Worcester benchmark ZWB 7-25 R 25 HE User guide

Installation and Servicing Instructions
R 25 & 30 HE combi
Wall mounted condensing boiler for central heating and mains
fed domestic hot water
6720 610 577-01.10
ZWB 7-25 R 25 GC-Number: 47 311 77
ZWB 7-30 R 30 GC-Number: 47 311 78
6 720 611 441GB (03.11) TD

6 720 611 441 GB (03.11)
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 12
3.1 Important remarks 12
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 19
4 Electrical connections 21
4.1 Connecting the appliance 21
4.2 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 Individual settings 27
6.1 Mechanical settings 27
6.1.1 Checking the size of the expansion vessel 27
6.1.2 Setting the central heating flow temperature 27
6.1.3 Changing the heating pump characteristic 27
6.2 Settings on the Bosch Heatronic 28
6.2.1 Operating the Bosch Heatronic 28
6.2.2 Setting the anti-cycle time
(Service Function 2.4) 28
6.2.3 Setting the maximum CH flow temperature
(Service Function 2.5) 28
6.2.4 Setting the switching difference
(Service Function 2.6) 28
6.2.5 Setting the heating output
(Service Function 5.0) 28
6.2.6 Constant hot water cycle time
(Service Function 6.8) 29
6.3 Setting the gas/air ratio 29
7 Converting the appliance to different gas
types 30
7.1 Setting the gas/air ratio 30
7.2 Testing combustion air/flue gas at set heat out-
put 32
7.2.1 Testing the O2 or CO2 level in the combustion
air 32
7.2.2 Testing CO and CO2 32
8 Maintenance 33
8.1 Pre-Service Check List 34
8.2 Description of servicing operations 35
8.3 Replacement of Parts 38
8.3.1 PCB control board and transformer 38
8.3.2 Fan Assembly 39
8.3.3 Pump 39
8.3.4 Diverter valve 40
8.3.5 Diverter valve motor 40
8.3.6 Sensors 40
8.3.7 Gas Valve 41
8.3.8 Domestic Hot Water Heat Exchanger 41
8.3.9 Electrode assembly 41
8.3.10Pressure gauge 41
8.3.11Expansion vessel 41
8.3.12Pressure Relief Valve 41
8.3.13Burner 41
8.3.14Flow switch 42
8.3.15Primary Heat Exchanger 42
9 Appendix 43
9.1 Fault Codes 43
9.2 Short parts list 44
9.3 Heating/hot water output settings (N.G) 45
9.4 Heating/hot water output settings (L.P.G) 45
9.5 Operational Flow diagrams 46
9.5.1 Domestic hot water function 46
9.5.2 Central heating function 47

6 720 611 441 GB (03.11)
Safety precautions
3
Safety precautions
If you smell gas
BTurn off gas service cock at the meter.
BOpen windows and doors.
BDo not operate any electrical switches.
BExtinguish any naked flames.
BTelephone your gas company.
If you smell fumes from the appliance
BSwitch off appliance (see page 24).
BOpen windows and doors.
Fitting and modifications
BFitting of the appliance or any controls to the appli-
ance may only be carried out by a competent engi-
neer in accordance with the Gas Safety (Installation
and Use) Regulations 1998.
BFlue systems must not be modified in any ways other
than as described in the fitting instructions.
BThis appliance is for use on sealed primary systems only.
Maintenance
BThe user is recommended: to have the system
regularly serviced in order to ensure that it functions
reliably and safely.
BUse only original spare parts!
Combustible materials
BDo not store or use any combustible materials
(paper, thinners, paints etc.) in the vicinity of the
appliance.
Health and safety
BThis appliance contains no asbestos products.
BThere is no potential hazard due to the appliance
being electrically unsafe.
BThere 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
BThe 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
BExplain to the customer how the appliance works and
how to operate it.
BAdvise the user that he/she must not make any modi-
fications to the appliance or carry out any repairs on it.
BThese instructions are to be left with the user or at
the Gas meter.
BImportant: These instructions apply in the UK only.
Unpacking
IMPORTANT HANDLING INSTRUCTIONS
BTwo people should transfer the packaged appliance
from the van to the point of installation
BOpen the top of the carton, remove and place the
component tray and both side bars of the wall mount-
ing frame to one side
BLie the packaged appliance on its back. (The back
has “TRUCK HERE” printed on the carton)
BOne person firmly holds the packaging while the
other straddles the boiler and slides it from the pack-
aging
BTwo persons are then required to lift one end and
stand the appliance upright with the flue at the top
Additional requirements for roof space instal-
lation
BTwo people should use two step ladders and share
lifting the unpacked boiler up to the loft hatch
BWhere the boiler enters the loft space, tilt and slide
the boiler on its back to the point of installation
Check the contents against the packing list.
Symbols
Safety instructions in this document
are identified by a warning-triangle sym-
bol and are printed on a grey back-
ground.
iNotes containing important information
are identified by the symbol shown on the
left. They are bordered by horizontal lines
above and below the text.

6 720 611 441 GB (03.11)
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 heat-
ing and domestic hot water
• Wall mounting frame
• Fixings (screws etc.)
• Set of documentation for appliance
• Pre-plumbing manifold
• Condensate drain pipe.
1.3 Description of appliance
• Wall-mounted appliance, siting not dependent on
room size
• Natural gas models are low-emission appliances
• Multi function display
• Bosch Heatronic control system
• 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
CO2/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
• Three-speed central heating pump with automatic
vent
• 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 BL 0507
Category
UK II2H 3P
Appliance Type C13, C33
Table 1

6 720 611 441 GB (03.11)
Details of the appliance
5
1.4 Accessories
• Standard horizontal flue kit at 100 mm outside
diameter for flues up to 4 m in length.
• Flue duct kits for horizontal (125 mm outside
diameter) for flue lengths up to 13 m and vertical flue
systems for flue lengths up to 13.7 m. Fitting instruc-
tions are sent with these kits.
• Heating programmers
• Single or Twin channel digital timer
• Single channel mechanical timer
• RF controlled Digistat
• Night Set Back module
• TR2 room controllers.
NOTE: Where a timer, other than the Twin Channel Dig-
ital, is used, the Hot Water Pre-Heat facility can only be
isolated with the ECO button on the fascia.
1.5 Casing dimensions
Fig. 1
13 Manifold assembly
101 Outer case
103 Facia cover
XStandard Concentric Horizontal Flue System: min. 160 mm
Alternative Concentric Flue System: min. 220 mm
YStandard Concentric Horizontal Flue System: 40mm
Alternative Concentric Flue System: 70 mm
ZStandard Concentric Horizontal Flue System: 105 mm
Alternative Concentric Flue System: 130 mm
* For servicing the appliance
Note: Horizontal flue only: dimension X may need to increase due
to the incline of the flue.
X
Y
120
600
Z
*
*
10*
850
440
395
200
360
850
30
6 720 610 601- 01.4O
101
103
35
13
200
min
10*
min

6 720 611 441 GB (03.11)
6
Details of the appliance
1.6 Layout of appliance
Fig. 2
4Heatronic control
6Heat exchanger safety temperature limiter
6.1 Hot water NTC sensor
7Testing point for gas supply pressure
8.1 Pressure gauge
9Flue gas temperature limiter
15 Relief valve
18 Pump
18.1 Pump speed selector switch
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
271 Flue duct
355 Plate-type domestic hot water heat exchanger
358 Condensate trap
415 Cover plate for cleaning access
416 Condensate collector
417 Clip for fixing outer case
418 Data plate
423 Siphon
6 720 610 599-00.TD
18.1
423
27
8.1
29
102
226
271
416
20
43
9
63
358
64
7
355
6.1
417
15
4
18
415
6
36
32.1
120
418
295
88
88
221.1
221.2

6 720 611 441 GB (03.11)
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 inlet
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 inlet 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 Inner casing
317 Display
355 Plate-type heat exchanger
358 Condensate trap
422 Digital timer
423 Siphon
443 Diaphragm
ϑ
33
29 30
32
226
229
9
35
221
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
66.1
52.1
56
52
55
7
ϑ
6.1
M
317
61
4
max
max
1
2
34
5
E
ECO
0
358
18
88
355
423
6 720 610 599-08.2O
27
443

6 720 611 441 GB (03.11)
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
314 Connector for programmer
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
6
9
32
33
36
52.1
52
56
61
230 V
135
25 V
230V/
A
C
153
136
151 124789
161
M
226
300
LNLs
Ns
328
LR
302
310
312
313
314
317
318
363
364 365 366
ECO
367
4.1
328.1
M
6.1
18
96
84
M
6 720 610 599-07.2O
mains supply
r
r
b
l
b
l
b
l
b
l
b
l
o
oo
o
g
p
p
p
g
o - orange g - green bl - black r - red p - purple

6 720 611 441 GB (03.11)
Details of the appliance
9
1.9 Technical data
Units
25 HE
Natural gas
25 HE
Propane
30 HE
Natural gas
30 HE
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
29.1
28.8
27.2
29.1
28.8
27.2
31.2 31.2
30.9 30.9
29.2 29.2
Max. rated heat input net kW 27.5 27.5 29.5 29.5
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
8.4 11.6
8.3 11.4
7.4 10.5
Min. rated heat input net kW 7.6 10.8 7.6 10.8
Max. rated heat output net, domestic hot water kW 27.2 27.2 29.2 29.2
Max. rated heat input net, domestic hot water kW 27.5 27.5 29.5 29.5
Maximum gas flow rate – After 10 minutes from lighting
Natural gas G20 (CVnet 34.02 MJ/m3)m
3/h 2.9 3.1
LPG (CVnet 88 MJ/m3)kg/h2.02.3
Gas supply pressure
Natural gas G20 (CVnet 34.02 MJ/m3)mbar20-20
LPG (CVnet 88 MJ/m3)mbar3737
Expansion vessel
Charge pressure bar 0.75 0.75 0.75 0.75
Total capacity l 10 10 10 10
Hot water specifications
Hot water flow rate @ 35°C l/min 10.24 10.24 13.3 13.3
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 for max. flow rate bar 1.2 1.2 1.2 1.2
Specific flow rate l/min 12.4 12.4 13.3 13.3
Flue
Flue gas temp. 80/60°C, rated/min. load °C 67/55 67/55 67/55 67/55
Flue gas temp. 40/30°C, rated/min. load °C 43/32 43/32 43/32 43/32
Residual delivery pressure
(inc. pressure drop in air intake duct) Pa 80 80 80 80
CO2level at max. rated heat output
CO2level at min. rated heat output
%
%
9.2
8.8
10.8
10.5
9.2
8.8
10.8
10.5
NOx-class 5555
SEDBUK figure Band A A A A
Condensate
Max. condensation rate (tR= 30°C) l/h 2.3 2.3 2.5 2.5
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 102 102 107 107
Noise output level dB(A) 36 36 37 37
Appliance protection rating with blanking plate fitted 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 - 50 0 - 50 0 - 50 0 - 502
Nominal capacity of appliance l 3.75 3.75 3.75 3.75
Weight (excluding packaging) kg 46 46 46 46
Table 2

6 720 611 441 GB (03.11)
10
Details of the appliance
Condensate analysis, mg/l
Flue system
Elbow - 90 ° Equivalent length 2 m
Bend - 45 ° 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 FLUE SYSTEM
Overall Diameter of Duct mm 100
Max.
4m
Flue Terminal / Duct
Assembly Length
mm 600
Extension Duct Length mm 1000
Table 4
HORIZONTAL 125 mm FLUE SYSTEM
Overall Diameter of
Duct
mm 125 Max. 13 m
(including
turret)
Flue Terminal / Duct
Assembly
mm 1030
Table 5
VERTICAL 100 mm FLUE SYSTEM
Overall Diameter of Duct mm 100 Max.
13.7m
(Excl.
Terminal)
Flue Terminal / Duct
Assembly
mm 1140
Table 6
VERTICAL 125 mm FLUE SYSTEM
Overall Diameter of Duct mm 125 Max. 5m
(Excl.
Terminal)
Flue Terminal / Duct
Assembly
mm 1365
Table 7
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 8
R25HE R30HE
Domestic
Water Flow
Rate l/min
Temperature
Rise 30 °C 11.9 15.6
Temperature
Rise 35 °C 10.2 13.3
Temperature
Rise 40 °C 8.9 11.7
Maximum Mains pressure bar 10.0 10.0
Minimum Mains pressure bar 0.2 0.2
Table 9

6 720 611 441 GB (03.11)
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 70 kW (net): Flues
• BS 5440:2: Flues and ventilation for gas appliances
of rated input not exceeding 70 kW (net): 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
• BS 7671: Requirements for Electrical Installation.
These instructions must be followed.

6 720 611 441 GB (03.11)
12
Installation
3 Installation
3.1 Important remarks
BAppliance should only be installed in sealed central
heating systems.
BTo avoid gas formation in the system, galvanised radi-
ators or pipes must not be used.
BIf a room thermostat is used: do not fit a thermostatic
radiator valve on the radiator in the primary room.
BAdd a suitable anti-freeze fluid compatible with alu-
minium to the water in the central heating system.
Suitable products are available from Betz-Dearborn
Tel.: [phone] and Fernox Tel.: 01799
550811.
BIn 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.
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 appliance 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.
A water flow rate of 11.7 l/min will give a temperature
rise of 40°C. If a higher rise is required then the flow
must be reduced at the tap and the discharge tempera-
ture will rise up to the maximum set figure.
The temperature rise, up to 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 to fill the central heat-
ing system. 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. The vessel should be connected into the cold
water mains inlet pipe as close as possible to the appli-
ance.
Fig. 5
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 and is
charged to a pressure of 0.75 bar.
BAlways 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.

6 720 611 441 GB (03.11)
Installation
13
The water capacity of the system is shown in table 12,
page 27. 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.
Fig. 6 Sealed primary water system
If the system pressure is greater than 2.65 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. 6 and 5.
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.
Fit Thermostatic Radiator Valves to radiators in the
sleeping accommodation and not to the radiator where
the room thermostat is sited, this must be 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
use only products suitable for use with Alumin-
ium shall be used i.e Fernox- Copal or Supercon-
centrate 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.
Suitable products are available from Betz-Dearborn
Tel.: [phone] and Fernox Tel.: [phone]
A drain cock to BS2879 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 appli-
ance. Thoroughly flush the heating system and
the mains water supply before fitting the appli-
ance to the wall in accordance with the recom-
mendations of BS7593:1992.
3.4 Siting the appliance
Regulations concerning the Installation Site
BRelevant national regulations must be complied with
section 3.9.1.
BConsult 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 clearances 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 BS6798 and BS5440:2 are followed. The low
casing losses from the appliance eliminate the need for
ventilation openings in the compartment.
6 720 610 576 -09.3O
APPLIANCE
A drain cock should be fitted at the lowest point of the
heating circuit and the appliance
WRC
approved
filling loop
Domestic
hot water
BS stop valve
Fixed spindle type.
Water main
Refer to
Appliance
Water Flow
Diagram Lockshield valve
Radiator valve
Central heating return
Central heating flow

6 720 611 441 GB (03.11)
14
Installation
3.5 Wall mounting frame assembly
BTake the wall mounting frame out of the package and
screw together with 6 screws as shown in fig. 7. Use
the inner lugs on the top and bottom horizontal sec-
tions.
Fig. 7
BHold the wall-mounting frame against the wall ensur-
ing that it is vertical.
BMark the holes for the wall mounting frame onto the
wall, drill and plug the holes and fix the wall mounting
frame to the wall with the screws provided.
BMark the position of the flue duct hole if a rear flue is
to be used. Refer to fig. 1 and 16.
Fig. 8
BScrew 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 inlet
BA drain tap should be fitted at the lowest point of the
central heating system.
BWRAS approved filling loop must be fitted.
6 720 610 576-04.1O
6 720 610 576-05.1O
6 720 610 576-11.1O
200
260
6 720 610 576-06.1O
35
120-130
50
4743 172112
171

6 720 611 441 GB (03.11)
Installation
15
Condensate Termination and Route
The appliance has a built-in syphonic condensate trap
eliminating the need for external traps. Connect to the
22mm plastic drain pipe and extend the pipe run away
from the control panel and appliance with a constant fall
of 2.5 ° or 25 mm in every metre. See Fig. 12
The condensate pipe can terminate into any of four
areas:
Fig. 11
Whilst all of the above methods are acceptable it is
always the best practice to terminate the condense pipe
via an internal waste system.This will eliminate the need
for any external condensate pipe runs which can be sus-
ceptible to freezing in extreme weather.
Fig. 12 Recommended route of the condensate drain
External condensate pipework
The syphonic condensate trap collects condensate into
a trap which releases it in 100 ml quantities. This helps
to prevent the discharge from freezing.
If there is no alternative and the condensate pipe has to
be externally run, the following should be considered:
• The pipe run should take the shortest practical route.
• The pipework should be insulated with weather
resistant insulation.
• The pipe should terminate as close as possible to the
ground or drain, whilst still allowing the condensate
to safely disperse. This would prevent wind blowing
up the pipe.
• The pipework should be installed with the minimum
of horizontal runs and with a downward slope of at
least 2.5 °.
3.7 Fitting the appliance
Removing the outer case
BRemove retaining screws (1).
BSlide the outer case upwards and then forwards to
remove (2).
BRemove the wall mounting frame manifold kit and the
flue duct connector from the boiler
BRemove the plastic caps from the boiler connections.
Fig. 13
Boiler
Boiler
Sink
Ø 22 min.
Ø 22 min.
Ø 22 min.
Ø 22 min.
Siphon
Siphon
75 min. trap
Invert
No length
restriction
No length
restriction
No length
restriction
Internal soil
and vent stack
The gradient of the discharge pipe
should be 2.5¡ (40 mm/m) minimum
The gradient of the discharge pipe
should be 2.5¡ (40 mm/m) minimum
The gradient of the discharge pipe
should be 2.5¡ (40 mm/m) minimum
An internal waste system An external waste system
The rainwater system An external purpose made soakaway
The gradient of the discharge pipe should be
2.5¡ (40 mm/m) minimum
Use waterproof pipe work
insulation in very exposed
positions
Open end of pipe
direct into gully,
below ground but
above water level.
Open end of pipe
direct into gully,
below ground but
above water level
Open end of pipe direct
into gully, below ground
but above water level
75 min. trap
450 min.
Siphon
75 min. trap
Boiler
6 720 610 596 -03.2TD
Boiler
Sink
6 720 610 602 - 04.1O
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 two screws (electrical
safety).Always secure the outer case with
those screws again after refitting.
1
2

6 720 611 441 GB (03.11)
16
Installation
Fixing the appliance
BFit the washers onto the gas and water connections.
BLift the boiler onto the wall-mounting frame. The lugs
pass through the rectangular holes in the boiler back
panel.
BTake care not to disturb the washers on the connec-
tions.
Connecting the flue duct
BFit flue duct connector onto appliance flue spigot.
BSecure with screws supplied.
Fig. 14
BFor remaining installation of flue assembly, refer to
the relevant installation instructions.
3.8 Checking the connections
Water connections
BCheck that the O-rings or seals are in place before
tightening the connection.
BTurn on the service valves for central heating flow
and return and fill the heating system through a
WRAS approved filling loop.
BCheck all seals and unions for leaks (testing pressure
max. 3.0 bar as indicated by pressure gauge).
BTurn on cold water service cock and fill hot water sys-
tem (testing pressure max. 10 bar).
BCheck all connections for leaks.
Gas supply pipe
BCheck that the seal is in place before tightening the
connection.
BTurn off gas cock to protect gas valve against dam-
age from excessive pressure.
BCheck gas supply pipe.
BRelease the pressure on the gas supply pipe.
3.9 Flue Systems
The only flue systems that may be used are those sup-
plied with the boiler.
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 up to 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.
A vertical flue system up to a height of 13.7 metres is
available.
45° and 90° flue bends can be used with a correspond-
ing reduction in flue length of 2m for each 90° bend and
1 m for each 45° bend used.
IMPORTANT: Any horizontal flue system fitted to a
condensing boiler must incline from the appliance at an
angle of 3° (30 mm per metre length) to prevent con-
densate dripping from the flue terminal.
Note, the standard 100mm horizontal flue requires only
a 0.5° incline from the boiler as the inner exhaust pipe is
inclined at 2.5° inside the outer pipe.
This means that the clearance above the appli-
ance must be increased to match the duct length.
Refer to fig. 1 on page 5.
Retaining
Screw Flue Turret to
Boiler Sealing
Gasket
Flue Turret
6 720 610 599 - 01.TD
Appliance
Flue Socket
Flue seal

6 720 611 441 GB (03.11)
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. 15 and table 10.
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 K6 for the standard horizontal flue, can be
obtained from Tower Flue Components, Vale Rise, Ton-
bridge TN9 1TB.
Fig. 15
Minimum dimensions of flue terminal positions
(all types) (see fig 15. 15)
Q
QD,E
M
N
B
C
G
H
L
I
I
boundary
Q
K
H
H
A
F
J
P
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
B1) Above an opening, air brick, opening window, etc. 300 mm
C1) Horizontally to an opening, air brick, opening window, etc. 300 mm
D Below gutters, soil pipes or drain pipes 75 mm
E Below eaves 200 mm
F Below balconies or car port roof (lowest point) Not recommended
G From a vertical drain pipe or soil pipe 75 mm
H From an internal or external corner or to a boundary alongside the terminal 300 mm
I Above ground roof or balcony level 300 mm
J From a surface or boundary facing the terminal 1200 mm
K From a terminal facing the terminal 2000 mm
L From an opening in the car port (e. g. door, window) into the dwelling Not recommended
M Vertically from a terminal on the same wall 1500mm
N Horizontally from a terminal on the same wall 300 mm
P From a vertical structure on the roof 500 mm
Q Above intersection with roof 300 mm
Table 10
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.

6 720 611 441 GB (03.11)
18
Installation
3.9.2 Installation of the flue
The standard 100 mm diameter horizontal flue system is
suitable for lengths up to 4 m.
Flues up to 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 accommodated. Refer to Fig. 17, 18, 19.
Standard 100mm system comprise:
• Flue turret
• Flue turret clamp
• Terminal assembly
• Wall sealing gasket and cover plate.
Refer to Fig. 20.
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. 16.
Fig. 16 Marking the position of a side flue opening.
Note: ensure there is adequate access to the
air/flue sampling points in the flue turret.
Fig. 17 Standard Flue
Centre line of
flue/air duct
Centre
line of
flue
opening
and
appliance Drilling
point for
flue duct
opening
H= 40mm for the Standard 100mm Horizontal Flue
H= 70mm for the Optional 125mm Horizontal Flue
3°
(30mm/metre)
Standard 100mm
horizontal flue 0.5°
(5mm/metre)
Top of wall
mounting
frame (not
boiler)
Appliance
H
120mm
6 720 610 602-08.3O
Maximum 650mm
Clamp
Flue
Turret
Terminal
Assembly
Outer
Wall
6 720 610 599 - 01.TD
Minimum 100mm

6 720 611 441 GB (03.11)
Installation
19
Fig. 18 Flue with one extension
Fig. 19 Flue with extensions
Fig. 20 Flue components
3.9.3 Flue duct preparation and assembly
Measure the flue length L. Refer to fig. 21, 22.
Maximum 1600mm
Clamp
Flue
Turret
Terminal
Assembly
Outer
Wa ll
6 720 610 599 - 00.TD
Extension
Duct
Clamp
Flue
Turret
Terminal
Assembly
Outer
Wall
6 720 610 599 - 01.TD
Extension
Duct
Extension
Duct ClampClamp
Clamp
Flue
Turret
Extension Flue Duct
Flue Terminal Wall Sealing Gasket
6 720 610 599 - 01.TD

6 720 611 441 GB (03.11)
20
Installation
Fig. 21 Flue length - rear
Fig. 22 Flue length - side
Measure ‘L’ from the end of the metal section of the flue
terminal to the centre of the flue outlet on the boiler as
shown in Fig. 21 & Fig. 22 and deduct 90mm from that
measurement.
Cut both inner and outer flue pipe square at the oppo-
site end to the terminal without creasing the tubes.
Remove any burrs before fitting the terminal to the tur-
ret.
Fig. 23 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 Silicone lubricant, 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 screws provided. Refer to fig.
24.
Fig. 24 Flue turret
Ensure that the turret is fully secured to the socket on
the boiler.
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 and fixed with corrosion resistant
screws.
L
120
6 720 610 599 - 01.TD
L
6 720 610 599 - 01.TD
6 720 610 599-00.TD
Outer Wall Face
Flue Terminal
Wall Sealing Gasket
Retaining
Screw Flue Turret to
Boiler Sealing
Gasket
Flue Turret
6 720 610 599 - 01.TD
Appliance
Flue Socket
Flue seal