Worcester ZWBR 7-28 HE plus User guide

Installation and Servicing Instructions
GREENSTAR HE plus combi
Wall mounted condensing boiler for central heating and mains
fed domestic hot water
6 720 610 598-00.1
O
ZWBR 7-28 HE plus GC-Number: 47 311 56
ZWBR 11-35 HE plus
GC-Number: 47 311 57
6 720 610 597 GB (01.07) OSW

6 720 610 597 GB (01.07)
2
Contents
Contents
Safety precautions 3
Symbols 3
1 Details of the appliance 4
1.1 EC Declaration of Conformity 4
1.2 Standard package 4
1.3 Description of appliance 4
1.4 Accessories 5
1.5 Casing dimensions 5
1.6 Layout of appliance 6
1.7 Function 7
1.8 Electrical wiring diagram 8
1.9 Technical data 9
2 Installation regulations 11
3 Installation 11
3.1 Important remarks 11
3.2 Domestic hot water 12
3.3 Sealed systems 12
3.4 Siting the appliance 13
3.5 Wall mounting frame assembly 14
3.6 Pre-piping the system 14
3.7 Fitting the appliance 15
3.8 Checking the connections 16
3.9 Flue Systems 16
3.9.1 Siting the Flue Terminal 17
3.9.2 Installation of the flue 18
3.9.3 Flue duct preparation and assembly 20
4 Electrical connections 21
4.1 Connecting the appliance 21
4.2 Connecting TR2 Room thermostat 22
4.3 Mains Voltage external controls connections 22
5 Commissioning 23
5.1 Commissioning 23
5.2 Switching the appliance on/off 24
5.3 Switching on the central heating 24
5.4 System controls 24
5.5 Setting the domestic
hot water temperature and flow rate 25
5.5.1 Domestic hot water temperature 25
5.5.2 Hot water flow rate 25
5.6 Summer mode (hot water only) 25
5.7 Frost protection 25
5.8 Pump anti-seize function 25
5.9 Fault Condition 26
6 Text Display 27
6.1 General Description 27
6.2 Programming 27
6.2.1 Deleting a setting 28
6.2.2 Resetting all parameters
to their original settings 28
6.3 Menu structure 28
6.4 Setting the time/day 29
6.4.1 Setting the time and day 29
6.4.2 Holidays 29
6.5 Heating 29
6.5.1 Heating programme 29
6.5.2 Setting the Economy temperature 30
6.6 Hot water 30
6.6.1 Hot water programme 30
6.6.2 Hot water immediately 30
6.7 i Info 30
6.8 Settings 31
6.8.1 Heating (TR 2) 31
6.8.2 Hot Water
(Storage Tank, ZSBR models only) 31
6.8.3 Service 31
6.9 Individual timer programmes 31
7 Individual settings 32
7.1 Mechanical settings 32
7.1.1 Checking the size of the expansion vessel 32
7.1.2 Setting the central heating flow temperature 32
7.2 Settings on the Bosch Heatronic 32
7.2.1 General description 32
7.2.2 Setting the anti-cycle time
(Service Function 2.4) 33
7.2.3 Setting the maximum CH flow temperature
(Service Function 2.5) 33
7.2.4 Setting the heating output
(Service Function 5.0) 33
7.2.5 Constant hot water cycle time
(Service Function 6.8) 33
7.2.6 Variable pump settings
(Service Function 7.0) 33
7.3 Setting the gas/air ratio 33
8 Converting the appliance
to different gas types 34
8.1 Setting the gas/air ratio 34
8.2 Testing combustion air/flue gas at
set heat output 35
8.2.1 Testing the O
2
or CO
2
level
in the combustion air 35
8.2.2 Testing CO and CO
2
36
9 Maintenance 36
9.1 Pre-Service Check List 37
9.2 Description of servicing operations 38
9.3 Replacement of Parts 41
9.3.1 PCB control board and transformer 41
9.3.2 Fan Assembly 42
9.3.3 Pump 42
9.3.4 3-way diverter valve 43
9.3.5 3-way diverter valve motor 43
9.3.6 Sensors 43
9.3.7 Gas Valve 44
9.3.8 Domestic Hot Water Heat Exchanger 44
9.3.9 Electrode assembly 44
9.3.10Pressure gauge 44
9.3.11Expansion vessel 44
9.3.12Pressure Relief Valve 44
9.3.13Burner 44
9.3.14Flow switch 45
9.3.15Primary Heat Exchanger 45
10 Appendix 46
10.1 Fault Codes 46
10.2 Short parts list 47
10.3 Heating/hot water output settings
ZWBR 7-28 N.G. 48
10.4 Heating/hot water output settings
ZWBR 11-28 L.P.G 48
10.5 Heating/hot water output settings
ZWBR 11-35 N.G. 49
10.6 Heating/hot water output settings
ZWBR 14-35 L.P.G 49
10.7 Operational Flow diagrams 50
10.7.1Domestic hot water function 50
10.7.2Central heating function 51

6 720 610 597 GB (01.07)
Safety precautions
3
Safety precautions
If you smell gas
y Turn off gas service cock at the meter.
y Open windows and doors.
y Do not operate any electrical switches.
y Extinguish any naked flames.
y Telephone your gas company.
If you smell fumes from the appliance
y Switch off appliance (see page 24).
y Open windows and doors.
Fitting and modifications
y Fitting of the appliance or any controls to the appli-
ance may only be carried out by a competent engi-
neer in accordance wth the Gas Safety (Installation
and Use) Regulations 1998.
y Flue systems must not be modified in any ways other
than as described in the fitting instructions.
y This appliance is for use on sealed primary systems
only.
Maintenance
y The user is recommended: to have the system
regularly serviced in order to ensure that it functions
reliably and safely.
y Use only original spare parts!
Combustible materials
y Do not store or use any combustible materials
(paper, thinners, paints etc.) in the vicinity of the
appliance.
Health and safety
y This appliance contains no asbestos products.
y There is no potential hazard due to the appliance
being electrically unsafe.
y There are no substances used in the construction
that are a potential hazard in relation to the COSHH
Regulations (Control of Substances Hazardous to
Health Regulations 1988).
Combustion air/Ambient atmosphere
y The combustion air/ambient atmosphere should be
kept free of chemically aggressive substances (e.g.
halogenated hydrocarbons which contain chlorine or
fluorine compounds). This will prevent corrosion.
Instructions to the customer
y Explain to the customer how the appliance works and
how to operate it.
y Advise the user that he/she must not make any modi-
fications to the appliance or carry out any repairs on it.
y These instructions are to be left with the user or at
the Gas meter.
y Important: These instructions apply in the UK only.
Symbols
Safety instructions in this document
are identified by a warning-triangle sym-
bol and are printed on a grey back-
ground.
i
Notes containing important information
are identified by the symbol shown on the
left. They are bordered by horizontal lines
above and below the text.

6 720 610 597 GB (01.07)
4
Details of the appliance
1 Details of the appliance
1.1 EC Declaration of Conformity
This appliance is in accordance with the applicable
requirements of the Gas Appliance Directive, Boiler Effi-
ciency Directive, Electromagnetic Compatibility Direc-
tive and the Low Voltage Directive.
1.2 Standard package
• Gas condensing combination boiler for central
heating and domestic hot water
• Control panel cover
• Wall mounting frame
• Clamp for securing flue duct kit
• Fixings (screws etc.)
• Set of documentation for appliance
• Pre-plumbing manifold
• Condensate drain pipe
• Filling loop.
1.3 Description of appliance
• Wall-mounted appliance, siting not dependent on
room size
• Natural gas models are low-emission appliances
• Multifunction display
• Bosch Heatronic control system with integrated
textdisplay for servicefunctions and faults
• 3-channel - digital timer for one heating circuit
• variable pump
• Automatic ignition
• Modulating control
• Full safety systems incorporating Bosch Heatronic
with flame ionisation monitoring, solenoid valves and
temperature sensors
• Concentric flue/air duct with testing point for
CO
2
/CO
• Regulated speed fan
• Pre-mix burner
• Temperature control for central heating
• Temperature sensor in domestic hot water
• Safety temperature limiter in 24 V electrical circuit
• Relief valve, pressure gauge, expansion vessel
• Flue gas temperature limiter (105 °C)
• Hot water priority circuit
• Motorised 3-way valve
• Plate-type heat exchange
• Condensate Trap.
PIN CE-0085 BL0507
Category
UK II
2H 3P
Appliance Type C
13
, C
33
Table 1

6 720 610 597 GB (01.07)
Details of the appliance
5
1.4 Accessories
• Standard horizontal flue kit at 100 mm outside
diameter for flues upto 4 m in length.
• Flue duct kits for horizontal (125 mm outside
diameter) for flue lengths upto 10 m (ZWBR 11-35)
or 13 m (ZWBR 7-28) and vertical flue systems for
flue lengths 12 m (ZWBR 11-35) or 15m (ZWBR 7-
28). Fitting instructions are sent with these kits.
• Heating programmer
• Security kit.
1.5 Casing dimensions
Fig. 1
13 Manifold assembly
101 Outer case
103 Facia cover
X Standard Concentric Horizontal Flue System: min. 310 mm
Alternative Concentric Flue System: min. 250 mm
Y Standard Concentric Horizontal Flue System: 158 mm
Alternative Concentric Flue System: 121 mm
Z Standard Concentric Horizontal Flue System: 105 mm
Alternative Concentric Flue System: 130 mm
min.
100 min.
100
512
850
101
103
6 720 610 602 - 01.1O
200
30
13
395 250
360
861
906
35
X
120
Y
Z

6 720 610 597 GB (01.07)
6
Details of the appliance
1.6 Layout of appliance
Fig. 2
4 Heatronic control
6 Heat exchanger safety temperature limiter
6.1 Hot water NTC sensor
7 Testing point for gas supply pressure
8.1 Pressure gauge
9 Flue gas temperature limiter
15 Relief valve
18 Pump
20 Expansion vessel
27 Automatic air vent
29 Air gas Mixer unit
32.1 Electrode assembly
36 Temperature sensor in CH flow
43 CH flow
63 Adjustable gas flow restrictor
64 Adjusting screw for min. gas flow volume
88 3-way valve (combi)
98 DHW flow switch (combi)
102 Inspection window
120 Fixing points
221.1 Flue duct
221.2 Combustion air intake
226 Fan assembly
295 Appliance type sticker
234 Testing point for combustion products
234.1 Testing point for combustion air
271 Flue duct
349 Cover plate for twin flue duct connection
355 Plate-type domestic hot water heat exchanger
358 Condensate trap
396 Hose Condensate trap
400 Textdisplay
415 Cover plate for cleaning access
416 Condensate collector
418 Data plate
423 Siphon
29
98
102
226
234.1
271
416
221.1
221.2
20
43
9
63
358
64
7
355
6.1
4
415
6
36
32.1
234
349
295
8.1
18
27
88
15
120
418
400
396
423
6 720 610 597 - 02.1O

6 720 610 597 GB (01.07)
Details of the appliance
7
1.7 Function
Fig. 3
4Bosch Heatronic control
6Temperature limiter, heat exchanger
6.1 Hot water NTC sensor
7Testing point for gas supply pressure
8.1 Pressure gauge
9Flue gas temperature limiter
13 Manifold
15 Safety valve
18 Central heating pump
20 Expansion vessel
26 Charging valve
27 Automatic vent
29 Mixer unit
29.1 Bi-metallic thermostat for combustion air compensation
30 Burner
32 Flame sensing electrode
33 Igniter electrode
35 Heat exchanger with cooled combustion chamber
36 Temperature sensor in CH flow
43 CH flow
44 Hot water flow
45 Gas
46 Cold water inlet
47 CH return
52 Solenoid valve 1
52.1 Solenoid valve 2
55 Filter
56 Gas valve CE 427
57 Main valve disc
61 Reset button
63 Adjustable gas flow restrictor
64 Adjusting screw for min. gas flow volume
69 Control valve
84 Motor
88 3-way valve
90 Venturi
91 Pressure relief valve
93 Water flow regulator
94 Diaphragm
95 Pushrod with switch cam
96 Microswitch
97 Valve for hot water flow volume
98 Water valve
221 Flue duct
226 Fan
229 Air box
234 Testing point for flue gas
234.1 Testing point for combustion air
317 Display
355 Plate-type heat exchanger
358 Condensate trap
400 Textdisplay
423 Siphon
ϑ
33
29 30
226
229 234
234.1
26
6
36
29.1
63
15
45 47
20
43 44 46
13
8.1
84
90
97 98
93
94
95
96
91
69
64
57
52.1
56
52
55 7
355
M
358
18
88
max
max
1
2
345
E
ECO
0
317
61
4400
32
9
35
221
ϑ
27
6.1
6 720 610 597- 03.1O
423

6 720 610 597 GB (01.07)
8
Details of the appliance
1.8 Electrical wiring diagram
Fig. 4
4.1 Ignition transformer
6Temperature limiter, heat exchanger
6.1 Hot water NTC sensor
9Flue gas temperature limiter
18 Pump
32 Flame sensing electrode
33 Ignition electrode
36 Temperature sensor in CH flow
52 Solenoid valve 1
52.1 Solenoid valve 2
56 Gas valve CE 427
61 Reset button
84 Motor, 3-way valve
96 Microswitch, hydraulic switch
135 Master switch
136 Temperature control for CH flow
151 Fuse, slow 2.5 A, AC 230 V
153 Transformer
161 Link
226 Fan
300 Code plug
302 Earth connection
310 Temperature control for hot water
312 Fuse, slow T 1,6 A
313 Fuse, slow T 0,5 A
317 Digital display
328 Terminal block for AC 230 V Mains supply
328.1 Link
363 Indicator lamp for burner
364 Indicator lamp for power supply
365 “Chimney sweep” button
366 Service button
367 ECO button
400 Textdisplay
422 Connecting TR2
6
9
32
33
36
52.1
52
56
61
230 V
135
25 V
230V/AC
153 136
151 124789
161
M226
300
LNLsNs
328
LR
302
310
312
313
317 363
364 365 366
ECO
367
4.1
328.1
6.1
18
84
96
M
400
4
3F
M
6 720 610 602 - 02.1O
mains supply
422
o - orange g - green bl - black r - red p - purple
r
r
bl
bl
bl
bl bl
o
o
oog
g
p
p
p

6 720 610 597 GB (01.07)
Details of the appliance
9
1.9 Technical data
Units
ZWBR 7-28
Natural gas
ZWBR 11-28
Propane
ZWBR 11-35
Natural gas
ZWBR 14-35
Propane
Max. rated heat output net 40/30 °C central heating
Max. rated heat output net 50/30 °C central heating
Max. rated heat output net 80/60 °C central heating
kW
kW
kW
30.1
29.8
28.2
30.1
29.8
28.2
37.5
37.1
35.1
37.5
37.1
35.1
Max. rated heat input net kW 28.5 28.5 35.5 35.5
Min. rated heat output net 40/30 °C
Min. rated heat output net 50/30 °C
Min. rated heat output net 80/60 °C
kW
kW
kW
8.4
8.3
7.4
11.6
11.4
10.5
12.9
12.8
11.4
16.2
16.1
14.3
Min. rated heat input net kW 7.6 10.8 11.8 14.8
Max. rated heat output net, domestic hot water kW 28.2 28.2 35.1 35.1
Max. rated heat input net, domestic hot water kW 28.5 28.5 35.5 35.5
Maximum gas flow rate – After 10 minutes from lighting
Natural gas G20 (HiB = 9,5 kWh/m3)m
3/h 3.0 3.7
LPG (Hi= 12,8 kWh/kg) kg/h 2.2 2.5
Gas supply pressure
Natural gas G20 mbar 20 - 20 -
LPG mbar - 37 - 37
Expansion vessel
Charge pressure bar 0.75 0.75 0.75 0.75
Total capacity l 18 18 10 10
Hot water specifications
Hot water flow rate (factory setting) l/min 8 8 8 8
Max. hot water flow rate l/min 14 14 14 14
Outlet temperature range °C 40 - 60 40 - 60 40 - 60 40 - 60
Max. permissible water supply pressure bar 10 10 10 10
Min. inlet pressure bar 0.2 0.2 0.2 0.2
Specific flow rate l/min 13.7 13.7 16.0 16.0
Flue
Flue gas temp. 80/60 °C, rated/min. load °C 67/55 67/55 87/58 87/58
Flue gas temp. 40/30 °C, rated/min. load °C 43/32 43/32 65/43 65/43
Residual delivery pressure
(inc. pressure drop in air intake duct) Pa 80 80 100 100
CO2level at max. rated heat output
CO2level at min. rated heat output
%
%
9.5
9.2
11.3
11.0
9.2
9.2
11.0
11.0
NOx-class 5 5 5 5
SEDBUK figure, Band A % 90.6 90.6 90.3 90.3
Condensate
Max. condensation rate (tR= 30 °C) l/h 2.4 2.4 3.0 3.0
pH-value, approx. 4.8 4.8 4.8 4.8
General Data
Electrical power supply voltage AC ... V 230 230 230 230
Frequency Hz 50 50 50 50
Max. power consumption W 121 121 151 151
Noise output level dB(A) 37 37 40 340
Appliance protection rating IP X4D X4D X4D X4D
Max. CH flow temperature °C nom. 90 nom. 90 nom. 90 nom. 90
Max. permissible operating pressure (CH) bar 2.5 2.5 2.5 2.5
Permissible ambient temperatures °C 0 - 60 0 - 60 0 - 60 0 - 60
Nominal capacity of appliance l 3.75 3.75 3.75 3.75
Weight kg 53 53 53 53
Table 2

6 720 610 597 GB (01.07)
10
Details of the appliance
Condensate analysis, mg/l
Flue system
Elbow - 90 ° Bend - 45 °
Equivalent length 2 m Equivalent length 1m
Gas supply
Domestic water performance
Ammonium 1.2 Nickel 0.15
Lead ≤0.01 Mercury ≤0.0001
Cadmium ≤0.001 Sulphate 1
Chromium ≤0.005 Zinc ≤0.015
Halogenated
hydrocarbons ≤0.002
Tin ≤0.01
Hydrocarbons 0.015 Vanadium ≤0.001
Copper 0.028 pH-value 4.8
Table 3
HORIZONTAL 100 mm – Standard
Overall Diameter of Duct mm 100
Max. 4 m
Flue Terminal / Duct
Assembly Length
mm 750
Extension Duct Length mm 1000
Table 4
ALTERNATIVE HORIZONTAL 125 mm FLUE SYSTEM
Overall Diameter of Duct mm 125
Max. 13 m
(ZWBR 7-28)
Max. 10 m
(ZWBR 11-35)
including turret
Flue Terminal / Duct
Assembly
mm 550
Extension Duct Length -
Fixed
mm 200
Extension Duct Length -
Fixed
mm 450
Extension Duct Length -
Fixed
mm 950
Extension Duct Length -
Fixed
mm 1950
Extension Duct Length -
Telescopic
mm 265-
375
Extension Duct Length -
Adjustable (Cut to length)
mm 200
Table 5
VERTICAL 125 mm FLUE SYSTEM
Overall Diametter of Duct mm 125
Max. 15 m
(ZWBR 7-28)
Max. 12 m
(ZWBR 11-35)
Flue Terminal / Duct
Assembly
mm 1360
Extension Duct Length mm 200
Extension Duct Length -
Fixed
mm 450
Extension Duct Length -
Fixed
mm 950
Extension Duct Length -
Fixed
mm 1950
Extension Duct Length -
Telescopic
mm 265-
375
Extension Duct Length -
Adjustable (Cut to length)
mm 450
Table 6
Total length of gas supply pipe
(metres)
Pipe diameter
(mm)
369
Gas discharge rate (m3/h)
8.7 5.8 4.6 22
18.0 12.0 9.4 28
Table 7
ZWBR
7-28
ZWBR
11-35
Domestic
Water Flow
Rate l/min
Temperature
Rise
30 °C 13.7 17.0
Temperature
Rise
35 °C 11.7 14.6
Temperature
Rise
40 °C 10.3 12.8
Maximum Mains pressure bar 10.0 10.0
Minimum Mains pressure bar 0.2 0.2
Table 8

6 720 610 597 GB (01.07)
Installation regulations
11
2 Installation regulations
Gas Safety (Installation & Use) Regulations 1998: All
gas appliances must be installed by a competent per-
son. Failure to install correctly could lead to prosecu-
tion.
The manufacturers notes must not be taken, in any way,
as overriding statutory obligations.
The appliance must be installed in accordance with the
current IEE Wiring Regulations, local Building Regula-
tions, Building Standards (Scotland) (Consolidation),
bye-laws of the local Water Company, Health and
Safety Document 635 (Electricity at Work Regulations
1989) and any other local requirements.
Product Liability regulations indicate that, in certain cir-
cumstances, the installer can be held responsible, not
only for mistakes on his part but also for damage result-
ing from the use of faulty materials. We advise the
installer to avoid any risk by using only quality approved
branded fittings.
The relevant British Standards should be followed i.e.
• BS 6798: Specification for the installation of gas
fired hot water boilers of rated input not exceeding
60kW
• BS 5449: Central Heating for Domestic Premises
• BS 5546: Installation of gas hot water supplies for
domestic purposes
• BS 5440:1: Flues and ventilation for gas appliances
of rated input not exceeding 60kW (gross): Flues
• BS 5440:2: Flues and ventilation for gas appliances
of rated input not exceeding 60kW (gross): Air
Supply
• BS 6891: Installation of low pressure gas pipework
installations up to 28mm (R1).
• BS 7074:1: Code of practice for domestic heating
and hot water supply.
These instructions must be followed.
3 Installation
3.1 Important remarks
yAppliance should only be installed in sealed central
heating and hot water systems.
yTo avoid gas formation in the system, galvanised radi-
ators or pipes must not be used.
yIf a room thermostat is used: do not fit a thermostatic
radiator valve on the radiator in the primary room.
yThis appliance uses an automatically variable pump.
An auto-bypass must not be fitted.
yAdd a suitable anti-freeze fluid to the water in the
central heating system.
Suitable products are available from Betz-Dearborn
Tel.: [phone] and Fernox Tel.: 01799
550811.
yIn our experience, the addition of sealing agents to
the water in the central heating system can cause
problems (deposits in the heat exchanger). For that
reason we advise against their use.
yAlways turn off the gas cock before car-
rying out any work on components
which carry gas.
iFixing of the appliance, gas and flue con-
nections, commissioning of the system
and electrical connections may only be
carried out by competent persons author-
ised by CORGI.

6 720 610 597 GB (01.07)
12
Installation
3.2 Domestic hot water
Any regulations specified by the local water company
must be observed.
The final 600 mm of the mains cold water connection to
the applaince should be made in copper tube only.
The appliance is suitable for a mains supply having a
maximum pressure of 10 bar. A pressure reducing valve
must be fitted, if necessary.
The hot water outlet temperature is set to be capable of
achieving a maximum of 60 °C. The maximum tempera-
ture and the frequency of the recharge of the heat store
may be reset.
The maximum water flow rate is factory set at 10.3 l/min
(ZWBR 7-28), at 12.8 l/min (ZWBR 11-35) to give
temperature rise of 40 °C. If a higher rise is required
then the flow must be reduced at the tap and the dis-
charge temperature will rise up to the maximum set fig-
ure.
The temperature rise, upto the maximum set by the user,
is automatically maintained by the modulation of the
heat input. In winter, when the mains temperature is very
low, the water flow, adjusted at the tap or shower,
should be reduced to maintain the required delivery
temperature.
It is suggested that long pipe runs to taps or showers
be insulated to prevent the rapid cooling of the water.
All types of single lever mixer taps and thermostatic
mixer units suitable for a mains pressure of up to 10 bar
can be used.
The head of a loose-head shower must not be allowed
to fall within 25 mm of the top the bath to prevent the
risk of water being drawn back into the mains. Alterna-
tively the shower must be fitted with an anti-syphonage
device at the point of the flexible hose connections.
Over-rim bidets may be connected to the appliance pro-
vided that it is in accordance with the requirements of
the local water company. The outlet(s) should be
shrouded and unable to have any temporary hand held
spray attached. No anti-syphonage arrangements are
necessary.
In exceptionally hard water areas a device to prevent
scale formation may be fitted or, alternatively, the maxi-
mum temperature reset to about 45 °C which may
reduce the risk of scale formation. The installation of a
scale inhibitor assembly should be in accordance with
the requirements of the local water company. Artificially
softened water must not be used. An isolating valve
should be fitted to allow for servicing.
Devices, such as water meters or back-flow pre-
vention valves, capable of preventing the flow of
expansion water must not be fitted unless sepa-
rate arrangements have been made.
A Zilmet Z160 expansion vessel is the preferred type. A
thread sealant compatible with potable water must be
used.
3.3 Sealed systems
The appliance must not be operated without the system
being full of water, properly vented and pressurised.
The expansion vessel has a volume of 10 litres (ZWBR
11-35) or 18 litres (ZWBR 7-28) and is charged to a
pressure of 0.75 bar.
The water capacity of the system is shown in table 11,
page 32. If a greater capacity is required then an addi-
tional expansion vessel must be fitted into the system
return as close to the appliance as possible. The system
pressure can be set up to a maximum of 1.5 bar with
1 bar being the normal setting.
If the system pressure is greater than 2.5 bar when the
appliance is operating at maximum temperature then an
additional expansion vessel must be fitted into the sys-
tem return as close to the appliance as possible.
The filling point must be at low level and arranged as
shown in figs. 5 and 6.
The pressure relief valve is set to operate at 3 bar.
There must be no connection to the mains without the
approval of the local water company. All connections in
the system must be capable of withstanding a pressure
of up to 3 bar and the radiator valves conform to the
requirements of BS 2767:10.
If Thermostatic Radiator Valves are fitted then it is rec-
ommended that one radiator is left open.
Repeated venting probably indicates a leak and this
must be rectified to ensure the proper operation of the
appliance.
No galvanised radiators or pipes must be used.
If any system water treatment is required then
only products suitable for use with Aluminium
shall be used i.e Fernox- Copal or Sentinal X100,
in accordance with the manufacturers
instructions. The use of any other substances will
invalidate the guarantee. The pH value of the
system water must be less than 8 or the
appliance guarantee will be invalidated.
A drain cock to BS 2879 must be fitted to the lowest
point of the system.
IMPORTANT: Check that no dirt is left in the
water pipework as this could damage the
appliance. Thoroughly flush the heating system
and the mains water supply before fitting the
appliance to the wall in accordance with the
recommendations of BS7593:1992.

6 720 610 597 GB (01.07)
Installation
13
Fig. 5 Sealed primary water system
Fig. 6 Sealed primary water system - filling method
3.4 Siting the appliance
Regulations concerning the Installation Site
yRelevant national regulations must be complied with
section 3.9.1.
yConsult the installation instructions for details of min-
imum clearances required.
Combustion air
In order to prevent corrosion, the combustion air must
not contain any corrosive substances.
Substances classed as corrosion-promoting include
halogenated hydrocarbons which contain chlorine and
fluorine compounds and are contained in some sol-
vents, paints, adhesives, aerosol propellants and house-
hold cleaners, for example.
Surface temperature
The max. surface temperature of the casing and the flue
is less than 85 °C.
This means that, no special safety precautions are
required with regard to flammable building materials
and fitted furniture. The specified clearences must be
maintained.
Cupboard/Compartment
The appliance can be installed in a cupboard/compart-
ment need for airing clothes providing that the require-
ments of BS 6798 and BS 5440:2 are followed. The
low casing losses from the appliance eliminate the need
for ventilation openings in the compartment.
Domestic
hot water
Domestic
hot water
Central heating flow Radiator
valve
Lockshield
valve
Central heating return
A drain cock should be fitted at
the lowest point of the heating
circuit and the appliance
Water
main
BS stop valve.
Fixed spindle type
APPLIANCE
Refer to Fig.1
Appliance
water flow
diagram
WRC approved
filling loop
6 720 610 576 -09.1O
Heating
return Non-return
valve Non-return valve
Hose
union Hose union
Test
cock
Temporary hose
Test
cock
6 720 610 576 - 10.1O

6 720 610 597 GB (01.07)
14
Installation
3.5 Wall mounting frame assembly
yTake the wall mounting frame out of the package and
screw together with 6 screws as shown in fig. 7. Use
the outer lugs on the top and bottom horizontal sec-
tions for the appliances that are 512 mm wide.
Fig. 7
yHold the wall-mounting frame against the wall ensur-
ing that it is vertical.
yMark the postion of the flue duct hole if a rear flue is
to be used. Refer to fig. 1 and 15.
yMark the holes for the wall mounting frame onto the
wall, drill and plug the holes and screw the wall
mounting frame to the wall with the screws provided.
Fig. 8
yScrew the pre-plumbing manifold with two screws to
the wall mounting frame.
Fig. 9
3.6 Pre-piping the system
Fig. 10 Manifold
43 CH flow
47 CH return
112 Gas cock
171 Domestic hot water
172 Cold water relief
yA drain tap should be fitted at the lowest point of the
central heating system.
yWRc filling loop must be fitted.
6 720 610 597-06.1O
6 720 610 597-07.1O
6 720 610 597-08.1O
200
260
6 720 610 576-06.1O
35
120-130
50
4743 172112
171

6 720 610 597 GB (01.07)
Installation
15
Condensate drain
Prepare the condensate discharge system. Refer to
fig. 11. The condensate drainage pipe should be a
standard drain pipe material , i . e. PVC, PVC-U, ABS
etc. and should be at least 22 mm in diameter.
A siphon with a 75 mm condensate seal is fitted within
the appliance.
A connection to an internal drain is recommended.
Any external drain pipe should be insulated to prevent
freezing.
The connection of a condensate pipe to a drain may be
subject to local building regulations.
For more information refer to the CIBSE Guide,
BS5546 and the Building Regulations.
Fig. 11 Position of the condensate drain
3.7 Fitting the appliance
yRemove packing, taking care to observe the instruc-
tions on the packing.
yLie the boiler on its back.
Removing the outer case
yRemove retaining screw on right hand side (1.).
yPress both catch levers backwards (2.).
yLift off the top fixing lugs and slide case forwards and
remove (3.).
Fig. 12
Fixing the appliance
yFit the washers onto the gas and water connections.
yLift the boiler onto the wall-mounting frame. The lugs
pass through the rectangular holes in the boiler back
panel.
yTake care not to disturb the washers on the connec-
tions.
6 720 610 602 - 03.1O
Benchmark: For optimum performance
after installation, this boiler and its asso-
ciated central heating system must be
flushed in accordance with the guide-
lines given in BS5793:1992 “Treatment
of water in domestic hot water central
heating systems”.
iThe outer case is secured against unau-
thorised removal by one screw (electrical
safety) at the right side.
Always secure the outer case with this
screw again after refitting.
1.
2.
2.
6 720 610 336 10 1R
3.

6 720 610 597 GB (01.07)
16
Installation
Connecting the flue duct
yFit flue duct connector onto appliance flue spigot.
ySecure with the two screws supplied.
Fig. 13
yFor remaining installation of flue assembly, refer to
the relevant installation instructions.
3.8 Checking the connections
Water connections
yCheck that the O-rings or seals are in place before
tightening the connection.
yTurn on the service valves for central heating flow
and return and fill the heating system through a WRC
approved filling loop.
yCheck all seals and unions for leaks (testing pressure
max. 3.0 bar as indicated by pressure gauge).
yTurn on cold water service cock and fill hot water sys-
tem (testing pressure max. 10 bar).
yCheck all connections for leaks.
Gas supply pipe
yCheck that the seal is in place before tightening the
connection.
yTurn off gas cock to protect gas valve against
damage from excessive pressure.
yCheck gas supply pipe.
yRelease the pressure on the gas supply pipe.
3.9 Flue Systems
The only flue systems that may be used are those sup-
plied by Worcester Heat Systems.
The flue system must be installed in accordance with
the requirements of BS5440:1.
Standard 100 mm flue system
The standard concentric flue system provides for a hor-
izontal length of upto 4 m. Full instructions for fitting this
flue are in Subsection 3.9.2 “Installation of the flue”.
Alternative 125 mm diameter flue systems
Installation instructions for the alternative flue systems
are sent with the appropriate flue kit.
Systems are available to give a maximum horizontal
length of 13 m (ZWBR 7-28) and 10 m (ZWBR 11-35).
A vertical flue system upto a height of 15 m (ZWBR 7-
28) and 12 m (ZWBR 11-35) is available.
45° and 90° flue bends can be used with a correspond-
ing reduction in flue length of 2 m for each 90° bend
and 1 m for each 45° bend used.
IMPORTANT: Any horizontal flue system fitted to a
condensing boiler must incline towards the appliance at
an angle of 3 % (30 mm per metre length) to prevent
condensate dripping from the flue terminal. This
means that the clearance above the appliance
must be increased to match the duct length.
Refer to fig. 1 on page 5.
6 720 610 332-09.1R
1
3
2
4

6 720 610 597 GB (01.07)
Installation
17
3.9.1 Siting the Flue Terminal
The flue must be installed in accordance with
BS 5440:1 and the Building Regulations. Flue terminals
in carports and under balconies are to be avoided.
The terminal must be positioned so that it does not
cause an obstruction nor the combustion products a
nuisance. See fig. 14 and table 9.
The terminal will, at times, give out a plume of water
vapour and consideration must be given to this when
choosing a terminal position. Keep clear of security
lighting, activated by passive infra-red sensing heads.
If the terminal is less than 2 m above a surface to which
people have access then a guard must be fitted. The
guard must be evenly spaced about the terminal with a
space of 50 mm in each direction and fixed with plated
screws.
A guard Type K2 for the standard horizontal flue, can be
obtained from Tower Flue Components, Vale Rise, Ton-
bridge TN9 1TB.
Fig. 14
Minimum dimensions of flue terminal positions (all types) (see fig. 14)
Dimension Terminal Position (kW input expressed in net) Balanced flues room sealed: Fanned draught
A1) Directly below an opening, air brick, opening windows, etc. 300 mm
B 1) Above an opening, air brick, opening window, etc. 300 mm
C 1) Horizontally to an opening, air brick, opening window, etc. 300 mm
D Below gutters, soil pipes or drain pipes 75 mm
E Below eaves 200 mm
F Below balconies or car port roof 200 mm
G From a vertical drain pipe or soil pipe 150 mm
H From an internal or external corner 300 mm
I Above ground roof or balcony level 300 mm
J From a surface facing the terminal 600 mm
K From a terminal facing the terminal 1200 mm
L From an opening in the car port (e. g. door, window) into the dwelling 1200 mm
M Vertically from a terminal on the same wall 1500mm
N Horizontally from a terminal on the same wall 300 mm
O From the wall on which the terminal is mounted Not applicable
P From a vertical structure on the roof Not applicable
Q Above intersection with roof Not applicable
Table 9
1) In addition, the terminal should not be nearer than 150 mm (fanned draught) to an opening in the building fabric formed for the pur-
pose of accommodating a built-in element such as a window frame.

6 720 610 597 GB (01.07)
18
Installation
3.9.2 Installation of the flue
The standard 100 mm diameter horizontal flue system is
suitable for lengths upto 4 m.
Flues upto 650 mm do not require an extension duct
assembly.
Flues between 1600 mm and 4000 mm require exten-
sion duct assemblies.
NOTE: Flue lengths between 650 mm and 730 mm
cannot be accomodated. Refer to fig. 16, 17, 18.
Standard system comprise: Flue turret - Flue turret
clamp - Terminal assembly - Wall sealing - plates.
Extension kit comprises: Air duct - Flue duct - Duct
clamp. Refer to fig. 19.
Instructions for fitting other flue systems are packed
with the relevant flue kit.
Check that the position chosen for the appliance is sat-
isfactory Refer to fig. 15.
Fig. 15 Marking the position of the side flue opening
Fig. 16 Standard Flue
Appliance
120
Drilling point for
flue duct opening
3 %
(30 mm/meter)
Centre
line of
flue
opening
and
appliance
Centre line of
flue/air duct
Top of the
wall
mounting
frame
H
H
Standard Horizontal Flue 158 mm
Optional Horizontal Flue 121 mm 6 720 610 602 - 07.1O
Flue
Turret
No
Clamp
Maximum 650 mm
Terminal
Assembly
Outer
Wall
6 720 610 602 - 08.1O

6 720 610 597 GB (01.07)
Installation
19
Fig. 17 Flue with one extension
Fig. 18 Flue with extensions
Fig. 19 Flue components
Maximum 1600mm
Flue
Turret
No
Clamp
Terminal
Assembly
Outer
Wall
Extension
Duct
6 720 610 602 - 09.1O
Clamp
Flue
Turret
No
Clamp Clamp
Extension
Duct
Clamp
Extension
Duct
Terminal
Assembly
Outer
Wall
6 720 610 602 - 10.1O
Extension Air Duct
Extension Flue Duct
Terminal Assembly
Duct Clamp
Wall Sealing Plates
6 720 610 602 - 11.1O
Flue
Turret

6 720 610 597 GB (01.07)
20
Installation
3.9.3 Flue duct preparation and assembly
Measure the flue length L. Refer to fig. 20, 21.
Fig. 20 Flue length - rear
Fig. 21 Flue length - side
Mark off the lengths shown onto the ducts and cut to
length. The cuts must be square and free from burrs.
Terminal assembly outer (air) duct - L-750 mm, inner
(flue) duct - L- 50 mm.The measurement is made from
the ridge at the terminal indicating the outer face of the
wall. Refer to fig. 22.
Extension air duct - L-70mm, flue duct - L-50 mm.
The measurement is from the formed end.
Fig. 22 Flue terminal position
Assemble flue system completely. Push the ducts fully
together and clamp in the positions. The slope of the
terminal outlet must face downwards.
The assembly will be made easier if a solvent free
grease is lightly applied i.e Vaseline, to the male end of
the ducts.
NOTE: An inner wall sealing plate is provided
which should be fitted to the ducts before assem-
bly.
Push the assembly through the wall and fix the turret to
the appliance with the clamp. Refer to fig. 23.
Fig. 23
Ensure that the turret is fully entered into the socket on
the boiler. From the outside fix the outer wall plate to the
terminal and, after ensuring the duct is properly i nclined
towards the boiler, fix the plate to the wall.
If the terminal is within 2 m of the ground where there is
access then an approved terminal guard must be fitted.
The guard must give a clearance of at least 50 mm
around the terminal an be fixed with corrosion resistant
screws.
NOTE: THE FLUE MUST BE INCLINED TO THE
BOILER
L
120
6 720 610 602 - 12.1O
NOTE: THE FLUE MUST BE INCLINED TO THE
BOILER
L
6 720 610 602 - 13.1O
Outer
Wall
Face Flue Terminal
Raised Ring
locating the
terminal relative
to the outside
wall face
6 720 610 576 - 20.1O
Air and
Flue Duct
Entry into
silicone
rubber seals
Flue Turret
Clamp
Flue Socket
on Boiler 6 720 610 602 - 14.1O