VOKERA Compact A Release note

Installation
& Servicing
Instructions
THESE INSTRUCTIONS
TO BE RETAINED
BY USER
Compact

Contents
Design principles and operating sequence Page
1.1 Principle components 2
1.2 Central heating mode 2
1.3 Hot water mode 2
1.4 Safety devices 2
1.5 Frost protection 2
Technical data Page
2.1 Central heating 3
2.2 Domestic hot water 3
2.3 Gas pressure 3
2.4 Expansion vessel 3
2.5 Dimensions 3
2.6 Clearances 3
2.7 Connections 3
2.8 Electrical 3
2.9 Flue details 3
2.10 Efficiency 3
2.11 Pump duty 4
General requirements (UK) Page
3.1 Related documents 5
3.2 Location of appliance 5
3.3 Gas supply 5
3.4 Flue system 5
3.5 Air supply 5
3.6 Water circulation 5
3.6.1 Pipework 6
3.6.2 Automatic by-pass 6
3.6.3 Drain cocks 6
3.6.4 Air release points 6
3.6.5 Expansion vessel 6
3.6.6 Filling point 6
3.6.7 Low pressure sealed system 6
3.6.8 Frequent filling 6
3.7 Electrical supply 6
3.8 Showers 6
3.9 Mounting on a combustible surface 7
3.10 Timber framed building 7
3.11 Inhibitors 7
General requirements (EIRE) Page
3.A1 Related documents 7
3.A2 Location of appliance 7
3.A3 Gas supply 7
3.A4 Flue system 7
3.A5 Air supply 8
3.A6 Water circulation 8
3.A6.1 Pipework 8
3.A6.2 Automatic by-pass 8
3.A6.3 Drain cocks 8
3.A6.4 Air release points 8
3.A6.5 Expansion vessel 8
3.A6.6 Filling point 8
3.A6.7 Low pressure sealed system 8
3.A6.8 Frequent filling 8
3.A7 Electrical supply 8
3.A8 Showers 8
3.A9 Mounting on a combustible surface 8
3.A10 Timber framed building 8
3.A11 Inhibitors 8
3.A12 Declaration of conformity 8
Installation Page
4.1 Delivery 9
4.2 Contents 9
4.3 Unpacking 9
4.4 Preparation for mounting the appliance 9
4.4.1 Important 9
4.4.2 Flue restrictor ring 9
4.5 Fitting the flue 9
4.5.1 Concentric horizontal flue 9
4.5.2 Concentric vertical flue 11
4.5.3 Twin flue system 11
4.6 Connecting the gas and water 13
4.6.1 Gas 13
4.6.2 Flow and return 14
4.6.3 Safety valve 14
4.6.4 Cold water inlet 14
4.6.5 Hot water outlet 14
4.7 Electrical connections 14
4.7.1 Casing removal 14
4.7.2 Electrical connection 14
4.7.3 Connecting the mains (230V) input 15
Commissioning Page
5.1 Gas supply installation 16
5.2 The heating system 16
5.3 Initial filling of the system 16
5.4 Initial flushing 16
5.5 Filling the hot water system 16
5.6 Pre-operation checks 16
5.7 Initial lighting 16
5.8 Checking burner pressures 16
5.9 Final flushing of the heating system 17
5.9.1 Inhibtors 17
5.10 Setting the flow temperature 17
5.11 Setting the system design pressure 17
5.12 Regulating the central heating system 17
5.13 Regulating the domestic hot water 17
5.14 Final checks 17
5.15 Instructing the user 17
Servicing instructions Page
6.1 General 18
6.2 Routine annual servicing 18
6.3 Replacement of components 18
6.4 De-scaling main heat exchanger 18
6.5 Component removal procedure 18
6.6 Pump head 18
6.7 Safety valve 18
6.8 Automatic air release valve 19
6.9 Water pressure switch 19
6.10 Domestic water flow switch 19
6.11 Pressure gauge 19
6.12 Primary and secondary thermistors 19
6.13 High limit thermostat 19
6.14 PCB 20
6.15 Integral time switch 20
6.16 Gas valve 20
6.17 Burner, injectors and spark/sense electrode 20
6.18 Flue fan 21
6.19 Heat exchanger 21
6.20 Air pressure switch 21
6.21 Expansion vessel 21
6.22 Expansion vessel (removal) 21
Checks, adjustments and fault finding page
7.1 Checking appliance operation 22
7.2 At rest mode 22
7.3 Hot water mode 22
7.4 Heating mode 22
7.5 Frost protection mode 22
7.6 Burner pressure settings 22
7.6.1 Setting the maximum DHW gas pressure 23
7.6.2 Setting the minimum DHW gas pressure 23
7.6.3 Setting the max & min CH burner pressures 23
7.7 Combustion analysis test 23
7.8 Checking the expansion vessel 23
7.9 Electro-mechanical faults 23
7.10 Possible installation faults 24
7.11 Electrical checks 24
7.11.1 Earth continuity test 24
7.11.2 Short circuit test 24
7.11.3 Polarity check 24
7.11.4 Reversed polarity or supply fault 24
7.11.5 Resistance to earth check 24
7.11.6 Fuses 24
7.12 Fault finding 24-31
Wiring diagrams Page
8.1 Connection of a room thermostat 32
8.2 Connection of an external time clock 32
Functional flow diagram 33-34
Exploded diagrams Page
Table 1 35
Table 2 36
Table 3 37
Table 4 38
Table 5 39
L.P.G. instructions Page
10.1 Technical data 40
10.2 Related documents 40
10.3 Gas supply 40
10.4 Gas supply installation 40
10.5 Burner pressures 40
10.5.1 Setting the maximum DHW gas pressure 40
10.5.2 Setting the minimum DHW gas pressure 40
10.5.3 Setting the max & min CH burner pressures 40
REAR FLUE Page
11.1 Fitting the flue 41

1
Compact
INTRODUCTION
Fig.1 General Layout
1 Flue Analysis Test Point
2 Pressure Tube Negative
3 Fan Assembly
4 Heat Exchanger
5 Secondary thermistor
6 Combustion chamber
7 Burner
8 Expansion vessel
9 Water pressure switch
10 Domestic Hot Water Flow Switch
11 Gas Valve
12 Timeclock
13 CH position
14 Fault indicator led
15 Mode selector switch
16 DHW position
17 Pressure gauge
18 Safety valve
19 Pump
20 Auto air vent
21 Electrode
22 High limit thermistor
23 Primary thermistor
24 Air chamber (with cover removed)
25 Air pressure switch
26 Auto by pass (fig. 2)
27 Water flow restrictor (fig. 2)
TheVokera Compact range of appliances are combined
central heating and domestic hot water boilers, which –
bydesign –incorporates fullsequence electronicignition,
circulating pump, expansion vessel, safety valve,
pressuregauge,automatic by-pass,and mechanicaltime
clock.
Compactisproducedasaroomsealedappliance,suitable
forwall mounting applicationsonly. Compact isprovided
with a fan powered flue outlet with an annular co-axial
combustionair intakethat canbe rotated –horizontally –
through 360 degrees for various horizontal or vertical
applications, and can also be converted for use with a
rear flue outlet. Compact can also be used with the
Vokera twin flue system.
This appliance is designed primarily for use with sealed
systems; consequently it is not intended for use on an
open vented system.
Fig. 1
35
150 95
12
3
4
5
6
7
8
9
10
11
18
19
20
21
22
23
24
25
85
150

2Compact
SECTION 1 DESIGN PRINCIPLES AND OPERATING SEQUENCE
Fig. 2
1.1 PRINCIPLE COMPONENTS
●A fully integrated, electronic control board fea-
turing mode selection switch, full sequence-
electronicignition,temperaturecontrolsystem,
and appliance status indicator.
●A BI-thermal gas to water heat exchanger.
●A multi-functional gas valve.
●Two-stage, primary water pressure switch.
Integral pump, expansion vessel, pressure re-
liefvalve,pressuregauge,domesticwaterflow
switch,fan,differentialairpressureswitch,and
time clock.
MODES OF OPERATION
1.2 CENTRAL HEATING MODE
Whenthereisarequestforcentralheatingviathe
time-clockand/oranyexternalcontrols,thepump
andfanarestarted,thefanprovesthedifferential
airpressureswitchwhichin-turn,allowsanignition
sequence to begin.
Ignition is sensed by the electronic circuitry to
ensure flame stability at the burner. Once suc-
cessfulignition hasbeenachieved theappliance
operatesal75% ofmaximumfor afifteen-minute
period, and thereafter the appliance operates on
maximum output until the desired temperature
setting is reached.
Once the desired temperature is reached, the
burner will modulate to maintain that tempera-
ture, however should the temperature within the
appliance continue to rise, the burner will shut
down and the boiler will perform a three-minute
anti-cycle (timer delay).
1.3 HOT WATER MODE
When there is a demand for domestic hot water
the domestic hot water flow switch is proved by
the flow of water through the appliance, this
allows the fan to run, the fan proves the differen-
tial air pressure switch which in-turn, allows an
ignition sequence to begin.
Ignition is sensed by the electronic circuitry to
ensure flame stability at the burner. Once
successful ignition has been achieved the appli-
ance will modulate burner gas pressure to main-
tain the desired water temperature, should the
temperature of the domestic hot water exceed
the temperature setting by 5 ºC the burner will
shut down until the water temperature drops
below the required setting.
1.4 SAFETY DEVICES
In both central heating and domestic hot water
modes, safe operation is ensured by.
●A water pressure switch that monitors the sys-
tempressure andwill deactivatethe pumpand
prevent burner ignition should the pressure or
primaryflowratefall belowtheratedtolerance.
●Differential air pressure switch that checks the
correct operation of the fan and flue thereby
preventing or interrupting burner operation.
●A high limit thermostat that overrides the con-
trolcircuittopreventorinterruptburnerignition.
●Asafetyvalvewhichreleasesexcesspressure
from the primary circuit.
1.5 FROST PROTECTION
The appliance has built-in frost protection that
allows the pump to operate if the appliance tem-
perature drops to 7 ºC, should the temperature
continue to drop the burner will light until the
primary circuit temperature exceeds 30 ºC.
return flow hw
outlet cold inlet
27
5
9
10
26
19
8
23
4
20
18

3
Compact
SECTION 2 TECHNICAL DATA
Ref. Condition 15 °C , 1013,25 mbar, dry gas
NOTE: L.P.G. data refer to section 10
Compact 24 Compact 28
2.1 Central heating
Heat input (kW) 26.3 31.0
Heat output (maximum) kW 24.0 28.0
Heat output (minimum) kW 9.4 10.5
Minimum working pressure 0,5 bar 0,5 bar
Maximum working pressure 3.0 bar 3.0 bar
Minimum flow rate 350 l/h 350 l/h
2.2 Domestic hot water
Heat input (kW) 26.3 31.0
Heat output (maximum) kW 24.0 28.0
Heat output (minimum) kW 8.2 8.7
Flow rate (35 °C rise) 9.8 l/min 11.5 l/min
Maximum inlet pressure 6.0 bar 6.0 bar
Minimum inlet working pressure 0.15 bar 0.15 bar
Minimum flow rate 2 l/min. 2 l/min.
2.3 Gas pressures
Inlet pressure G20 20.0 mbar 20.0 mbar
Maximum burner pressure 10.1 mbar 10.2 mbar
Minimum burner pressure (central heating) 1.9 mbar 1.9 mbar
Minimum burner pressure (domestic hot water) 1.5 mbar 1.3 mbar
Gross rate (maximum) 2.78 m3/h 3.28 m3/h
Injectors size 12 x 1.35 mm 14 x 1.35 mm
2.4 Expansion vessel
Capacity 8 litres 8 litres
Maximum system volume 76 litres 76 litres
Pre-charge pressure 1.0 bar 1.0 bar
2.5 Dimensions
Height 740 mm 740 mm
Width 400 mm 450 mm
Depth 328 mm 328 mm
Dry weight 34 kg 37 kg
2.6 Clearances
Left side 50 mm 50 mm
Right side 12 mm 12 mm
Top 150 mm from casing or 25 mm above flue elbow, whichever is applicable
Bottom 150 mm 150 mm
Front 600 mm 600 mm
2.7 Connections
Flow & return 22 mm 22 mm
Hot & cold water connections 15 mm 15 mm
Gas 15 mm 15 mm
Safety valve 15 mm 15 mm
2.8 Electrical
Voltage 230V/~ 50hz 230V/~ 50hz
Power consumption 125 W 125 W
Internal fuse 2 A 2 A
PCB fuse 2 AF 2 AF
External fuse 3 A 3 A
2.9 Flue details
Maximum horizontal flue length (concentric) 4.25 m 3.4 m
Maximum vertical flue length (concentric) 5 m 4.2 m
Maximum twin flue length (horizontal or vertical) 14 m + 14 m 14 m + 14 m
Maximum rear flue length (see section 11) 1.0 m 1.0 m
2.10 Efficiency
SEDBUK Band “D” Band “D”

4Compact
2.11 PUMP DUTY
Fig.3showstheflowrateavailable–after
allowing for pressure loss through the
appliance–againstsystempressureloss.
When using this graph apply only the
pressurelossofthesystem.Thegraphis
basedona20ºCtemperaturedifferential.
Fig. 3
Fig. 4
Water pressure (mbar)
Litres Per Hour (x100)
100
200
300
400
500
600
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400
SECTION 3 GENERAL REQUIREMENTS (UK)
Key Location Minimum distance
A Below an opening (window, air-brik, etc.) 300 mm
B Above an opening (window, air-brik, etc.) 300 mm
C To the side of an opening (window, air-brik, etc.) 300 mm
D Below gutter, drain-pipe, etc. 75 mm
E Below eaves 200 mm
F Below balcony, car-port roof, etc. 200 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 600 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 300 mm
Q From the top of the vertical terminal to the roof flashing As determined by the fixed collar
of the vertical terminal
.

5
Compact
This appliance must be installed by a competent
person in accordance with the Gas Safety
(Installation & Use) Regulations.
3.1 RELATED DOCUMENTS
Theinstallationofthisboilermustbeinaccordance
with the relevant requirements of the Gas Safety
(Installation&Use)Regulations,thelocalbuilding
regulations, the current I.E.E. wiring regulations,
the bylaws of the local water undertaking, the
Building Standards (Scotland) Regulation, and
Building Standards (Northern Ireland)
Regulations.
Itshould be inaccordance also withany relevant
requirementsofthelocalauthorityandtherelevant
recommendationsofthefollowingBritishStandard
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 in Scotland, theelectrical
provisions of the Building Regulations, with
respect to the installation of the appliance in a
roomorinternalspacecontainingabathorshower.
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.
Thelocationchosenfortheappliancemustpermit
the provision of a safe and satisfactory flue and
termination. The location must also permit an
adequate air supply for combustion purposes
and an adequate space for servicing and air
circulation around the appliance. Where the
installation 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/
cupboard may be utilised provided that it is
modified to suit.
Details of essential features of compartment/
cupboard design including airing cupboard
installationsaregiveninBS6798.Thisappliance
is not 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
soundness 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
Theterminalshouldbelocatedwherethedispersal
of combustion products is not impeded and with
dueregardforthedamageanddiscolorationthat
may occur to building products located nearby.
Theterminalmustnotbelocatedinaplacewhere
it is likely to cause a nuisance (fig. 4).
In cold and/or humid weather, water vapour may
condense on leaving the terminal; the effect of
such pluming must be considered.
BS 5440 PART 1 FLUES
BS 5440 PART 2 FLUES AND VENTILATION
BS 5449 PART 1 FORCED CIRCULATION HOT WATER SYSTEMS
BS5546 INSTALLATION OF GAS HOT WATER SUPPLIES FOR DOMESTIC PURPOSES
(2ND FAMILY GASES)
BS 6798 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 2 m 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.
Referto BS5440 Part 1,when theterminal is 0.5
metres(orless)belowplasticgutteringor1metre
(or less) below painted eaves.
3.5 AIR SUPPLY
The following notes are intended for general
guidance only.
Thisapplianceisaroom-sealed,fan-fluedboiler,
consequentlyit 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
required.
3.6 WATER CIRCULATION
Detailedrecommendations aregiven inBS 5449
Part 1 and BS 6798. The following notes are for
general guidance only.

6Compact
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 (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
indicativeof a leak. Care shouldbe taken during
the installation of the appliance to ensure all
aspectsofthesystemarecapableofwithstanding
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
completeisolationfromthesupply.Thepreferred
method is by using a double-pole switch with a
contact separation of at least 3 mm. The switch
must only supply the appliance and its
corresponding controls, i.e. time clock, room
thermostat, 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
andbesuitablefor usewithacombinationboiler.
3.6.1 PIPEWORK
ItisrecommendedthatcoppertubingtoBS2871
Part1isusedinconjunctionwithsolderedcapillary
joints.
Where possible pipes should have a gradient to
ensureairiscarriednaturallytoairreleasepoints
and that water flows naturally to drain cocks.
Exceptwhereprovidingusefulheat,pipesshould
beinsulatedtoavoidheatlossandinparticularto
avoidthepossibilityoffreezing.Particularattention
shouldbepaidtopipespassingthroughventilated
areas such as under floors, loft space, and void
areas.
3.6.2 AUTOMATIC BY-PASS
The appliance has a built-in automatic by-pass,
consequently there is no requirement for an
external by-pass, however the design of the
system should be such that it prevents boiler
‘cycling’.
3.6.3 DRAIN COCKS
Thesemust be located in accessible positions to
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 whereair islikely tobe 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 of expansion from within the system,
generally this is sufficient, however if the system
has an unusually high water content, it may be
necessary to provide additional expansion
capacity (see section 6.19).
3.6.6 FILLING POINT
A method for initial filling of the system and
replacingwaterlostduringservicingetc.mustbe
provided.This method offilling mustcomply with
the current Water Supply (Water Fittings)
Regulations 1999 and Water Bylaws 2000
(Scotland). Fig. 5 shows an accepted method.
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

7
Compact
Fig. 6
3.9 MOUNTING ON A COMBUSTIBLE SURFACE
If the appliance is to be fitted on a wall of
combustiblematerial,asheetoffireproofmaterial
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
Vokera recommend that a neutral inhibitor is
used to protect the heating system from the
effects of corrosion and/or electrolytic action.
The inhibitor must be administered in strict
accordancewiththemanufacturers*instructions.
*Fernox and Sentinel manufacture products that
have proved suitable for use with Vokera
appliances. VokeraLtd. cannot comment on the
suitability of any other such product with our
appliances.
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
Installations) Declaration (I.S. 813).
3A.1 RELATED DOCUMENTS
Theinstallationofthisboilermustbeinaccordance
withtherelevantrequirementsofthelocalbuilding
regulations, the current ETCI National Rules for
Electrical Installations, and the bylaws of the
local water undertaking.
Itshould be inaccordance also 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.
Whenanapplianceisinstalledinaroomorinternal
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.
Thelocationchosenfortheappliancemustpermit
the provision of a safe and satisfactory flue and
termination. The location must also permit an
adequate air supply for combustion purposes
and an adequate space for servicing and air
circulation around the appliance. Where the
installation 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
specifically for this purpose. An existing
compartment/cupboardmaybeutilisedprovided
that it is modified to suit.
This appliance is not suitable for external
installation.
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
soundness 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
Theterminalshouldbelocatedwherethedispersal
of combustion products is not impeded and with
dueregardforthedamageanddiscolorationthat
may occur to building products located nearby.
Theterminalmustnotbelocatedinaplacewhere
it is likely to cause a nuisance (see I.S. 813).
In cold and/or humid weather, water vapour may
condense on leaving the terminal; the effect of
such pluming must be considered.
If installed less than 2 m 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,whenthe terminalis0.5 metres
(or less) below plastic guttering or 1 metre (or
less) below painted eaves.
35
150 95
85
150

8Compact
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
required.
3A.6 WATER CIRCULATION
Specific recommendations are given in I.S. 813.
The following notes are for general guidance
only.
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
avoidthepossibilityoffreezing.Particularattention
shouldbepaidtopipespassingthroughventilated
areas such as under floors, loft space, and void
areas.
3A.6.2 AUTOMATIC BY-PASS
The appliance has a built-in automatic by-pass,
consequently there is no requirement for an
external by-pass, however the design of the
system should be such that it prevents boiler
‘cycling’.
3A.6.3 DRAIN COCKS
Thesemust be located in accessible positions to
facilitate draining of the appliance and all water
pipes connected to the appliance.
3A.6.4 AIR RELEASE POINTS
Thesemustbepositionedatthehighestpointsin
thesystem whereair islikely tobe 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
when the system is heated. It can accept up to 8
litres of expansion from within the system,
generally this is sufficient, however if the system
has an unusually high water content, it may be
necessary to provide additional expansion
capacity (see section 6.19).
3A.6.6 FILLING POINT
A method for initial filling of the system and
replacing water lost during servicing etc. has
beenprovided.Youshouldensurethismethodof
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 (fig. 5).
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
aspectsofthesystemarecapableofwithstanding
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
completeisolationfromthesupply.Thepreferred
method is by using a double-pole switch with a
contact separation of at least 3 mm. The switch
must only supply the appliance and its
corresponding controls, i.e. time clock, room
thermostat, etc.
3A.8 SHOWERS
Iftheapplianceisintendedforusewithashower,
the shower must be thermostatically controlled
andbesuitablefor usewithacombinationboiler.
3A.9 MOUNTING ON A COMBUSTIBLE SURFACE
If the appliance is to be fitted on a wall of
combustiblematerial,asheetoffireproofmaterial
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)‘GuideforGasInstallationsinTimberFrame
Buildings’ gives specific advice on this type of
installation.
3A.11 INHIBITORS
Vokera recommend that a neutral inhibitor is
used to protect the heating system from the
effectsofcorrosionand/orelectrolyticaction.The
inhibitormustbeadministeredinstrictaccordance
with the manufacturers* instructions.
*Fernox and Sentinel manufacture products that
have proved suitable for use with Vokera
appliances. Vokera Ltd. cannot comment on the
suitability of any other such product with our
appliances.
3A.12 DECLARATION OF CONFORMITY
A Declaration of Conformity (as defined in I.S.
813) must be provided on completion of the
installation.
A copy of the declaration must be given to the
responsiblepersonandalsotothegassupplierif
required.

9
Compact
SECTION 4 INSTALLATION
4.1 DELIVERY
The appliance is delivered in a heavy-duty card-
boardcarton. Laythe cartonon thefloor withthe
writing the correct way up.
4.2 CONTENTS
Contained within the carton is:
●the boiler
●the wall mounting bracket
●an accessories pack containing service valves
and sealing washers
●the instructions pack containing installation &
servicing instructions, appliance logbook, user
instructions,guaranteeregistrationcard,3amp
fuse and flue restrictor ring.
4.3 UNPACKING
At the top of the carton pull both sides open – do
notuseaknife–unfoldtherestofthecartonfrom
around the appliance, carefully remove all
protectivepackaging fromthe appliance,and lay
theaccessoriesetc.tooneside.Protectivegloves
shouldbeusedtolifttheappliance,theappliance
back-frame should be used for lifting points.
4.4 PREPARATION FOR MOUNTING THE
APPLIANCE
The appliance should be mounted on a smooth,
non-combustible,verticalsurface,whichmustbe
capable of supporting the full weight of the
appliance. Care should be exercised when
determining the position of the appliance with
respect to hidden obstructions such as pipes,
cables, etc.
When the position of the appliance has been
decided–usingthetemplatesupplied–carefully
mark the position of the wall bracket (fig. 7) and
flue-hole (if applicable).
4.4.1 IMPORTANT
There are three hole types set out on the
appliance template:
●type 1 should be used in conjunction with
the telescopic flue kits (part no. 0225705 &
0225710)
●type 2 should be used in conjunction with
standard horizontal flue kit (part no.
2359029)
●type 3 should be used in conjunction with
the telescopic rear flue kits (part no.
0225905 & 0225910).
4.4.2 FLUE RESTRICTOR RING
To ensure maximum efficiency of the appliance,
itmay be necessary to fitone of the supplied flue
restrictor rings to the appliance flue outlet.
4.5 FITTING THE FLUE
The top flue outlet permits both horizontal and
vertical flue applications to be considered,
alternatively, 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).
The appliance flue outlet elbow can be rotated
through 360º on its vertical axis. In addition the
fluemaybeextendedfromtheoutletelbowinthe
horizontal plane (see section 4.4.2), however if
theflue is to beextended or additionalbends are
to be fitted, the standard horizontal flue kit (part
no. 2359029) must be used. A reduction must
also be made to the maximum length (see table)
when additional bends are used.
Bend Reduction in maximum flue length for each bend
45º bend 0.5 metre
90º bend 0.85 metre
Using the template provided (see section 4.4.1),
mark and drill a 125 mm hole for the passage of
the flue pipe. The hole should have a 1º drop
from the boiler to outside, to eliminate the
possibilityof rainwater enteringthe appliance via
the flue.
The fixing holes for the wall-mounting bracket
shouldnowbedrilledandplugged,anappropriate
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.
Horizontal flue terminals and accessories
Part No. Description Min-Max Length
0225705 Standard telescopic flue 380 mm – 600 mm
(Dimension ‘X’)
0225710 Extended telescopic flue 600 mm – 920 mm
(Dimension ‘X’)
2359029 Horizontal flue kit
For use with add. Bends 833 mm
& extensions (dimension ‘X’)
2359069 750 mm extension 750 mm
2359079 1500 mm extension 1500 mm
2359049 45º bend (pair) N/A
2359059 90º bend N/A
0225760 Wall bracket (5) N/A
Total flue length Restrictor required
Less than 0.85 metre
Less than 2 metre
Less than 3 metre
Less than 4.25 metre
42 mm diameter
44 mm diameter
46 mm diameter
Not installed
Compact 24
Compact 28
Total flue length Restrictor required
Less than 0.85 metre
Less than 1.70 metre
Less than 2.70 metre
Less than 3.40 metre
45 mm diameter
47 mm diameter
49 mm diameter
Not installed

10 Compact
Carefullymeasurethedistancefromthecentreof
theapplianceflueoutlettothefaceofthe outside
wall (dimension ‘X’, fig. 8). Add 50 mm to
dimension ‘X’ to give the overall flue length
(dimension ‘Y’). Using the complete telescopic
flueassembly adjustthe length tosuit dimension
‘Y’. Once the telescopic flue terminal has been
adjusted to the correct length, secure the flue
assembly with the screw supplied.
Insert the flue restrictor ring (supplied in the
instructionpack)intotheappliancefluegasoutlet.
Slidetheflue assemblyintothe previouslydrilled
flue hole and locate the flue bend over the
appliance flue outlet. Push the flue bend down
over the appliance flue outlet and ensure the
correct seal is made. Pull the flue assembly
towardsand overthe fluebend –using atwisting
action–ensuringthecorrectsealismade.Check
that the terminal protrudes past the finished
outside wall by the correct length (115 mm).
NOTE
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 satisfactory
weatherproofing. The interior and exterior trim
can now be fitted.
FITTING THE STANDARD (2359029)
HORIZONTAL FLUE KIT (see section 4.4.1)
Carefully measure the distance from the centre
of the appliance flue outlet to the face of the
outside wall (dimension ‘X’, fig. 8A). Ensure the
inner (60 mm) pipe is fully inserted into the outer
(100 mm) pipe (when the inner pipe is fully
inserted, it stands proud of the outer pipe by 7.5
mm). Add 32 mm to dimension ‘X’ to give the
overall flue length (dimension ‘Y’).The standard
horizontal flue kit (part no. 2359029) is suitable
for a distance (dimension ‘Y’) of up to 865 mm.
NOTE
Dimension ‘Y’ is measured from the end of the
terminal to the end of the outer (100 mm) pipe.
The internal trim should be fitted to the flue pipe
before connection of the 90º bend.
Insert the flue restrictor ring (supplied with
instructionpack) intothe applianceflue gasoutlet
if the total flue length is less than 1.0 metre.
If the horizontal flue kit (2359029) requires to be
cut to the correct size (dimension ‘Y’), you must
ensure that the inner (60 mm) pipe stands proud
of the outer (100 mm) pipe by 7.5 mm (fig. 8B).
Ensure any burrs are filed or removed and that
any seals are located properly before assembly.
Connect the inner (60 mm) pipe of the terminal
assembly to the push-fit end of the 90º bend
(supplied) using a twisting action. Insert the
assembled flue into the previously drilled hole.
Using the clips & screws supplied, connect the
flue assembly to the boiler, ensuring that the
terminal protrudes past the finished outside wall
by the correct length (135 mm).
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
satisfactory weatherproofing. The exterior trim
can now be fitted.
EXTENDING THE HORIZONTAL FLUE
If the horizontal flue requires extension/s or
additional bend/s, the standard horizontal flue
terminal (2359029) must be used. Connect the
bend – supplied with the terminal kit – to the top
of the boiler using the clips, screws & gaskets
supplied.Theadditionalbends&extensionshave
an internal push-fit connection, care should be
taken to ensure that the correct seal is made
when assembling the flue system. Connect the
required number of flue extensions or bends (up
tothemaximumequivalentfluelength)totheflue
terminalusingtheclips,screws&gasketssupplied
(fig. 8A & 8B).
type 1= centre of rear flue hole
using only 0225705 or
0225710 flue
type 2= centre of rear flue hole
for use with 2359029
type 3= for rear flue only
Fig. 8
“X” + 50 mm = “Y”
115 mm Fig. 8A
Dimension “Y”
Dimension “X”
Max 833 mm
135 mm
7,5
110
Fig. 7
Total flue length Restrictor required
Less than 1 metre Compact 24 Compact 28
40 mm diameter 42 mm diameter
FITTING THE TELESCOPIC FLUE KIT
(0225705 & 0225710)
3
2
1

11
Compact
Fig. 9
465 mm
300 mm
min.
150 mm
NOTE
When cutting the horizontal flue terminal or an
extensiontothe requiredlength, youmust ensure
that the excess is cut from the plain end of the
terminalor extension, and thatthe inner (60mm)
pipe is 7.5 mm longer than outer (100 mm) pipe
(fig.8A & 8B).Remove any burrs, andcheck that
any seals are located 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
satisfactory weatherproofing. The interior and
exterior trim can now be fitted.
4.5.2 CONCENTRIC VERTICAL FLUE
Theverticalflueterminalcanbeconnecteddirectly
to the appliance flue outlet. Alternatively, an
extension or bend can be connected to the
applianceflueoutletifdesired(seesection4.4.2),
howeverifadditionalbendsarefitted,areduction
must be made to the maximum flue length (see
table below).
Using the dimensions given in fig. 9 as a reference,
markandcuta105mmholeintheceilingand/orroof.
Fig. 8B
Boiler
Push-fit connection
Extension
7,5 mm
Fit the appropriate flashing plate to the roof and
inserttheverticalflueterminalthroughtheflashing
platefromtheoutside, ensuringthatthecollaron
the flue terminal fits over the flashing.
The fixing holes for the wall-mounting bracket
shouldnowbedrilledandplugged,anappropriate
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;therefore itmaybenecessary
toadjustthe heightof theappliance tosuit oruse
a suitable extension.
Insert the flue restrictor ring into the appliance flue
outlet,inaccordancewiththetableinsection4.4.2.
Connect the vertical flue assembly to the boiler
flue spigot using the 60 mm & 100 mm clips,
gaskets,&screws(supplied),ensuringthecorrect
seal is made. The flue support bracket (supplied
with the vertical flue kit) can now be fitted.
Iftheverticalfluerequiresextension/soradditional
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 (fig. 8B).
NOTE
Whencutting anextension tothe required length,
you must ensure that the excess is cut from the
plain end of the extension and that the inner (60
mm) pipe is 7.5 mm longer than outer (100 mm)
pipe (fig. 8B). Remove any burrs, and check that
any seals are located properly.
You must ensure that the entire flue system is
properly supported and connected.
Total flue length Restrictor required
Less than 1.5 metre
Less than 2.5 metre
Less than 3.5 metre
Less than 5 metre
42 mm diameter
44 mm diameter
46 mm diameter
Not installed
Compact 24
Compact 28
Total flue length Restrictor required
Less than 1.5 metre
Less than 2.4 metre
Less than 3.4 metre
Less than 4.2 metre
45 mm diameter
47 mm diameter
49 mm diameter
Not installed
4.5.3 TWIN FLUE SYSTEM
Compact 24
Total flue length (air = fumes) Restrictor required
Less than 4.5 + 4.5
Less than 10.5 + 10.5
Less than 14 + 14
42 mm diameter
44 mm diameter
46 mm diameter
Bend Reduction in maximum flue length for each bend
45º bend 0.5 metre
90º bend 0.85 metre
Part No. Description Length
2359039 Vertical flue terminal 1.0 metre
0225770 Pitched roof flashing plate N/A
0225765 Flat roof flashing plate N/A
2359069 750 mm extension 750 mm
2359079 1500 mm extension 1500 mm
2359049 45º bend (pair) N/A
2359059 90º bend N/A
0225760 Wall bracket (5) N/A
Vertical flue terminal and accessories

12 Compact
4.5.3.2 INSTALLATION OF CONDENSATE DRAIN KIT
(fig. 10B)
Thecondensatedrainkitmustbefittedwithin1metre
of the appliance flue outlet. It is recommended that
thecondensatedrainkitshouldbefittedinthevertical
plane, however it can be fitted horizontally with care.
●Fit the first bend to the condensate drain kit or
exhaust connection manifold by firmly pushing
in to position.
●Using the two holes in the exhaust connection
manifold as a guide, drill a 3 mm hole in each
and secure using the screws provided.
●Connect the air inlet pipe to the air baffle as above.
●Thetwin fluepipes extensionsand accessories
can now be installed by pushing together (the
plain end of each extension or bend should be
pushed approximately 50 mm into the female
socket of the previous piece).
The condensate drain trap must be connected
to the drain in accordance with building
Regulations or other rules in force.
Compact 28
Total flue length Restrictor required
Less than 4 + 4
Less than 8 + 8
Less than 12.5 + 12.5
Less than 14 + 14
45 mm diameter
47 mm diameter
49 mm diameter
Not required
TheVokeratwin fluesystem enablesgreaterflue
distances to be achieved (see section 2.8) than
thatof the standardconcentric fluesystem. It can
be used for horizontal or vertical applications,
however the twin flue system must be converted
tothededicated concentricflue kitfortermination.
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
INSTALLATION
●The flue must have a fall back of 1º back to the
appliance to allow any condensate that forms
in the flue system to drain. Consideration must
also be given to the fact that there is the
possibility of a small amount of condensate
dripping from the terminal.
●Ensurethat theentireflue systemis adequately
supported, use at least one bracket for each
extension.
●Extreme care must be taken to ensure that no
debris is allowed to enter the flue system at
any time.
●As the exhaust outlet pipe can reach very high
temperatures it must be protected to prevent
persons touching the hot surface.
Twin flue accessories
Part No. Description Length
0225805 Horizontal flue terminal 1.0 metre
0225810 Vertical flue terminal 1.0 metre
300 Twin adapter kit for Compact 24 N/A
2359249 Twin adapter kit for Compact 28 N/A
0225770 Pitched roof flashing plate N/A
0225765 Flat roof flashing plate N/A
0225815 Condensate drain kit N/A
0225820 0.25 m extension (pair) 250 mm
0225825 0.5 m extension (pair) 500 mm
0225830 1.0 m extension (pair) 1000 mm
0225835 2.0 m extension (pair) 2000 mm
0225840 45º bend (pair) N/A
0225845 90º bend (pair) N/A
0225850 Twin bracket (5) N/A
0225855 Single bracket (5) N/A
MOUNTING THE BOILER
The fixing holes for the wall-mounting bracket
should now be drilled and plugged, an
appropriate 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.
4.5.3.1 INSTALLATION OF TWIN ADAPTOR KIT (fig. 10 &
10A)
●Insertthe exhaustconnection manifold(B) onto
the appliance flue outlet and secure to the flue
spigot using the screws provided.
●Insert the silicone seal into the exhaust outlet.
●Remove the blanking plates (located to the left
of the appliance flue outlet) and – using the
same screws – install the air baffle (A).
Fig. 10
Fig. 10A
Condensate drain kit
restrictor ring
restrictor ring
flue outlet
flue outlet
air inlet
air inlet
Compact 24
Compact 28
Fig. 10B

13
Compact
4.5.3.3 HORIZONTAL TERMINATION (fig. 11)
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 130 mm hole is required for the passage of
the concentric terminal through the wall.
Dependingon siteconditionsit maybe preferable
to install the terminal assembly prior to fitting the
twin flue pipes.
Mark and drill a 130 mm hole for the passage of
the horizontal flue terminal, ensuring that there is
a 1º fall back to the boiler (17 mm per 1000 mm).
Insert the terminal assembly into the flue hole.
Push-fit the twin flue pipes onto the concentric to
twinconverter boxensuring thatthe exhaust pipe
connects to the exhaust connection on the
concentric 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 allowances
havebeenmade forconnection ontothe previous
piece and onto the concentric to twin converter.
The last twin flue pipes must be pushed 50mm
onto the male sockets of the concentric to twin
converter.
NOTE
You must ensure that the entire flue system is
properly supported and connected.
Whencutting anextension tothe required length,
you should ensure that the excess is cut from
theplainend ofthe extension.Remove anyburrs,
and check that both seals are located properly.
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.
4.5.3.4 VERTICAL TERMINATION (fig. 12)
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 130 mm hole is required for the passage of
theconcentric terminal throughthe ceiling and/
or roof.
Dependingon siteconditionsit maybe preferable
to install the terminal assembly prior to fitting the
twin flue pipes.
Fit the appropriate flashing plate to the roof and
insert the vertical flue terminal through the
flashing plate from the outside, ensuring that the
collar 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
concentric 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
allowances have been made for connection
ontothe previouspiece andonto theconcentric
to twin converter.The last twin flue pipes must
be pushed 50 mm onto the male spigots of the
concentric to twin converter.
•You must ensure that the entire flue system is
properly supported and connected.
•Ensure that any horizontal sections of pipe
have a 1º fall towards the appliance (17 mm
per 1000 mm).
•The convertor box on the vertical terminal will
haveto betemporarily removed wheninserting
the terminal through the flashing.
•Thecondensatetrap mustbe primedwithwater
prior to commissioning the boiler.
convertor box
condensate trap
Fig. 11
Fig. 12
condensate trap
convertor box
4.6 CONNECTING THE GAS AND WATER
The appliance is supplied with an accessories
packthat containslarge and smallsealing wash-
ers, service valves, and pipe connections.
The service valves are of the compression type,
the pipe connections have plain copper ends.
When connecting pipework to the valves or con-
nections, tighten the compression end first, then
insert the sealing washers before tightening the
valve or connection to the appliance. It will be
necessary to hold the valve or connection with
one spanner whilst tightening with another.
4.6.1 GAS (fig. 6)
The appliance is supplied with a 15 mm service
valve, connect a 15 mm pipe to the inlet of the
valve, and tighten both nuts.
NOTE
It will be necessary to calculate the diameter of
the gas pipe to ensure the appliance has an
adequate supply of gas.

14 Compact
4.6.2 FLOW & RETURN (fig. 6)
The appliance is supplied with 22 mm service
valvesfortheheatingconnections,connect22mm
pipetotheinletofeachvalveandtightenbothnuts.
4.6.3 SAFETY VALVE (fig. 6)
Theapplianceissuppliedwitha15mmcompres-
sion coupling. Connect a 15 mm pipe to the
coupling and tighten. It may be necessary to fit a
non-return valve if the installation is subject to
mainsknock,inordertoeliminatefalseactivation
of the domestic hot water flow switch.
4.6.4 COLD WATER INLET (fig. 6)
Theapplianceissuppliedwitha15mmstopcock,
connect a 15mm service pipe to the inlet of the
service valve and tighten both nuts. It may be
necessary to fit a pressure reducing valve if the
installation is subject high-pressure fluctuations
or high pressure surges.
4.6.5 HOT WATER OUTLET (fig. 6)
The appliance is supplied with a 15 mm copper
tail, connect a 15 mm pipe and suitable coupling
to the tail and tighten. The discharge pipe must
have a continuos fall away from the boiler to
outsideandallowanywatertodrainawaythereby
eliminating the possibility of freezing. The dis-
charge pipe must terminate in a position where
any water – possibly boiling – discharges safely
without causing damage or injury, but is still
visible.
4.7 ELECTRICAL CONNECTIONS
The electrical supply must be as specified in 3.7/
3.7A. the appliance is supplied, pre-wired with a
1.0 metre length of flex, connect the wires as
follows:
●connect the Brown wire to the L (Live) terminal
of the plug or fused isolator
●connecttheBluewiretotheN(Neutral)terminal
of the plug or fused isolator
●connectthe Green/Yellow wire to theE (Earth)
terminal of the plug or isolator
●ensure the plug or fused isolator is fitted with a
3 amp fuse.
Ifthismethod ofconnectionis unsuitable,please
refer to section 8. A qualified electrician should
connect the electrical supply to the appliance.
The electrical supply must be as specified in
section 3.7/3.7A. A qualified electrician should
connect the electrical supply to the appliance. 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
EXTERNAL CONTROL OR WIRING MUST BE
SERVED FROM THE SAME ISOLATOR AS
THAT OF THE APPLIANCE. The supply cable
from the isolator to the appliance must be 3-core
flexible sized 0.75mm to BS 6500. Wiring to the
appliance must be rated for operation in contact
with surfaces up to 90 ºC.
4.7.1 CASING REMOVAL
To gain access to the appliance electrical
connections you must first remove the casing,
proceed as follows:
●Locate and remove the 3 screws that secure
the outer casing to the appliance (fig 13).
●Gentlypull oneside ofthe casingthen theother
to disengage it from the retaining clips.
●Lift the casing upward to disengage it from the
top locating hooks and then remove.
●Store the casing and screws safely until
required.Re-fit in the reverse order.
4.7.2 ELECTRICAL CONNECTION
Theappliance terminalstrip is locatedbehind the
control fascia (fig. 14).
NOTE
If it is anticipated that external controls will be
required please refer to the wiring diagrams in
section 8 for more detailed information.
Control panel screws and casing screws
Fig. 13
Fig. 14

15
Compact
4.7.3 CONNECTINGTHE MAINS (230V) INPUT (fig.
14)
The appliance comes with a factory fitted main
electrical supplycable.If it’snecessaryto change
the main electrical cable, proceed as follow.
Open the terminal strip cover. Pass the cable
throughthe cableanchorage.Connect thesupply
cable wires (earth, live, and neutral) to their
corresponding terminals on the terminal strip.
Ensurethat the EARTHwire is leftslightly longer
that the others, this will prevent strain on the
EARTH wire should the cable become taut.
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 terminal strip cover can now be re-
fitted.

16 Compact
5.1 GAS SUPPLY INSTALLATION
Inspect the entire installation including the gas
meter, test for soundness and purge.
5.2 THE HEATING SYSTEM
The appliance contains components that may
becomedamagedorrenderedinoperable byoils
and/or debris that are residual from the installa-
tion of the system, consequently it is essential
that the appliance is flushed in accordance with
the following instructions.
5.3 INITIAL FILLING OF THE SYSTEM
Ensure both flow and return service valves are
open, remove appliance casing as described in
section 4.7.1, identify the automatic air release
valve, and loosen the dust cap by turning cap
anti-clockwiseonefullturn.IMPORTANT,THERE
ARE NO MANUAL AIR RELEASE VALVES
LOCATED ON THE APPLIANCE. Ensure all
manualair release valves located on the heating
system are closed. Using the method of filling as
described in fig. 5, slowly proceed to fill the
system,as waterenters the systemthe pressure
gauge will begin to rise, once the gauge has
reached 1 bar close the filling valve and begin
venting all manual air release valves, starting at
the lowest first. It may be necessary to go back
and top-up the pressure until the entire system
has been filled. Inspect the system for water
soundness, rectifying any leaks.
5.4 INITIAL FLUSHING
Thewholeoftheheatingsystemmustbeflushed
bothcoldand hotasdetailed insection5.9. open
all radiator or heating valves and the appliance
central heating valves. Drain the boiler and sys-
tem 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 section 5.3.
5.5 FILLING THE HOT WATER SYSTEM
Close all hot water outlets, turn appliance stop-
cockon(anti-clockwise),slowlyopeneachoutlet
until all air has been expelled and clear water is
discharged. Checkpipe-worketc.forwatersound-
ness.
5.6 PRE-OPERATION CHECKS
Beforeattemptingtheinitiallightingoftheappliance,
the following checks must be carried out:
●Ensureallgas servicevalves fromthemeter to
theapplianceareopenandthesupplypipehas
been properly purged.
SECTION 5 COMMISSIONING
●Ensurethe proper electricalchecks have been
carriedout(section7.11),particularlycontinuity,
polarity and resistance to earth.
●Ensure the 3-amp fuse – supplied with the
appliance – has been fitted.
●Ensure the system has been filled, aired, and
the pressure set to 1bar.
●Ensure the flue has been fitted properly and in
accordance with the instructions.
●Ensure all appliance service valves are open.
5.7 INITIAL LIGHTING
Ensure the electrical supply to the appliance is
switchedon.Switchthetimeclockorprogrammer
toan‘on’positionandensureallexternalcontrols
are also calling for heat.
Theappliancewillnowoperateinasdescribedin
section 1.2. Should the appliance fail to ignite,
refertosection5.6and/orsection7(faultfinding).
5.8 CHECKING BURNER PRESSURES
Althoughburner pressures are set at the factory,
it is necessary to check them during the
commissioningprocedure. Isolatethe appliance
fromthe electrical supply and remove the casing
as described in section 4.7.1.
After attaching a manometer to the outlet test
pointofthegasvalve(fig.23),restoretheelectrical
supply to the appliance, turn the selector to hot
water only (summer position), and rotate the
DHW temperature selector to maximum.
Maximum burner pressure
Fullyopenahotwateroutlet–preferablythebath
tap – and check that reading on the manometer
corresponds to the data given in section 2.3.
Minimum burner pressure
After checking the maximum burner pressure,
remove one of the black wires from the
modulating coil on the gas valve. The burner
pressurewill drop to theminimum setting. Check
that the reading on the manometer corresponds
with the data given in section 2.3.
Once the gas pressures have been checked:
● isolate the appliance from the electrical supply
● close the hot water outlet
● remove the manometer from the outlet test
point and tighten the test point screw
● refit the appliance casing.
Should either the maximum or minimum burner
pressure require to be adjusted, refer to section
7.6 for the correct adjustment procedure.
Fig. 15
Gas pressure adjustment
protective cover
Maximum pressure
adjustment screw(a) Minimum pressure ad-
justment screw (b)

17
Compact
5.9 FINALFLUSHINGOFTHEHEATINGSYSTEM
The system shall be flushed in accordance with
BS 7593. If a cleanser is to be used, it shall be
from a reputable manufacturer* and shall be
administered in strict accordance with the
manufacturers instructions.
*BothSentinel andFernox manufactureproducts
that have proved suitable for use with Vokera
appliances. Vokera Ltd.cannot comment on the
suitability of any other such product with our
appliances.
5.9.1 INHIBITORS
See section 3 “General requirements”.
5.10 SETTING THE FLOW TEMPERATURE
The heating flow temperature selector can be
adjustedfromaminimumof40°C,toamaximum
of 82 °C. In addition, when the selector is rotated
to the Auto position, the appliance will
automatically adjust the outlet flow temperature
to compensate for inclement weather
*When the selector is left within this range, the appliance will
automatically raise the outlet temperature during cold or
inclement weather conditions
5.11 SETTING THE SYSTEM DESIGN PRESSURE
The design pressure should be I minimum of 1
bar and a maximum of 1.5 bar.
The actual reading should ideally be 1 bar plus
the equivalent height in metres to the highest
point in the system above the base of the appli-
ance. (Up to the maximum of 1.5 bar total).
N.B. The safety valve is set to lift at 3 bar/ 30m/
45psig.
To lower the system pressure to the required
value,pullleveronheadofsafetyvalvetorelease
water until the required figure registers on the
pressure gauge (fig.1).
5.12 REGULATINGTHECENTRAL HEATING SYS-
TEM
Fully open all radiator and circuit valves and run
the appliance in the central heating mode until
heatedwateriscirculating.Ifconditionsarewarm
remove any thermostatic valve heads. Adjust
radiator return valves and any branch circuit
return valves until the individual return
temperatures are correct and are approximately
equal.
5.13 REGULATING THE DOMESTIC HOT WATER
The appliance is supplied with a built-in flow
restrictor that limits the amount of water passing
through the heat exchanger, thereby ensuring a
reasonable temperature at the outlet.
The outlet temperature can also be adjusted via
the DHW temperature selector.
If the required outlet temperature cannot be
obtained by rotating the DHW temperature
selector to its maximum setting, the adjustable
stopcock should be used to limit the available
flow rate at the outlet. Slowly turn the adjustable
stopcock clockwise until a satisfactory
temperature is obtained.
Please note that it’s prudent to set the domestic
hot water outlet temperature at the lowest
acceptabletemperature,ashighertemperatures
can be realised by reducing the flow rate at the
individual hot water outlets.
NOTE
Theappliancewilllighttoprovidehotwaterwhen
the domestic hot water flow switch senses a flow
rate of 2.0 litres –per minute – or more.
5.14 FINAL CHECKS
●ENSURE ALL TEST NIPPLES ON THE
APPLIANCE GAS VALVE ARE TIGHT AND
HAVE BEEN CHECKED FOR SOUNDNESS.
●ENSURETHEAPPLIANCEFLUESYSTEMIS
FITTED CORRECTLY AND IS PROPERLY
SECURED.
●ENSURE ALL PIPE WORK IS RE-CHECKED
FOR SOUNDNESS.
●RE-FIT APPLIANCE CASING.
●COMPLETE APPLIANCE LOGBOOK.
Completedetailsoftheboiler,controls,installation,
and commissioning in the logbook supplied with
the boiler. This is an important document, which
must be correctly completed and handed to the
user. Failure to install and commission the
appliance to the manufacturers instructions may
invalidate the warranty.
5.15 INSTRUCTING THE USER
Hand over all documentation supplied with this
appliance – including these instructions – and
explain the importance of keeping them in a 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
Showthe userthe positionof thefilling valveand
howtotop-upthesystempressurecorrectly,and
showthelocationofallmanualairreleasepoints.
Explain to the user how to turn off the appliance
forbothlongandshortperiods,andadviseonthe
necessary precautions to prevent frost damage.
Explain to the user that for continued safe and
efficientoperation,theappliancemustbeserviced
annually by a competent person.
Sector Range
Low sector
Auto sector
High sector
40°- 50°C
55°- 65°C*
65°- 82°C
Flow temperature selection

18 Compact
SECTION 6 SERVICING INSTRUCTIONS
6.1 GENERAL
To ensure the continued safe and efficient
operation of the appliance, it is recommended
thatitischeckedandservicedatregularintervals.
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
bycompetentpersonsuchasaVokeraengineer,
an approved service agent, British Gas, or other
CORGI registered personnel.
The following instructions apply to the appliance
and its controls, but it should be remembered
that the central heating system will also require
attention from time to time.
Always use genuine Vokera spare parts
6.2 ROUTINE ANNUAL SERVICING
Check the operation of the appliance in both ‘hot
water only’ and ‘heating and hot water’ modes.
Ensure the appliance functions as described in
section7.Comparetheperformanceoftheappli-
ance with its design specification. The cause of
any noticeable deterioration should be identified
and rectified without 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 7.6).
Check and adjust – if necessary – the system
design pressure (see section 5.11).
Carry out an analysis of the flue gases (see
section 7.7), and visually check the condition of
the entire flue assembly. Compare the results
with the appliance design specification. Any
deterioration in performance must be identified
and rectified without delay.
Ensurebothflueventuris arecleanandfreefrom
any debris or obstruction.
Ensure both the burner and heat exchanger are
clean and free from any debris or obstruction.
Inspectall joints for signsof leakage andrepair if
necessary.
Refer to the commissioning section and/or re-
placementofpartssectionfordetailedinstruction
if required.
6.3 REPLACEMENT OF COMPONENTS
Although it is anticipated that this appliance will
giveyearsofreliable,troublefreeservice,thelife
span of components will be determined by fac-
tors such as operating conditions and usage.
Should the appliance develop a fault, the fault
finding section will assist in determining which
component is malfunctioning.
6.4 MAIN HEAT EXCHANGER (de-scaling)
Themain heat exchanger may – when operating
under certain conditions – become affected by
scaling.Evidence of thiswill be a deteriorationof
the hot water performance. The heat exchanger
can be de-scaled using a proprietary de-scalant
without having to remove it from the appliance.
However the appliance must be disconnected
from the hot and cold service pipes, the de-
scalantshould be administered with strictadher-
ence to the manufacturers instructions. Re-
connect the hot and cold services only after
thorough flushing with clean water has taken
place.
6.5 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, drain the primary
water content from the appliance via the safety
valve,anddrainoffsecondarywatercontentfrom
theapplianceviaahotwateroutlet.Ensuresome
waterabsorbentclothsareavailabletocatchany
residualwaterthatmaydripfromtheapplianceor
removed component. Undertake a complete
commissioning check as detailed in section 5,
after replacing any component. ALWAYS TEST
FOR GAS SOUNDNESS IF ANY GAS CARRY-
ING COMPONENTS HAVE BEEN REMOVED
OR DISTURBED.
6.6 PUMP HEAD fig. 16
Carry out component removal procedure as de-
scribed in section 6.5.
Using a 4 mm Allen key or ‘T’ bar, unscrew and
remove the four Allen screws that hold the pump
inposition,pullfirmlyonthepumpheadtorelease
it from the base. Disconnect the electrical leads.
Replace in the reverse order.
6.7 SAFETY VALVE fig. 16
Carry out component removal procedure as de-
scribed in 6.5.
Disconnect the outlet pipe from the safety valve,
unscrew and remove the hex bush from the
safety valve outlet, remove safety valve locking
pin from appliance manifold. Replace in the
reverse order
Fig. 16
Pump
Safety valve