VOKERA Compact HE Release note

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Installation
& Servicing
Instructions
THESE INSTRUCTIONS
TO BE RETAINED
BY USER
Vokèra is a licensed member of the Benchmark scheme
which aims to improve the standards of installation and
commissioning of domestic hot water systems in the UK.
Compact HE
High efficiency combi boiler

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45
Contents
Designprinciplesandoperating sequence Page
1.1 Principlecomponents 2
1.2 Mode ofoperation (atrest) 2
1.3 Modeofoperation(heating) 2
1.4 Mode ofoperation (DHW) 2
1.5 Safety devices 2
Technicaldata Page
2.1 Centralheating 3
2.2 Domestic hotwater 3
2.3 Gas pressure 3
2.4 Expansionvessel 3
2.5 Dimensions 3
2.6 Clearances 3
2.7 Connections 3
2.8 Electrical 3
2.9 Fluedetails 3
2.10 Efficiency 3
2.11 Pumpduty 4
2.12 Appliance 4
Generalrequirements(UK) Page
3.1 Relateddocuments 5
3.2 Locationofappliance 5
3.3 Gas supply 5
3.4 Flue system 5
3.5 Air supply 5
3.6 Watercirculation 5
3.6.1 Pipework 6
3.6.2 Automaticby-pass 6
3.6.3 Drain cocks 6
3.6.4 Airreleasepoints 6
3.6.5 Expansionvessel 6
3.6.6 Fillingpoint 6
3.6.7 Low pressure sealed system 6
3.6.8 Frequentfilling 6
3.7 Electricalsupply 6
3.8 Showers 6
3.9 Mounting ona combustiblesurface 7
3.10 Timberframedbuilding 7
3.11 Inhibitors 7
Generalrequirements(EIRE) Page
3.A1 Relateddocuments 8
3.A2 Locationofappliance 8
3.A3 Gas supply 8
3.A4 Fluesystem 8
3.A5 Airsupply 8
3.A6 Watercirculation 8
3.A6.1 Pipework 8
3.A6.2 Automaticby-pass 8
3.A6.3 Drain cocks 8
3.A6.4 Airreleasepoints 8
3.A6.5 Expansionvessel 8
3.A6.6 Fillingpoint 9
3.A6.7 Low pressure sealed system 9
3.A6.8 Frequentfilling 9
3.A7 Electricalsupply 9
3.A8 Showers 9
3.A9 Mountingonacombustiblesurface 9
3.A10 Timberframedbuilding 9
3.A11 Inhibitors 9
3.A12 Declarationofconformity 9
Installation Page
4.1 Delivery 10
4.2 Contents 10
4.3 Unpacking 10
4.4 Preparationformountingtheappliance 10
4.5 Fittingtheflue 10
4.5.1 Concentrichorizontalflue 10
4.5.2 Concentricverticalflue 11
4.5.3 Twin flue system 12
4.6 Connecting thegasand water 14
4.6.1 Gas 14
4.6.2 Flow andreturn 14
4.6.3 Coldwaterinlet 14
4.6.4 Hotwateroutlet 14
4.6.5 Safetyvalve 14
4.6.6 Condensepipe 14
4.7 Electricalconnections 14
4.7.1 Casingremoval 15
4.7.2 Applianceterminal block 15
4.7.3 Connectingthemains(230V)input 15
Commissioning Page
5.1 Gassupplyinstallation 16
5.2 The heatingsystem 16
5.3 Initial fillingof thesystem 16
5.4 Initialflushing 16
5.5 Filling the hotwater system 16
5.6 Pre-operationchecks 16
5.7 Initiallighting 16
5.7.1 Checkingburnerpressures 16
5.8 Final flushingof theheatingsystem 16
5.8.1 Inhibtors 16
5.9 Settingtheboileroperatingtemperature 16
5.9.1 SettingtheDHWtemperature 17
5.10 Settingthe systemdesign pressure 17
5.11 Regulatingthehotwater 17
5.11.1 Changingtheflowrestrictor 17
5.11.2 Regulatingthecentralheatingsystem 17
5.12 Finalchecks 17
5.13 Instructingtheuser 17
Servicinginstructions Page
6.1 General 18
6.2 Routineannualservicing 18
6.3 Replacementofcomponents 18
6.4 Componentremovalprocedure 18
6.5 Pumpassembly 18
6.6 Safety valve 18
6.7 Automatic airreleasevalve 19
6.8 Water pressure switch 19
6.9 Pressuregauge 19
6.10 Primarythermistor 19
6.11 Highlimitthermostat 19
6.12 PCB 19
6.13 Gas valve 19
6.14 Integraltimeswitch 20
6.15 Electrode,burnerthermostat,burner& injectors 20
6.16 Fluefan 21
6.17 Mainheatexchanger 21
6.18 Air pressure switch 21
6.19 Flowrestrictor 21
6.20 DHW flow switch 22
6.21 DHWheatexchanger 22
6.22 Valveactuator 22
6.23 Divertorvalvecartridge 22
6.24 DHWthermistor 22
6.25 Automaticby-pass 22
6.26 DHWnon-returnvalve 22
6.27 Expansionvessel 22
6.27.1 Expansion vessel removal (with sufficient clearance above) 22
6.27.2 Expansion vessel removal (withinsufficient clearanceabove) 23
6.28.1 Latentheatcollector 23
6.28.2 Dismantlingthelatentheatcollector 23
6.28.3 Retarder 23
6.29 Condensetrapremoval 24
Checks,adjustmentsandfault finding page
7.1 Checkingapplianceoperation 24
7.2 Appliancemodeofoperation 24
7.2.1 Selector switch in the OFF position 24
7.2.2 Selector switch in the hot water only position 24
7.2.3 Selector switch in the heating & hot water position 24
7.2.4 Appliancefunctions 24
7.2.5 DHWmode 24
7.2.6 Heatingmode 25
7.3 Checking &adjustingburnerpressure 26
7.3.1 Settingthe maximum burnerpressure 26
7.3.2 Settingthe minimum burnerpressure 26
7.3.3 Settingthe minimum CHoutput 26
7.4 Combustionanalysistest 26
7.5 Checking theexpansionvessel 27
7.6 Externalfaults 27
7.6.1 Installationfaults 27
7.7 Electrical checks 27
7.7.1 Earthcontinuitytest 27
7.7.2 Short circuit check 27
7.7.3 Polaritycheck 27
7.7.4 Reversedpolarity orsupply fault 28
7.7.5 Resistance to earth check 28
7.8 Faultfinding 28
7.8.1 ReplacingthemainPCB 28
7.9 Faultcodes 28
7.10 Faultfinding 29-34
Wiringdiagrams Page
8.1 Externalwiring 35
8.2 Typicalcontrolapplications 35
8.3 Vokeraremotecontrol 35
8.4 Roomthermostat 35
8.5 Othercontrols 35
Functionaldiagram 36
Explodeddiagrams Page
Table1-5 37-41
L.P.G.instructions Page
10.1 Relateddocuments 42
10.2 Technicaldata 42
10.3 Convertingtheappliancegassupply 42
10.4 Gas supply 42
10.5 Gassupplyinstallation 42
10.6 Checking&adjusting burnerpressure 42
10.6.1 Settingthemaximumburnerpressure 42
10.6.2 Settingtheminimumburnerpressure 42

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INTRODUCTION
Fig.1 General Layout
1 Diverter valve motor
2 Discharge valve
3 Domestic hot water heat exchanger
4 Safety valve
5 Pump
6 Pressure switch
7 Auto air vent (AAV)
8 Electrode
9 Main burner
10 Main heat exchanger
11 Latent heat collector
12 Flue gas analysis test point
13 Flue outlet
14 Air intake
15 Differential pressure switch
16 Silicone pressure tube (-)
17 Silicone pressure tube (+)
18 Fan assembly
19 CH NTC sensor
20 Combustion chamber
21 High limit thermostat
22 Expansion vessel
23 Condensate pressure switch
24 Ignition transformer
25 Condense trap
26 Modulator coil
27 Gas valve
28 DHW flow switch
29 Pressure gauge
30 DHW temperature selector
31 Mode selector switch
32 Status fault/indicator led
33 CH temperature selector
34 Timeclock
The Compact HE range of appliances is comprised of 2
models of high-efficiency combination boiler with inputs
to heating & DHW of 25, 29 & 35kW respectively. Each
appliance - by design - incorporates electronic ignition,
circulating pump, expansion vessel, safety valve, pres-
sure gauge, and automatic by-pass.
The Compact HE range is produced as room sealed,
category II2H3P appliances, suitable for internal wall
mountingapplications only.Theyare providedwith afan
powered flue outlet with an annular coaxial combustion
air intake that can be rotated - horizontally - through 360
degrees for various horizontal or vertical applications.
TheCompactHErangecanalsobeusedwiththeVokera
twin flue system.
The Compact HE range is approved for use with C12 &
C32 type flue applications.
These appliances are designed for use with a sealed
system only; consequently they are not intended for use
on open vented systems
Fig. 1
29 30 31 32 33 34

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SECTION 1 DESIGN PRINCIPLES AND OPERATING SEQUENCE
Fig. 2
1.1 PRINCIPLE COMPONENTS
●A fully integrated electronic control board fea-
turing electronic temperature control, anti-cy-
clecontrol,pump over-run,LEDfaultindicator,
full gas modulation.
●Low-water-content, copper heat exchanger.
●Electronic ignition with flame supervision.
●Integral high-head pump.
●Fan.
●Air pressure switch.
●Expansion vessel.
●Water pressure switch.
●Two-stage gas valve.
●Pressure gauge.
●Safety valve.
●Condense switch.
1.2 MODE OF OPERATION (at rest)
When the appliance is at rest and there are no
requests for heating or DHW, the following func-
tions are active:
●Frost-protection system - the frost-protection
system protects the appliance against the risk
offrostdamage.Shouldthetemperatureofthe
appliance fall to 5 °C, the boiler will function in
the heating mode at minimum power until it
reaches 35 °C.
●Anti-block function - the anti-block function
enables the pump and divertor valve actuator,
to be energised for short periods, when the
appliance has been inactive for more than 19-
hours.
1.3 MODE OF OPERATION (Heating)
Whenthereisarequestforheatviathetimeclock
and/oranyexternalcontrol,thepumpandfanare
started, the fan will then prove the air pressure
switch. At this point an ignition sequence is
enabled.
Ignition is sensed by the electronic circuitry to
ensure flame stability at the burner. Once suc-
cessfulignitionhasbeenachieved,theelectronic
circuitry increases the gas rate to 75% for a
period of 15 minutes. Thereafter, the boiler’s
output will either be increase to maximum or
modulate to suit the set requirement.
When the appliance reaches the desired tem-
perature the burner will shut down and the boiler
will perform a three-minute anti-cycle (timer de-
lay).
Whenthe requestfor heathasbeensatisfiedthe
appliancepumpandfanmaycontinuetooperate
to dissipate any residual heat within the appli-
ance.
1.4 MODE OF OPERATION (DHW)
When there is a request for DHW via a hot water
outletortap,thepumpandfanarestarted,thefan
will then prove the air pressure switch. At this
point an ignition sequence is enabled.
Ignition is sensed by the electronic circuitry to
ensure flame stability at the burner. Once suc-
cessfulignitionhasbeenachieved,theelectronic
circuitry increases the gas rate to maximum or
willmodulateoutput tostabilisethe temperature.
In the event of the appliance exceeding the
desired temperature the burner will shut down
until the temperature drops.
WhentherequestforDHWhasbeensatisfiedthe
appliancepumpandfanmaycontinuetooperate
to dissipate any residual heat within the appli-
ance.
1.5 SAFETY DEVICES
When the appliance is in use, safe operation is
ensured by:
●A water pressure switch that monitors system
water pressure and will de-activate the pump,
fan and burner should the system water pres-
sure drop below the rated tolerance.
●A high limit thermostat that over-rides the tem-
perature control circuit to prevent or interrupt
the operation of the burner.
●An air pressure switch that requires the fan to
prove operation before the gas valve is ener-
gised.
●A pressure switch that interrupts the operation
ofthe appliance ifthe condensepipe becomes
blocked.
●Asafetyvalvewhichreleasesexcesspressure
from the primary circuit.
CH
return CH flow DHW outlet Domestic cold water inlet
safety valve
automatic
by-pass
diverter
valve motor
pump
AAV
expansion
vessel
latent heat
collector
flue
outlet air intake
pressure
switch
main heat
exchanger
CH NTC
sensor
main
burner
gas valve
DHW heat
exchanger DHW tempera-
ture sensor
water
pressure
switch
DHW non
return valve
DHW
flow switch

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SECTION 2 TECHNICAL DATA
Ref.Condition 15 °C , 1013,25 mbar, dry gas
NOTE: L.P.G.data refer to section 10
25 29
2.1Central heating
Heat input (kW) 25.0 29.0 34.8
Maximum heat output@ 80/60 °C (kW) 24.3 28.1 33.8
Minimum heat output@ 80/60 °C (kW) 14.2 14.2 13.9
Maximum heat output@ 50/30 °C (kW) 25.9 30.2 36.1
Minimum heat output@ 50/30 °C (kW) 14.9 14.8 14.4
Minimumworkingpressure 0.5bar 0.5bar 0.5bar
Maximumworkingpressure 3.0bar 3.0bar 3.0bar
Minimumflow rate 350l/h 350l/h 350 l/h
2.2 Domestic hot water
Maximumoutput(kW) 25.0 29.0 34.8
Minimumoutput (kW) 9.5 9.9 9.9
Flow rate (35 °C rise) 10.2l/min 11.9l/min 14.3l/min
Maximuminletpressure 6.0bar 6.0bar 6.0bar
Minimuminletworkingpressure 0.15bar 0.15bar 0.15bar
Minimumflowrate 2 l/min. 2 l/min. 2 l/min.
2.3Gaspressures
Inlet pressure G20 20.0mbar 20.0mbar 20.0mbar
Maximumburnerpressure 9.40mbar 9.20mbar 10.1mbar
Minimumburnerpressure (centralheating) 3.50mbar 2.70mbar 2.10mbar
Minimumburnerpressure (domestichotwater) 1.50mbar 1.20mbar 1.00mbar
Gross rate (central haeting, max - min) 2.64 - 1.59 m3/h 3.07 - 1.59 m3/h 3.68 - 1.59 m3/h
Injectors size 12 x 1.35 mm 14 x 1.35 mm 16 x 1.35 mm
2.4Expansionvessel
Capacity 8 litres 10 litres 10 litres
Maximumsystem volume 76 litres 76 litres 76 litres
Pre-chargepressure 1.0bar 1.0 bar 1.0bar
2.5Dimensions
Height 780mm 780mm 780mm
Width 400mm 450mm 500mm
Depth 332mm 332mm 332mm
Dry weight 40 kg 44 kg 48 kg
2.6Clearances
Sides 12 mm 12 mm 12 mm
Top 150 mm from casing or 25 mm above flue elbow, whichever is applicable
Bottom 150mm 150mm 150mm
Front 600mm 600mm 600mm
2.7Connections
Flow & return 22 mm 22 mm 22 mm
Hot & cold water connections 15 mm 15 mm 15mm
Gas 15mm 15 mm 15mm
Safetyvalve 15mm 15 mm 15mm
Condense 21 mm 21 mm 21 mm
2.8Electrical
Voltage 230V/~50Hz 230V/~50Hz 230V/~50Hz
Powerconsumption 153W 153W 153 W
Internalfuse 2 A 2 A 2 A
Externalfuse 3 A 3 A 3 A
2.9Flue details(concentric)
Maximumhorizontalfluelength(60/100mm) 4.5 m 4.0 m 1.85 m
Maximumvertical fluelength(60/100mm) 5.5 m 5.0 m 2.85m
Maximumhorizontalfluelength(80/125mm) 11.0 m 9.0 m 6.8 m
Maximumvertical fluelength(80/125mm) 12.0 m 10.0 m 7.8 m
2.9 Flue details (twin pipe)
Maximumhorizontalflue length(80mm+80mm) 20 m + 20 m 12 m + 12 m 10 m + 10 m
Maximum verticalfluelength(80mm+80mm) 20 m + 20 m 12 m + 12 m 10 m + 10 m
2.10Efficiency
SEDBUK 86.9Band“B” 87.1Band“B” 86.65 Band“B”
35

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2.11 PUMP DUTY
Fig. 3 shows the flow rate available - after allowing for pressure loss through the appliance - for system
requirements. When using this graph, apply only the pressure loss of the system. The graph is based on a
20 ºC temperature differential.
Fig. 4
SECTION 3 GENERAL REQUIREMENTS (UK)
2.12Appliance
NOx 98 ppm - 172 mg/kWh 81 ppm - 142 mg/kWh 85 ppm - 149 mg/kWh
CO (max-min) 80 ppm - 80 ppm 100 ppm - 60 ppm 100 ppm - 120 ppm
CO2(max-min) 6.75 - 3.90 % 7.05 - 3.40 % 6.8 - 2.7 %
CO/CO2ratio (max) 0.001 to 1 0.001 to 1 0.001 to 1
CO/CO2ratio (min) 0.002 to 1 0.001 to 1 0.004 to 1
25 29 35
Fig. 3 Litres Per Hour (x100)
Residual head (x 100 mbar)
Key Location Minimum distance
A Below an opening (window, air-brick, etc.) 300 mm
B Above an opening (window, air-brick, etc.) 300 mm
C To the side of an opening (window, air-brick, etc.) 300 mm
D Below gutter, drain-pipe, etc. 75 mm
E Below eaves 200 mm
F Below balcony, car-port roof, etc. 1200 mm
G To the side of a soil/drain-pipe, etc. 150 mm
H From internal/external corner or boundary 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 a terminal 1200 mm
L From an opening in the car-port into the building 1200 mm
M Vertically from a terminal on the same wall 1500 mm
N Horizontally from a terminal on the same wall 300 mm
P From a structure to the side of the vertical terminal 500 mm
Q From the top of the vertical terminal to the roof flashing As determined by the fixed collar
of the vertical terminal
25 - 29
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300
firstspeed
secondspeed
thirdspeed
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
5,5
6,0
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
35
Litres Per Hour (x100)
Residual head (x 100 mbar)
firstspeed
secondspeed
thirdspeed

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This appliance must be installed by a competent
personinaccordancewiththeGasSafety(Instal-
lation & Use) Regulations.
3.1 RELATED DOCUMENTS
The installation of this boiler must be in accord-
ance with the relevant requirements of the Gas
Safety(Installation & Use)Regulations, thelocal
building regulations, the current I.E.E. wiring
regulations, the bylaws of the local water under-
taking, the Building Standards (Scotland) Regu-
lation and Building Standards (Northern Ireland)
Regulations.
Itshould bein accordancealso withany relevant
requirements of the local authority and the rel-
evant recommendations of the following British
Standard Codes of Practice.
3.2 LOCATION OF APPLIANCE
The appliance may be installed in any room or
internal space, although particular attention is
drawn to the requirements of the current I.E.E.
wiringregulations, and inScotland, theelectrical
provisions of the Building Regulations, with re-
specttotheinstallationoftheapplianceinaroom
or internal space containing a bath or shower.
When an appliance is installed in a room or
internal space containing a bath or shower, the
appliance or any control pertaining to it must not
be within reach of a person using the bath or
shower.
The location chosen for the appliance must per-
mit the provision of a safe and satisfactory flue
andtermination.Thelocationmustalsopermitan
adequate air supply for combustion purposes
and an adequate space for servicing and air
circulation around the appliance. Where the in-
stallation of the appliance will be in an unusual
location special procedures may be necessary,
BS 6798 gives detailed guidance on this aspect.
A compartment used to enclose the appliance
must be designed and constructed specifically
for this purpose. An existing compartment/cup-
board may be utilised provided that it is modified
to suit.
Details of essential features of compartment/
cupboarddesignincludingairingcupboardinstal-
lationsaregiveninBS6798.Thisapplianceisnot
suitable for external installation.
3.3 GAS SUPPLY
The gas meter – as supplied by the gas supplier
–mustbecheckedtoensurethatitisofadequate
size to deal with the maximum rated input of all
the appliances that it serves. Installation pipes
must be fitted in accordance with BS 6891.
Pipe work from the meter to the appliance must
be of adequate size. Pipes of a smaller size than
the appliance gas inlet connection must not be
used. The installation must be tested for sound-
ness in accordance with BS6891.
Ifthegassupplyservesmorethanoneappliance,
it must be ensured that an adequate supply is
maintained to each appliance when they are in
use at the same time.
3.4 FLUE SYSTEM
Theterminalshouldbelocatedwherethedisper-
sal of combustion products is not impeded and
withdueregardforthedamageanddiscoloration
thatmayoccurtobuildingproductslocatednearby.
Theterminalmustnotbelocatedinaplacewhere
it is likely to cause a nuisance (see fig. 4).
Watervapourwillcondenseonleavingthetermi-
nal and the effect of such pluming must be
considered.
BS 5440 PART 1 FLUES
BS 5440 PART 2 FLUES & VENTILATION
BS 5449 PART 1 FORCED CIRCULATION HOT WATER SYSTEMS
BS 5546 INSTALLATION OF GAS HOT WATER SUPPLIES FOR DOMESTIC PURPOSES
(2ND FAMILY GASES)
BS 6798 INSTALLATION OF BOILERS OF RATED INPUT NOT EXCEEDING 60kW
BS 6891 LOW PRESSURE INSTALLATION PIPES
BS 7074 PART 1 APPLICATION, SELECTION AND INSTALLATION OF EXPANSION VESSELS AND
ANCILLARY EQUIPMENT FOR SEALED WATER SYSTEMS
If installed less than 2m above a pavement or
platform to which people have access (including
balconies or flat roofs) the terminal must be
protected by a guard of durable material. The
guard must be fitted centrally over the terminal.
Refer to BS 5440 Part 1, when a terminal is sited
less than 1m below a plastic gutter, or less than
500mm below a painted surface, a suitable one
metre long heat shield should be fitted.
3.5 AIR SUPPLY
The following notes are intended for general
guidance only.
Thisapplianceisaroom-sealed,fan-fluedboiler,
consequentlyit does notrequire apermanent air
vent for combustion air supply.
When installed in a cupboard or compartment,
ventilation for cooling purposes is also not re-
quired.
3.6 WATER CIRCULATION
Detailedrecommendations aregivenin BS5449
Part 1 and BS 6798. The following notes are for
general guidance only.

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Fig. 5a
3.6.7 LOW PRESSURE SEALED SYSTEM
An alternative method of filling the system would
be from an independent make-up vessel or tank
mounted in a position at least 1 metre above the
highest point in the system and at least 5 metres
above the boiler (see fig. 5a).
The cold feed from the make-up vessel or tank
must be fitted with an approved non-return valve
and stopcock for isolation purposes. The feed
pipe should be connected to the return pipe as
close to the boiler as possible.
3.6.8 FREQUENT FILLING
Frequent filling or venting of the system may be
indicative of a leak. Care should be taken during
the installation of the appliance to ensure all
aspects of the system are capable of withstand-
ing pressures up to at least 3 bar.
3.7 ELECTRICAL SUPPLY
The appliance is supplied for operation on 230V
@ 50Hz electrical supply; it must be protected
with a 3-amp fuse. The method of connection to
the mains electricity supply must allow for com-
plete isolation from the supply. The preferred
method is by using a double-pole switch with a
contact separation of at least 3mm. The switch
must only supply the appliance and its corre-
sponding controls, i.e. time clock, room thermo-
stat, etc. Alternatively an un-switched shuttered
socket with a fused 3-pin plug both complying
with BS 1363 is acceptable.
3.8 SHOWERS
Iftheapplianceisintendedforusewithashower,
the shower must be thermostatically controlled
andbesuitableforuse withacombinationboiler.
3.6.1 PIPEWORK
ItisrecommendedthatcoppertubingtoBS2871
Part 1 is used in conjunction with soldered capil-
lary joints.
Where possible pipes should have a gradient to
ensureairiscarriednaturallytoairreleasepoints
and that water flows naturally to drain cocks.
Exceptwhereprovidingusefulheat,pipesshould
beinsulatedtoavoidheatlossandinparticularto
avoid the possibility of freezing. Particular atten-
tion should be paid to pipes passing through
ventilatedareas such asunder floors,loft space,
and void areas.
3.6.2 AUTOMATIC BY-PASS
The appliance has a built-in automatic by-pass.
However it may be necessary to fit an external
bypass should the design of the heating system
require such. In any case, the design of the
system should be such that it prevents boiler
‘cycling’.
3.6.3 DRAIN COCKS
Thesemust be locatedin accessible positionsto
facilitate draining of the appliance and all water
pipes connected to the appliance. The drain
cocks must be manufactured in accordance with
BS 2879.
3.6.4 AIR RELEASE POINTS
Thesemustbepositionedatthehighestpointsin
thesystem whereairis likelytobe trapped.They
should be used to expel trapped air and allow
complete filling of the system.
3.6.5 EXPANSION VESSEL
The appliance has an integral expansion vessel
to accommodate the increased volume of water
when the system is heated. It can accept up to 8
litres (25kW) or 10 litres (29 & 35kW) of expan-
sion from within the system, generally this is
sufficient, however if the system has an unusu-
ally high water content, it may be necessary to
provideadditionalexpansioncapacity(see6.19).
3.6.6 FILLING POINT
Anapprovedmethodforinitialfillingofthesystem
and replacing water lost during servicing etc. is
required (see fig. 5). This method of filling must
comply with the current Water Supply (Water
Fittings) Regulations 1999 and Water Bylaws
2000 (Scotland).
Fig. 5
control valve
temporary
connection control valve
supply pipe
double check
valve
flow/return
pipe
Make-up vessel
or tank
Automatic
air-vent
Non-return
valve Stopcock
5.0 metres minimum
Heating
return

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3.9 MOUNTING ON A COMBUSTIBLE SURFACE
If the appliance is to be fitted on a wall of
combustible material, a sheet of fireproof mate-
rial must protect the wall.
3.10 TIMBER FRAMED BUILDING
If the appliance is to be fitted in a timber framed
building,itshouldbefittedinaccordancewiththe
Institute of Gas Engineers publication (IGE/UP/
7) ‘Guide for Gas Installations in Timber Frame
Buildings’.
3.11 INHIBITORS
Vokerarecommendthataninhibitor-suitablefor
usewith copperandaluminium heatexchangers
-isusedtoprotecttheboilerandsystemfromthe
effects of corrosion and/or electrolytic action.
The inhibitor must be administered in strict ac-
cordance with the manufacturers instructions*.
*Watertreatmentofthecompleteheatingsystem
- including the boiler - should be carried out in
accordance with BS 7593 and the Domestic
Water Treatment Association’s (DWTA) code of
practice. Fig. 6a
Fig. 6
25kW
35kW
30kW

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SECTION 3A GENERAL REQUIREMENTS (EIRE)
This appliance must be installed by a competent
person in accordance with and defined by, the
Standard Specification (Domestic Gas Installa-
tions) Declaration (I.S. 813).
3A.1 RELATED DOCUMENTS
The installation of this boiler must be in accord-
ance with the relevant requirements of the local
building regulations, the current ETCI National
Rules for Electrical Installations, and the bylaws
of the local water undertaking.
Itshould bein accordancealso withany relevant
requirementsofthelocaland/ordistrictauthority.
3A.2 LOCATION OF APPLIANCE
The appliance may be installed in any room or
internal space, although particular attention is
drawn to the requirements of the current ETCI
National Rules for Electrical Installations, and
I.S. 813, Annex K.
When an appliance is installed in a room or
internal space containing a bath or shower, the
appliance or any control pertaining to it must not
be within reach of a person using the bath or
shower.
The location chosen for the appliance must per-
mit the provision of a safe and satisfactory flue
andtermination.Thelocationmustalsopermitan
adequate air supply for combustion purposes
and an adequate space for servicing and air
circulation around the appliance. Where the in-
stallation of the appliance will be in an unusual
location special procedures may be necessary,
refer to I.S. 813 for detailed guidance on this
aspect. A compartment used to enclose the
appliance must be designed and constructed
specificallyforthispurpose.Anexistingcompart-
ment/cupboardmay be utilisedprovided thatit is
modified to suit.
This appliance is not suitable for external instal-
lation.
3A.3 GAS SUPPLY
The gas meter - as supplied by the gas supplier
-mustbecheckedtoensurethatitisofadequate
size to deal with the maximum rated input of all
the appliances that it serves. Installation pipes
must be fitted in accordance with I.S. 813.
Pipe work from the meter to the appliance must
be of adequate size.Pipes of a smaller size than
the appliance gas inlet connection must not be
used.The installation must be tested for sound-
ness in accordance with I.S.813.
Ifthegassupplyservesmorethanoneappliance,
it must be ensured that an adequate supply is
maintained to each appliance when they are in
use at the same time.
3A.4 FLUE SYSTEM
Theterminalshouldbelocatedwherethedisper-
sal of combustion products is not impeded and
withdueregardforthedamageanddiscoloration
thatmayoccurtobuildingproductslocatednearby.
Theterminalmustnotbelocatedinaplacewhere
itislikelytocauseanuisance(refertoI.S.813for
guidance on permitted locations and minimum
distances of flue terminals).
Watervapourwillcondenseonleavingthetermi-
nal; the effect of such pluming must be consid-
ered.
If installed less than 2m above a pavement or
platform to which people have access (including
balconies or flat roofs) the terminal must be
protected by a guard of durable material. The
guard must be fitted centrally over the terminal.
RefertoI.S.813,whentheterminalis0.5metres
(or less) below plastic guttering or 1 metre (or
less) below painted eaves.
3A.5 AIR SUPPLY
The following notes are intended for general
guidance only. This appliance is a room-sealed,
fan-flued boiler, consequently it does not require
a permanent air vent for combustion air supply.
When installed in a cupboard or compartment,
ventilation for cooling purposes is also not re-
quired.
3A.6 WATER CIRCULATION
Specific recommendations are given in I.S. 813.
Thefollowing notesare forgeneral guidanceonly.
3A.6.1 PIPEWORK
It is recommended that copper tubing be used in
conjunction with soldered capillary joints.
Where possible pipes should have a gradient to
ensureairiscarriednaturallytoairreleasepoints
and that water flows naturally to drain cocks.
Exceptwhereprovidingusefulheat,pipesshould
beinsulatedtoavoidheatlossandinparticularto
avoid the possibility of freezing. Particular atten-
tion should be paid to pipes passing through
ventilatedareas such asunder floors,loft space,
and void areas.
3A.6.2 AUTOMATIC BY-PASS
The appliance has a built-in automatic by-pass.
However it may be necessary to fit an external
bypass should the design of the heating system
require such. In any case, the design of the
system should be such that it prevents boiler
‘cycling’.
3A.6.3 DRAIN COCKS
Thesemust be locatedin accessible positionsto
facilitate draining of the appliance and all water
pipes connected to the appliance.
3A.6.4 AIR RELEASE POINTS
Thesemustbepositionedatthehighestpointsin
thesystem whereairis likelytobe trapped.They
should be used to expel trapped air and allow
complete filling of the system.
3A.6.5 EXPANSION VESSEL
The appliance has an integral expansion vessel
to accommodate the increased volume of water

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9
when the system is heated. It can accept up to 8
litres (25kW) or 10 litres (29 & 35kW) of expan-
sion from within the system, generally this is
sufficient, however if the system has an unusu-
ally high water content, it may be necessary to
provideadditionalexpansioncapacity(see6.19).
3A.6.6 FILLING POINT
A suitable method for initial filling of the system
and replacing water lost during servicing etc. is
required (see fig. 5). You should ensure this
method of filling complies with the local water
authority regulations.
3A.6.7 LOW PRESSURE SEALED SYSTEM
An alternative method of filling the system would
be from an independent make-up vessel or tank
mounted in a position at least 1 metre above the
highest point in the system and at least 5 metres
above the boiler (see fig. 5A).
The cold feed from the make-up vessel or tank
must be fitted with an approved non-return valve
and stopcock for isolation purposes. The feed
pipe should be connected to the return pipe as
close to the boiler as possible.
3A.6.8 FREQUENT FILLING
Frequent filling or venting of the system may be
indicative of a leak. Care should be taken during
the installation of the appliance to ensure all
aspects of the system are capable of withstand-
ing pressures up to at least 3 bar.
3A.7 ELECTRICAL SUPPLY
The appliance is supplied for operation on 230V
@ 50Hz electrical supply; it must be protected
with a 3-amp fuse. The method of connection to
the mains electricity supply must allow for com-
plete isolation from the supply. The preferred
method is by using a double-pole switch with a
contact separation of at least 3mm. The switch
must only supply the appliance and its corre-
sponding controls, i.e. time clock, room thermo-
stat, etc.
3A.8 SHOWERS
Iftheapplianceisintendedforusewithashower,
the shower must be thermostatically controlled
andbesuitableforuse withacombinationboiler.
3A.9 MOUNTING ON A COMBUSTIBLE SURFACE
If the appliance is to be fitted on a wall of
combustible material, a sheet of fireproof mate-
rial must protect the wall.
3A.10 TIMBER FRAMED BUILDINGS
If the appliance is to be fitted in a timber framed
building,itshouldbefittedinaccordancewithI.S.
813 and local Building Regulations.
The Institute of Gas Engineers publication (IGE/
UP/7) ‘Guide for Gas Installations in Timber
Frame Buildings’ gives specific advice on this
type of installation.
3A.11 INHIBITORS
Vokerarecommendthataninhibitor-suitablefor
usewith copperandaluminium heatexchangers
-isusedtoprotecttheboilerandsystemfromthe
effects of corrosion and/or electrolytic action.
The inhibitor must be administered in strict ac-
cordance with the manufacturers’ instructions*.
*Watertreatmentofthecompleteheatingsystem
- including the boiler - should be carried out in
accordance with I.S. 813 and the Domestic Wa-
ter Treatment Association’s (DWTA) code of
practice.
3A.12 DECLARATION OF CONFORMITY
A Declaration of Conformity (as defined in I.S.
813) must be provided on completion of the in-
stallation.
A copy of the declaration must be given to the
responsiblepersonandalsotothegassupplierif
required.

Supplied By www.heating spares.co Tel. [phone]
10
SECTION 4 INSTALLATION
4.1 DELIVERY
Due to the weight of the appliance it may be
necessary for two people to lift and attach the
appliance to its mounting. The appliance is con-
tainedwithinaheavy-dutycardboardcarton.Lay
thecarton onthe floorwith thewriting thecorrect
way up.
4.2 CONTENTS
Contained within the carton is:
●the boiler
●the wall bracket
●appliance template
●anaccessoriespackcontainingapplianceserv-
ice connections and washers
●the instruction pack containing the installation
& servicing instructions, user instructions,
Benchmarklogbook,guaranteeregistrationcard
and a 3-amp fuse.
4.3 UNPACKING
At the top of the carton pull both sides open - do
notusea knife-unfold therestofthe cartonfrom
around the appliance, carefully remove all pro-
tectivepackagingfromtheappliance,andlaythe
accessories etc. to one side. Protective gloves
shouldbeusedtolifttheappliance,theappliance
back-frame should be used for lifting points.
4.4 PREPARATION FOR MOUNTING THE APPLI-
ANCE
The appliance should be mounted on a smooth,
vertical,non-combustiblesurface,whichmustbe
capable of supporting the full weight of the appli-
ance. Care should be exercised when determin-
ing the position of the appliance with respect to
hidden obstructions such as pipes, cables, etc.
When the position of the appliance has been
decided - using the template supplied - carefully
mark the position of the wall- mounting bracket
(see fig. 6) and flue-hole (if applicable).
4.5 FITTING THE FLUE
The top flue outlet permits both horizontal and
vertical flue applications to be considered, alter-
natively, the Vokera twin flue system can be
utilised if longer flue runs are required.
4.5.1 CONCENTRIC HORIZONTAL FLUE
(For concentric vertical flue, see section 4.5.2).
(For twin flue applications, see section 4.5.3).
TheappliancecanbeusedwitheithertheVokera
condensing60/100mmconcentricfluesystemor
the optional 80/125mm concentric flue system.
NOTE
These instructions relate only to the Vokera con-
densing 60/100mm concentric flue system. For
specificdetailsontheinstallationofthe80/125mm
concentric flue system please refer to the instruc-
tions supplied with the 80/125mm terminal.
The appliance flue outlet elbow can be rotated
through 360º on its vertical axis. In addition the
fluemaybeextendedfromtheoutletelbowinthe
horizontalplane (see 2.9).A reductionmust also
be made to the maximum length (see table
below) when additional bends are used.
Bend Reduction in maximum flue length for each bend
45ºbend 0.5 metre
90ºbend 1.0 metre
Reduction for additional bends
Using the template provided, mark and drill a
115mmholeforthepassageofthefluepipe.The
hole should be drilled level to ensure any con-
densefluidthatformswilldrainbacktotheboiler.
The fixing holes for the wall-mounting bracket
should now be drilled and plugged, an appropri-
ate type and quantity of fixing should be used to
ensure that the bracket is mounted securely.
Once the bracket has been secured to the wall,
mount the appliance onto the bracket.
FITTING THE HORIZONTAL FLUE KIT
Carefullymeasurethedistancefromthecentreof
the appliance flue outlet to the edge of the fin-
ished outside wall (dimension X). Add 45mm to
dimensionXtogiveyouDimensionY(seefig7A).
Measure dimension Y from the terminal end of
the concentric flue pipe and cut off the excess
ensuring any burrs are removed. Pass the con-
centric flue pipe through the previously drilled
hole.Fit thefluebend tothe boilerflue outletand
insert the concentric flue pipe into the flue bend
ensuring the correct seal is made.
Using the clamp, gasket, and screws supplied,
securetheflue bendto the applianceflue spigot.
The 60mm M & F adaptor (supplied with the flue
kit) should be discarded.
NOTE
Fit the internal (White) trim to the flue assembly
prior to connecting the flue pipe to the bend.
You must ensure that the entire flue system is
properly supported and connected.
Seal the flue assembly to the wall using cement
ora suitablealternative thatwillprovide satisfac-
tory weatherproofing. The exterior trim (Black)
can now be fitted.
Fig. 7
Part No. Description Min-Max Length
0225720 Horizontal flue kit for use with 1000mm
add.bends &extensions
0225755 Telescopicextension 350 mm – 500 mm
0225740 0.5mextension 500mm
0225745 1.0mextension 1000mm
0225750 2.0mextension 2000mm
0225730 45ºbend(pair) N/A
0225735 90ºbend N/A
0225760 Wall bracket (5) N/A
Horizontal flue terminals and accessories
Boiler
Push-fitconnection
outer
clamp
Terminalor
extension

Supplied By www.heating spares.co Tel. [phone]
11
4.5.1.1 EXTENDING THE FLUE
Connect the bend - supplied with the terminal kit
- to the top of the boiler using clamp (supplied)
seefig.7.Theadditionalbends& extensions have
push-fit connections, care should be taken to
ensure that the correct seal is made when as-
sembling the flue system. Connect the required
number of flue extensions or bends (up to the
maximum equivalent flue length) to the flue ter-
minal (see fig. 7 & 8).
The flue pipe should have a minimum 1-degree
rise from the boiler (17mm every 1.0 metre) to
ensurethatanycondensefluiddrainsbacktothe
appliance.
NOTE
Whencutting anextensiontotherequired length,
you must ensure that the excess is cut from the
plain end of the extension (see fig. 7 & 8). Re-
move any burrs, and check that all seals are lo-
cated properly.
You must ensure that the entire flue system is
properly supported and connected.
Seal the flue assembly to the wall using cement
or a suitable alternative that will provide satisfac-
tory weatherproofing.
4.5.2 CONCENTRIC VERTICAL FLUE
TheappliancecanbeusedwitheithertheVokera
condensing60/100mmconcentricfluesystemor
the optional 80/125mm concentric flue system.
NOTE
These instructions relate only to the Vokera con-
densing 60/100mm concentric flue system. For
specificdetailsontheinstallationofthe80/125mm
concentric flue system please refer to the instruc-
tions supplied with the 80/125mm terminal.
The vertical flue terminal can be connected di-
rectly to the appliance flue outlet. Alternatively,
an extension or bend can be connected to the
appliance flue outlet if desired (see 4.4.2), how-
ever if additional bends are fitted, a reduction
must be made to the maximum flue length (see
table below).
Fig. 8
Part No. Description Min-Max Length
0225725 Verticalflueterminal 1.0metre
0225770 Pitchedroofflashingplate N/A
0225765 Flatroofflashingplate N/A
0225755 350-500telescopicextension 350 mm – 500 mm
0225740 0.5mextension 500mm
0225745 1.0mextension 1000mm
0225750 2.0mextension 2000mm
0225730 45ºbend(pair) N/A
0225735 90ºbend N/A
0225760 Wall bracket (4) N/A
Vertical flue terminal and accessories
Using the dimensions given in fig. 9 as a refer-
ence, mark and cut a 107mm hole in the ceiling
and/or roof.
Bend Reduction in maximum flue length for each bend
45ºbend 0.5 metre
90ºbend 1.0 metre
Reduction for bends
Fig. 7a “X” + 45 mm = “Y”
125 mm
FLUE RESTRICTOR RING (horizontal flue)
To ensure maximum efficiency of the appliance,
it may be necessary to fit one of the supplied
flue restrictor rings to the appliance flue outlet
(see tables below).
Total flue length Restrictor required
Lessthan 1.2 metre 82.5mmdiameter
Less than 3.0 metres 88mm diameter
Less than 4.5 metres notrequired
25
Total flue length Restrictor required
Less than 2.0 metres 84mm diameter
Less than 4.0 metres notrequired
29
Total flue length Restrictor required
Lessthan 1.85metres notrequired
35
Fig. 9 145

Supplied By www.heating spares.co Tel. [phone]
12
Fit the appropriate flashing plate to the roof and
insert the vertical flue terminal through the flash-
ingplatefromtheoutside,ensuringthatthecollar
on the flue terminal fits over the flashing.
The fixing holes for the wall-mounting bracket
should now be drilled and plugged, an appropri-
ate type and quantity of fixing should be used to
ensure that the bracket is mounted securely.
Once the bracket has been secured to the wall,
mount the appliance onto the bracket.
IMPORTANT
The vertical flue terminal is 1.0 metre in length
andcannotbecut;thereforeitmaybenecessary
toadjustthe heightoftheappliance tosuitoruse
a suitable extension.
Connecttheverticalflueassemblytotheboilerflue
spigot using the 60mm & 100mm clips, gaskets &
screws (supplied), ensuring the correct seal is
made. The flue support bracket (supplied with the
vertical flue kit) can now be fitted.
If the vertical flue requires extension/s or addi-
tional bend/s, connect the required number of
flue extensions or bends (up to the maximum
equivalent flue length) between the boiler and
vertical flue assembly (see fig. 8).
Ensure that any horizontal sections of the flue
system have a minimum 1º fall back to the boiler
(17mm per 1000mm).
NOTE
Whencutting anextensiontotherequired length,
you must ensure that the excess is cut from the
plain end of the extension (see fig. 8). Remove
any burrs, and check that any seals are located
properly.
You must ensure that the entire flue system is
properly supported and connected.
4.5.3 TWIN FLUE SYSTEM
TheVokeratwinfluesystemenablesgreaterflue
distances to be achieved (see 4.4.2) than that of
a concentric flue system. It can be used for
horizontal or vertical applications, however the
twin flue system must be converted to the dedi-
cated concentric flue kit for termination. It is
essential that the installation of the twin flue
system be carried out in strict accordance with
these instructions.
GUIDANCE NOTES ON TWIN FLUE INSTAL-
LATION
●The flue must have a fall back of 1º back to the
appliancetoallowanycondensatethatmayform
in the flue system to drain via the condensate
drain. Consideration must also be given to the
factthatthereisthepossibilityofasmallamount
of condensate dripping from the terminal.
●Ensurethattheentirefluesystemisadequately
supported, use at least one bracket for each
extension.
●The entire flue system must be adequately
insulated to maintain heat within the flue sys-
temtherebyreducingthepossibilityofconden-
sate production.
●As the exhaust outlet pipe can reach very high
temperatures it must be protected to prevent
persons touching the hot surface.
●The condensate drainpipe must be connected
in accordance with local building regulations
that are in force.
MOUNTING THE BOILER
The fixing holes for the wall-mounting bracket
should now be drilled and plugged, an appropri-
ate type and quantity of fixing should be used to
ensure that the bracket is mounted securely.
Once the bracket has been secured to the wall,
mount the appliance onto the bracket.
Part No. Description Min-Max Length
0225805 Horizontal flueterminal 1.0 metre
0225810 Verticalflue terminal 1.0metre
430 Twin adapterkit N/A
0225770 Pitched roofflashing plate N/A
0225765 Flatroof flashingplate N/A
0225815 Condensatedrain kit N/A
0225820 0.25 m extension (pair) 250 mm
0225825 0.5m extension(pair) 500mm
0225830 1.0m extension(pair) 1000mm
0225835 2.0m extension(pair) 2000mm
0225840 45ºbend (pair) N/A
0225845 90ºbend (pair) N/A
0225850 Twin bracket (5) N/A
0225855 Singlebracket(5) N/A
Twin flue accessories
Bend Reduction in maximum flue length for each bend
45ºbend 1.0 metre
90ºbend 1.0 metre
Reduction for bends
FLUE RESTRICTOR RING (vertical flue)
To ensure maximum efficiency of the appliance,
it may be necessary to fit one of the supplied
flue restrictor rings to the appliance flue outlet
(see tables below).
Total flue length Restrictor required
Lessthan 2.0 metre 82.5mmdiameter
Less than 4.0 metres 88mm diameter
Less than 5.5 metres notrequired
25
Total flue length Restrictor required
Less than 2.8 metres 84mm diameter
Less than 5.0 metres notrequired
29
Total flue length Restrictor required
Less than 2.7 metres notrequired
35
FLUE RESTRICTOR RING (vertical flue)
To ensure maximum efficiency of the appliance,
itmaybenecessary tofit oneof theflue restrictor
rings (supplied with the twin adaptor kit) to the
appliance flue outlet (see tables below).
Total flue length Restrictor required
Lessthan 7.0 metre 40mmdiameter
Lessthan 13.5metres 45mm diameter
Lessthan 19.5metres notrequired
25
Total flue length Restrictor required
Less than 5.0 metres 45mm diameter
Lessthan 12.0metres notrequired
29

Supplied By www.heating spares.co Tel. [phone]
13
4.5.3.2 HORIZONTAL TERMINATION (see fig. 12)
The twin flue system must be converted to the
dedicated concentric flue kit for termination.
●The horizontal terminal is supplied with a built-
in converter box and cannot be shortened.
●A 130mm hole is required for the passage of
the concentric terminal through the wall.
Depending on site conditions it may be prefer-
able to install the terminal assembly prior to fit-
ting the twin flue pipes.
Mark and drill a 130mm hole for the passage of the
horizontal flue terminal, ensuring that there is a mini-
mum 1º fall back to the boiler (17mm per 1000mm).
Insert the terminal assembly into the flue hole.
Push-fit the twin flue pipes onto the concentric
to twin converter box ensuring that the exhaust
pipe connects to the exhaust connection on the
concentric to twin converter.
If necessary cut the plain ends (male) of the twin
fluepipestoallowconnectiontotheconcentricto
twin converter.
AB
C
Fig. 10
Fig. 11
Fig. 12
Fig. 13
4.5.3.1 INSTALLATION OF TWIN ADAPTOR KIT (fig.
10 & 11)
●Insert the exhaust connection manifold (A)
onto the appliance flue outlet.
●Removethe blankingplate(located totheright
of the appliance flue outlet) and – using the
same screws – install the air inlet plate (B).
●Usingtheholeintheexhaustconnectionmani-
foldasaguide,drilla3mmholeintheappliance
flue spigot and secure the exhaust manifold
connection to the flue spigot using the screw
provided (C).
●Using the two holes in the air inlet plate as a
guide, drill a 3mm hole in each and secure the
air inlet pipe/bend using the screws provided.
●Thetwinfluepipesextensionsandaccessories
can now be installed by pushing together (the
plain end of each extension or bend should be
pushed approximately 50mm into the female
socket of the previous piece).
Total flue length Restrictor required
Less than 5.0 metres 50mm diameter
Lessthan 10.0metres notrequired
35
NOTE
Before cutting twin flue pipes ensure allowances
have been made for connection onto the previous
piece and onto the concentric to twin converter.
Thelasttwinfluepipesmustbepushed50mmonto
themalespigotsoftheconcentrictotwinconverter.
NOTE
You must ensure that the entire flue system is
properly supported and connected.
Seal the flue terminal assembly to the wall using
cement or a suitable alternative that will provide
satisfactory weatherproofing. The interior and
exterior trim can now be fitted.
4.5.3.3 VERTICAL TERMINATION (see fig. 13)
The twin flue system must be converted to the
dedicated concentric flue kit for termination.
●The vertical terminal is supplied with a built-in
converter box and cannot be shortened.
●A 130mm hole is required for the passage of
theconcentric terminal throughthe ceilingand/
or roof.

Supplied By www.heating spares.co Tel. [phone]
14
Depending on site conditions it may be prefer-
able to install the terminal assembly prior to fit-
ting the twin flue pipes.
Fit the appropriate flashing plate to the roof and
insert the vertical flue terminal through the flash-
ing plate from the outside, ensuring that the col-
lar on the flue terminal fits over the flashing.
Push-fit the twin flue pipes onto the concentric
to twin converter ensuring that the exhaust pipe
connects to the exhaust connection on the con-
centric to twin converter.
If necessary cut the plain ends (male) of the twin
flue pipes to allow connection to the concentric
to twin converter.
NOTE
●Before cutting twin flue pipes ensure allow-
anceshavebeenmade for connectiononto the
previous piece and onto the concentric to twin
converter. The last twin flue pipes must be
pushed50mmonto themalespigots ofthecon-
centric to twin converter.
●You must ensure that the entire flue system is
properly supported and connected.
●Ensurethatanyhorizontalsectionsofpipehave
aminimum 1ºfall towardstheappliance(17mm
per 1000mm).
4.6 CONNECTING THE GAS AND WATER
Theapplianceissuppliedwithanaccessorypack
that includes service valves.
The service valves are of the compression type.
Theaccessorypackcontainssealingwashers’etc,
for use with the service valves. When connecting
pipe work to the valves, tighten the compression
end first then insert the sealing washers before
tightening the valve to the appliance.
NOTE
It will be necessary to hold the valve with one
spanner whilst tightening with another
4.6.1 GAS (fig. 6 & 14)
The appliance is supplied with a 15mm service
valve, connect a 15mm pipe to the inlet of the
valve and tighten both nuts.
NOTE
It will be necessary to calculate the diameter of
the gas supply pipe to ensure the appliance has
an adequate supply of gas.
4.6.2 FLOW & RETURN (fig. 6 & 14)
The appliance is supplied with 22mm service
valves for the flow and return connections, con-
nect a 22mm pipe to the inlet of each valve and
tighten both nuts.
NOTE
Depending on system requirements, it may nec-
essary to increase the size of the flow & return
pipe work after the service valve connections.
4.6.3 COLD WATER INLET (fig. 6 & 14)
Theapplianceissuppliedwitha15mmstopcock,
connect a 15mm pipe to the inlet of the stopcock
and tighten both nuts.
4.6.4 HOT WATER OUTLET (fig. 6 & 14)
The appliance is supplied with a 15mm outlet
connection, connect a 15mm pipe to the outlet
connection and tighten both nuts.
4.6.5 SAFETY VALVE (fig. 6 & 14)
Connect the safety valve connection pipe to the
safety valve outlet and tighten. The discharge
pipe must have a continuous fall away from the
appliancetooutsideandallowany watertodrain
away thereby eliminating the possibility of freez-
ing. The discharge pipe must terminate in a
position where any water - possibly boiling -
discharges safely without causing damage or
injury, but is still visible.
4.6.6 CONDENSE PIPE (fig. 6 & 14)
Duringnormaloperationtheboilerproducescon-
dense which is collected in a trap located in the
lowerpartof theboiler.A flexiblepipe(condense
outlet pipe) is connected to the outlet of the trap.
The flexible pipe must be connected to a plastic
waste pipe only. The plastic waste pipe must
haveaminimumofa3ºfalltowardsthedrain.Any
external run of pipe should be insulated to pre-
vent the risk of freezing.
CONNECTING THE CONDENSATE OUTLET
Gently pull the condense outlet pipe down from
its location inside the boiler until approximately it
protrudes from the underside of the boiler. Con-
nect a suitable plastic (not copper) pipe (no less
than 21mm diameter) to the outlet pipe and
ensure it discharges in accordance with local
building regulations or other rules in force.
4.7 ELECTRICAL CONNECTIONS
Theboilerissuppliedwitha2-metrefly-lead.This
lead can be used for connection to the electrical
supply. Connect the fly-lead to a fused plug or
fused isolator in the following way:
●brown wire to LIVE supply
●blue wire to NEUTRAL supply
●green/yellow to EARTH connection.
Insert the supplied 3-AMP fuse into the fused
isolator or fused plug.
Should the fly-lead be unsuitable, refer to 4.7.3
fordetailsonhowtoconnecttheelectricalsupply
directly to the boiler.
The electrical supply must be as specified in
section 3/3A. A qualified electrician should con-
nect the appliance to the electrical supply. If
controls-externaltotheappliance-arerequired,
a competent person must undertake the design
of any external electrical circuits, please refer to
section 8 for detailed instructions. ANY EXTER-
NALCONTROLORWIRINGMUSTBESERVED
Fig. 14
flow return gas DHW
outlet DHW inlet
condense
safety
valve drain

Supplied By www.heating spares.co Tel. [phone]
15
FROM THE SAME ISOLATOR AS THAT OF
THE APPLIANCE. The supply cable from the
isolator to the appliance must be 3-core flexible
sized0.75mmtoBS6500orequivalent.Wiringto
the appliance must be rated for operation in
contact with surfaces up to 90 ºC.
4.7.1 CASING REMOVAL
Togain internal accesstothe applianceyoumust
first remove the casing, proceed as outlined be-
low:
●locate and unscrew the 3-screws (A) that se-
cure the outer casing to the appliance (see fig.
15)
●lift the casing upward to disengage it from the
top locating hooks and then remove
●store the casing and screws safely until re-
quired. Re-fit in the reverse order
●gently lower the control fascia until it rests.
4.7.2 APPLIANCE TERMINAL BLOCK
The appliance terminal block is located on the
left side of the control fascia (see fig.15).Locate
and remove the screw that secures the terminal
block cover.
NOTE
The appliance comes with a factory fitted clock
toallow basicoperation of theboiler.If it isantici-
pated that additional controls - such as a room
thermostat - will be required please refer to the
wiring diagrams in section 8 for more detailed
information.
4.7.3 CONNECTINGTHE MAINS (230V) INPUT (see
fig. 16)
Liftthe terminalblockcover asdescribed in4.7.2.
Passthe cable throughthecableanchoragepoint.
At the terminal block on the extreme left, there
are 3 terminals from left to right they are:
LIVE
NEUTRAL
EARTH
Connect the supply cable wires (LIVE, NEU-
TRAL&EARTH)totheircorrespondingterminals
on the appliance terminal block (see fig. 17).
Ensurethat theEARTH wireis leftslightly longer
than the others, this will prevent strain on the
EARTH wire should the cable become taut.
Control panel screws and casing screws
Fig. 15
A
Fig. 16
The securing screw on the cable anchorage
should now be tightened. This must be done
before the control fascia is re-fitted in the upright
position. The appliance casing and screws can
now be re-fitted.
Fig. 17

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16
5.1 GAS SUPPLY INSTALLATION
Inspect the entire installation including the gas
meter,testforsoundnessandpurge.RefertoBS
6891 for specific instruction.
5.2 THE HEATING SYSTEM
The appliance contains components that may
becomedamagedorrenderedinoperableby oils
and/or debris that are residual from the installa-
tion of the system, consequently it is essential
thatthesystembeflushedinaccordancewiththe
following instructions.
5.3 INITIAL FILLING OF THE SYSTEM
Ensure both flow and return service valves are
open, remove appliance casing as described in
4.7.1,identifytheautomaticairreleasevalveand
loosen the dust cap by turning the cap anti-
clockwise one full turn. IMPORTANT, THERE
ARE NO MANUAL AIR RELEASE VALVES LO-
CATEDONTHEAPPLIANCE.Ensureallmanual
air release valves located on the heating system
areclosed.Connectthefillingloop(notsupplied)
and slowly proceed to fill the system. As water
enters the system the pressure gauge will begin
torise.Oncethegaugehasreached1BARclose
the filling loop and begin venting all manual air
release valves, starting at the lowest first. It may
benecessarytogobackandtop-upthepressure
untiltheentiresystemhasbeenfilled. Inspectthe
systemforwatersoundness,rectifyinganyleaks.
5.4 INITIAL FLUSHING
Thewholeoftheheatingsystemmustbeflushed
both cold and hot as detailed in 5.8. Open all
radiatoror heating valvesand the applianceflow
& return service valves. Drain the boiler and
system from the lowest points. Open the drain
valve full bore to remove any installation debris
from the boiler prior to lighting. Refill the boiler
and heating system as described in 5.3.
5.5 FILLING THE HOT WATER SYSTEM
Close all hot water outlets, turn appliance stop-
cockto thenormaloperating position(fully coun-
ter clockwise), slowly open each outlet until air
hasbeenexpelledandclearwaterisdischarged.
Check pipe-work etc. for water soundness.
5.6 PRE-OPERATION CHECKS
Before attempting the initial lighting of the appli-
ance, the following checks must be carried out:
●ensureall gas servicevalves fromthe meterto
theapplianceareopenandthesupplypipehas
been properly purged
●ensure the proper electrical checks have been
carried out, (see 7.7) particularly continuity,
polarity, and resistance to earth
●ensure the 3 AMP fuse – supplied with the
appliance – has been fitted.
●ensurethe systemhasbeenfilled,vented,and
the pressure set to 1 BAR.
●ensurethefluesystemhasbeenfittedproperly
and in accordance with the instructions
●ensure all appliance service valves are open.
SECTION 5 COMMISSIONING
5.7 INITIAL LIGHTING
Ensure the electrical supply to the appliance is
switched on. Move the selector switch to the
Heating & Hot Water position, ensure the time
clock is switched to an ‘ON’ position and ensure
any other external controls (room thermostat for
example) are also calling for heat.
The appliance will now operate in the mode as
described in 1.2. Should the appliance fail to
ignite, refer to 5.6 and/or section 7 (faultfinding).
5.7.1 CHECKING THE BURNER PRESSURE
Although the burner pressure is factory set, it is
necessary to check it during commissioning.
Isolate the appliance from the electrical supply
andattachasuitablemanometertothegasvalve
outlet test-point (see fig. 18). Light the boiler as
describedin 5.7, turnthe HotWater temperature
selector to maximum, and open fully a DHW
outlet (preferably the bath), allowing the appli-
ance to stabilise. Compare the reading on the
manometer with the value described in 2.3. If
adjustment is required, follow the detailed in-
structions in section 7 (7.3).
Once the burner pressure has been checked,
close the DHW outlet, isolate the appliance from
theelectrical supply, remove themanometer, and
tighten the gas valve outlet test nipple.
5.8 FINALFLUSHINGOFTHEHEATINGSYSTEM
The system shall be flushed in accordance with
BS 7593. Should a cleanser be used, it must be
suitableforCopperandAluminiumheatexchang-
ers.Itshallbefromareputablemanufacturerand
shall be administered in strict accordance with
the manufacturers’ instructions and the DWTA
code of practice.
5.8.1 INHIBITORS
See section 3 “General requirements”.
5.9 SETTING THE BOILER OPERATING TEM-
PERATURE
The flow outlet temperature can be adjusted
between 40ºC - 80ºC via the Heating thermostat
knob (see fig.1).
Fig. 18
Protective
cap
Outlet
test-point
Inlet
test-point

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5.9.1 SETTING THE DOMESTIC HOT WATER TEM-
PERATURE
The DHW outlet temperature can be adjusted
between 40ºC - 65ºC via the Hot Water thermo-
stat knob (see fig.1).
5.10 SETTING THE SYSTEM DESIGN PRESSURE
The design pressure should be a minimum of 1
BAR and a maximum of 1.5 BAR.
The actual reading should ideally be 1BAR plus
the equivalent height in metres (0.1 BAR = 1
metre) to the highest point in the system above
the base of the appliance (up to the maximum of
1.5 BAR total).
N.B. The safety valve is set to lift at 3 BAR/30
metres/45 psig.ee fig.1).
To lower the system pressure to the required
value, water can be drained from the heating
system drain cock or from the boiler drain cock.
5.11 REGULATING THE HOT WATER
The appliance is fitted with a flow rate restrictor
that limits the maximum flow rate that can be
drawn through the appliance.
The restrictor eliminates the need to manually
adjust the DHW flow rate. However if it is felt
necessary to further increase or decrease the
availableflow rate,sparerestrictors areincluded
in the accessory pack.
The spare flow rate restrictors can be fitted to
either increase or decrease the maximum flow
rate.Thetablesabovedenotethesizeofrestrictor
fitted and the spare restrictors supplied in the
accessory pack. Each restrictor is colour-coded
to enable identification.
5.11.1 CHANGING THE FLOW RESTRICTOR
Referto6.19for detailedinstructiononchanging
the flow restrictor.
5.11.2 REGULATINGTHE CENTRAL HEATINGSYS-
TEM
Fully open all radiator and circuit valves and run
theappliancefor bothheatingand hotwateruntil
heatedwateriscirculating.Ifconditionsarewarm
remove any thermostatic heads. Adjust radiator
returnvalvesandanybranchcircuitreturnvalves
until the individual return temperatures are cor-
rect and are approximately equal.
5.12 FINAL CHECKS
●ENSURE ALL TEST NIPPLES ON THE AP-
PLIANCE GAS VALVE HAVE BEN TIGHT-
ENED AND CHECKED FOR SOUNDNESS.
●ENSURE THE APPLIANCE FLUE SYSTEM
ISFITTED CORRECTLYAND ISPROPERLY
SECURED.
●ENSURE ALL PIPE WORK IS RE-CHECKED
FOR SOUNDNESS.
●RE-FIT APPLIANCE CASING.
●COMPLETE BENCHMARK CHECKLIST.
FOR UK ONLY
Complete details of the boiler, controls, installa-
tionand commissioninginthe Benchmarkcheck-
list at the back of this book. It is important that
the Benchmark checklist is correctly completed
and handed to the user. Failure to install and
commission the appliance to the manufacturers
instructions may invalidate the warranty.
5.13 INSTRUCTING THE USER
Hand over all documentation supplied with this
appliance - including these instructions - and
explaintheimportance ofkeeping them ina safe
place.
Explain to the user how to isolate the appliance
from the gas, water and electricity supplies, and
the locations of all drain points.
Show the user how to operate the appliance and
any associated controls correctly.
Showthe userthelocation ofthefilling valveand
howtotop-upthesystempressurecorrectly,and
showthelocationofallmanualairreleasepoints.
Explain to the user how to turn off the appliance
forbothlongand shortperiodsandadviseon the
necessary precautions to prevent frost damage.
Explain to the user that for continued safe and
efficient operation, the appliance must be serv-
iced annually by a competent person.
8-litre(White) 9-litre(Orange) 10-litre(Blue)
Fitted Spare Spare
25
9-litre(Orange) 10-litre(Blue) 11-litre(Beige)
Spare Fitted Spare
29
11-litre(Beige) 12-litre(Red) 13-litre(Olive)
Spare Fitted Spare
35

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SECTION 6 SERVICING INSTRUCTIONS
6.1 GENERAL
Toensurethecontinuedsafeandefficientopera-
tion of the appliance, it is recommended that it is
checked and serviced at regular intervals.
To ensure correct and safe operation of the
appliance, it is essential that any worn or failed
component be replaced only with a genuine
Vokera spare part.
The frequency of servicing will depend upon the
particular installation conditions, but in general,
once per year should be adequate.
It is the law that any servicing work is carried out
bycompetent personsuch asaVokera engineer,
an approved service agent, British Gas, CORGI
registered personnel or other suitably qualified
personnel.
The following instructions apply to the appliance
and its controls, but it should be remembered
that the central heating and the domestic hot
water systems would also require attention from
time to time.
6.2 ROUTINE ANNUAL SERVICING
Checktheoperation oftheapplianceandensure
it functions as described in section 7. Compare
the performance of the appliance with its design
specification. The cause of any noticeable dete-
riorationshouldbeidentifiedandrectifiedwithout
delay.
Thoroughly inspect the appliance for signs of
damage or deterioration especially the flue sys-
tem and the electrical apparatus.
Check and adjust - if necessary - all burner
pressure settings (see section 7.3).
Check and adjust - if necessary - the system
design pressure (see section 5.10).
Carry out an analysis of the flue gases (see 7.4)
and visually check the condition of the entire flue
assembly. Compare the results with the appli-
ance design specification. Any deterioration in
performancemustbeidentifiedandrectifiedwith-
out delay.
Ensurebothflueventurisarecleanand freefrom
any debris or obstruction.
Ensure the burner, main heat exchanger and
latent heat collector are clean and free from any
debris or obstruction.
6.3 REPLACEMENT OF COMPONENTS
Although it is anticipated that this appliance will
giveyearsofreliable,troublefreeservice,thelife
spanofcomponentswillbedeterminedbyfactors
such as operating conditions and usage. Should
the appliance develop a fault, the fault finding
section will assist in determining which compo-
nent is malfunctioning.
6.4 COMPONENT REMOVAL PROCEDURE
Toremoveacomponent,accesstotheinteriorof
the appliance is essential. Isolate the appliance
from the electrical supply and remove the fuse.
And when necessary, close all service valves on
the appliance, remove the appliance casing as
described in section 4.7.1 and drain the water
content from the appliance via the drain valve
located at the front of the hydraulic section using
thetubeprovided.Ensuresomewaterabsorbent
cloths are available to catch any residual water
that may drip from the appliance or removed
component. Undertake a complete commission-
ingcheck asdetailed insection 5,after replacing
any component. ALWAYS TEST FOR GAS
SOUNDNESS IF ANY GAS CARRYING COM-
PONENTS HAVE BEEN REMOVED OR DIS-
TURBED.
6.5 PUMP ASSEMBLY fig. 19
Carry out component removal procedure as de-
scribed in 6.4.
The pump head can be replaced by disconnect-
ing the electrical connection at the pump and
removingthe4-Allenscrewsthatsecurethehead
to the pump base. Alternatively, the complete
pump assembly can be removed as follows:
●disconnect the electrical connection from the
pump control box
●locate and remove the pressure gauge secur-
ingpinanddisconnectthepressuregaugefrom
the pump assembly
●locateandremovetheexpansionpipesecuring
pinanddisconnecttheexpansionpipefromthe
pump assembly
●locate and remove the condense pipe located
between the air-chamber and condense trap
●refertofig.19,disconnectandremoveitemsA,
B & C
●locate and remove securing pin ‘F’ and lift the
pump assembly away from the hydraulic sec-
tion.
Replace in the reverse order.
6.6 SAFETY VALVE fig. 20
Carry out component removal procedure as de-
scribed in 6.4.
Disconnect and remove the safety valve outlet
pipe. Locate and remove the safety valve secur-
ing pin (B). The safety valve can now be re-
moved. Replace in the reverse order.
Fig. 19
A
B
C
F
G