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