TO CONTINUE
INSTALLATION.
6720654222-11.4Wo
1. 2. 3. 4.
Do NOT link out the cylinder sensor, it is a PTC device.
Only link out the cylinder thermostat to check the
operation of the boiler.

BOILER FUNCTION
i System Diverter Valve kit 6 720 645 222 (2012/09) 13
8.2 BOILER FUNCTION
Fig. 24 Boiler function
NO
YES
MAINS
POWER
SUPPLY
ON
BOILER
DEMAND
Fan to
start
speed.
Pump ON.
IGNITION
SEQUENCE
(see detail)
BLUE
LIGHT
ON
BURNER
LIT?
GREEN
FLAME
LIGHT
ON
Stop spark
and gas.
Wait
10 seconds
5th
attempt?
LOCKOUT
10 second
stabilisation
period.
Fan
modulation
to achieve
set
temperature
(40-82°C)
END OF
BOILER
DEMAND
Gas valve
OFF
Pump run 3
minutes
Fan run 30
seconds
Over temperature shut-
down if water tempera-
ture is 5°C above set
value.
Gas valve OFF.
Fan overrun
30 seconds
3 minute pump
over run
Spark
ignition and gas
4 seconds
NO
YES
Room
thermostat and/or
mains
programmer ON
(or link fitted at
ST10)
AND
Facia mounted
programmer (if
fitted) ON
AND
CH control knob
ON
IGNITION SEQUENCE
6720645222-25.1Wo
Diverter valve
CH position down
Cylinder position up

BOILER FUNCTION
i System Diverter Valve kit 6 720 645 222 (2012/09)
14
8.3 PROTECTION FUNCTION
Fig. 25 Protection function
Internal boiler
temperature
between
8°C & 5°C
Boiler automatic
frost function
(monitors internal boiler
primary temperature)
Internal boiler
temperature
below 5°C
Internal boiler
temperature
rises above 9°C
Pump runs
Pump switches off
after a 3 minute
overrun period
Internal boiler
temperature
rises above 12°C
Central heating
demand switches
off
Pump switches off
after a 3 minute
overrun period
Central heating
demand is activated
Pump runs for 3 minutes
to dissipate heat from
the boiler into the system
End of boiler demand
(central heating or
domestic hot water)
AUTOMATIC INTERNAL FROST FUNCTION
PUMP OVERRUN FUNCTION
A central heating demand
activated, pump runs
normally
Pump runs 5 seconds
every 24hrs from
last time pump ran
No central heating
demand after
a 24hr period
PUMP ANTISEIZE FUNCTION
6720643895-111.1Wo

i System Diverter Valve kit 6 720 645 222 (2012/09) 15
NOTES

Worcester, Bosch Group
Cotswold Way, Warndon, Worcester WR4 9SW.
Tel. [phone]
Worcester, Bosch Group is a brand name of Bosch Thermotechnology Ltd.
worcester-bosch.co.uk
6 720 645 222 (2012/09)
WORCESTER, BOSCH GROUP:
TECHNICAL SUPPORT: 0844 892 3366
APPOINTMENTS: 0844 892 3000
SPARES: 01905 752571
LITERATURE: 0844 892 9800
TRAINING: 01905 752526
SALES: 01905 752640