VOKERA Mynute 12e Release note

Installation
& Servicing
Instructions
THESE INSTRUCTIONS
TO BE RETAINED
BY USER
Mynute
12e - 16e - 20e

Contents
Design principles and operating sequence Page
1.1 Principle components 2
1.2 Mode of operation 2
1.3 Safety devices 2
Technical data Page
2.1 Performance 3
2.2 Gas pressure 3
2.3 Expansion vessel 3
2.4 Dimensions 3
2.5 Clearances 3
2.6 Connections 3
2.7 Electrical 3
2.8 Flue details 3
2.9 Efficiency 3
2.10 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 6
3.10 Timber framed building 6
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 7
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 Maximum flue lenghts 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
4.5.3.1 Installation of twin adaptor kit 12
4.5.3.2 Installation of condensate drain kit 12
4.5.3.3 Horizontal termination 12
4.5.3.4 Vertical termination 12
4.6 Connecting the gas and water 14
4.6.1 Gas 14
4.6.2 Flow and return 14
4.6.3 Safety valve 14
4.7 Electrical connections 14
4.7.1 Casing removal 14
4.7.2 Appliance terminal block 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 Pre-operation checks 16
5.6 Initial lighting 16
5.7 Checking burner pressures 16
5.8 Final flushing of the heating system 16
5.9 Setting the boiler operating temperature 16
5.10 Setting the system design pressure 16
5.11 Regulating the central heating system 17
5.12 Final checks 17
5.13 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 Component removal procedure 18
6.5 Pump head 18
6.6 Safety valve 18
6.7 Automatic air release valve 18
6.8 Water pressure switch 19
6.9 Pressure gauge 19
6.10 NTC thermistors 19
6.11 High limit thermostat 19
6.12 PCB 19
6.13 Gas valve 19
6.14 Integral time switch 19
6.15 Burner, injectors and spark electrode 20
6.16 Flue fan 20
6.17 Heat exchanger 20
6.18 Air pressure switch 21
6.19 Expansion vessel 21
6.19.1 Expansion vessel (removal) 21
Checks, adjustments and fault finding page
7.1 Checking appliance operation 22
7.2 Appliance mode of operation 22
7.3 Checking burner pressure 22
7.4 Combustion analysis test 22
7.5 Checking the expansion vessel 22
7.6 External faults 23
7.6.1 Installation faults 23
7.7 Electrical checks 23
7.7.1 Earth continuity test 23
7.7.2 Short circuit check 23
7.7.3 Polarity check 23
7.7.4 Reversed polarity or supply fault 23
7.7.5 Resistance to earth check 23
Wiring diagrams Page
8.1 ‘Y’plan using an external programmer 26
8.2 ‘S’plan using an external programmer 26
8.3 ‘Y’plan with Vokera twin channel programmer 27
8.4 ‘S’plan with Vokera twin channel programmer 27
8.5 Installation of Vokera time clock 28
8.6 Installation of Vokera twin channel programmer 28
Functional diagram 29-30
Exploded diagrams Page
Table 1 31
Table 2 32
Table 3 33
Table 4 34
Table 5 35
L.P.G. instructions Page
10.1 Technical data 36
10.2 Related documents 36
10.3 Gas supply 36
10.4 Gas supply installation 36
10.5 Burner pressures 36

1
Mynute
INTRODUCTION
TheVokera12,16,and20eMynutesarecentralheating
boilers, which – by design – incorporate electronic
ignition,circulatingpump,expansionvessel, safetyvalve,
pressure gauge, and automatic by-pass.
They are produced as room sealed, category II2H3+
appliances, suitable for wall mounting applications only.
They are provided with a fan powered flue outlet with an
annularco-axialcombustionairintakethatcanberotated
–horizontally–through360degreesforvarioushorizontal
or vertical applications.
TheMynuterangecanalso beused withthe Vokeratwin
flue system.
These appliances are designed for use with sealed
systemsonly;consequentlytheyarenotintendedforuse
on open vented systems.
The provision of stored hot water is possible by the
addition of an indirect cylinder.
A range rating facility is incorporated in the appliance.
Fig. 1
Fig.1 General Layout
1 Flue outlet
2 Air intake
3 Pressure differential switch
4 Silicone tubes (pressure diff. switch)
5 Heat exchanger
6 NTC thermistor
7 High limit thermostat
8 Spark/sensing electrode
9 Gas valve
10 Clock aperture
11 Pressure gauge
12 Thermostat
13 Mode switch
14 Warning led
15 Water pressure switch
16 Safety valve
17 Pump
18 Automatic air vent
19 Burner
20 Expansion vessel
21 Combustion chamber
22 Fan
23 Air chamber
24 Flue gas analysis test point
1
8
9
10
11
2
3
4
5
6
7
12
13
15
14
16
17
18
19
20
21
22
23
24

2
Mynute
SECTION 1: DESIGN PRINCIPLES AND OPERATING SEQUENCE
Fig. 2
1.1 PRINCIPLE COMPONENTS
●A fully integrated electronic control board
featuring mode switch, temperature control,
electronic ignition and flame supervision, anti-
cycle control, pump over-run, and appliance
fault indicator.
●Low water content copper heat exchanger.
●Integral pump
●Fan
●Expansion vessel
●Differential air pressure switch
●Water pressure switch
●Two-stage gas valve
●Pressure gauge
●Safetyvalve
1.2 MODE OF OPERATION
Whenthere is a request forheatand/orhot water
via the programmer/time clock and/or any
external control, the pump and fan are started,
thefanprovesthe differential 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
electronic circuitry allows full gas rate through
theappliance.
When the appliance reaches the desired
temperature the burner will shut down and the
boilerwill performathree-minute anti-cycle(timer
delay).
When the request for heat and/or hot water has
been satisfied the appliance pump will continue
tocirculate for aperiod of 30secondsto dissipate
any residual heat within the appliance.
1.3 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
pressure drop below the rated tolerance.
●a high limit thermostat that over-rides the
temperature control circuit to prevent or
interrupt the operation of the burner.
●a differential air pressure switch that checks
the operation of the fan and flue thereby
allowing safe operation of the burner.
●asafetyvalvewhich releases excess pressure
from the primary circuit.
return flow
gas
16
17
18
20
56
7
15

3
Mynute
SECTION 2: TECHNICAL DATA
2.1 PERFORMANCE 12e 16e 20e
Heat input 13.0 kW 17.7 kW 21.8 kW
Heat output (max) 12.0 kW 16.0 kW 19.8 kW
Heat output (min) 7.4 kW 12.0 kW 14.0 kW
Minimum working pressure 0.5 bar 0.5 bar 0.5 bar
Maximum working pressure 3.0 bar 3.0 bar 3.0 bar
Minimum flow rate 350 l/hour 350 l/hour 350 l/hour
2.2 GAS PRESSURE 12e 16e 20e
Inlet pressure (G20) 20 mbar 20 mbar 20 mbar
Maximum burner pressure 8.8 mbar 8.4 mbar 12.3 mbar
Gas rate 1.38 m3/h 1.87 m3/h 2.31 m3/h
Injector size 7x1.30 mm 9x1.35 mm 9x1.35 mm
2.3 EXPANSION VESSEL 12e 16e 20e
Capacity 6.0 litres 6.0 litres 6.0 litres
Maximum system volume 63 litres 63 litres 63 litres
Pre-charge pressure 1.0 bar 1.0 bar 1.0 bar
2.4 DIMENSIONS (all models)
Height 740 mm
Width 366 mm
Depth 315 mm
Weight 30 kg
2.5 CLEARANCES (all models)
Top 150 mm from casing or 25mm above flue elbow (whichever is applicable)
Bottom 150 mm
Sides 12 mm
Front 600 mm
2.6 CONNECTIONS (all models)
Flow & return 22 mm compression
Gas 15 mm compression
Safety valve 1/2in. BSP
2.7 ELECTRICAL (all models)
Voltage 230V/50hz
Power consumption 125 W
Internal fuse 2 AL
External fuse 3 A
2.8 FLUE DETAILS 12e 16e & 20e
Maximum horizontal flue length (concentric) 4.5 metres 3.4 metres
Maximum vertical flue length (concentric) 5.5 metres 4.4 metres
Maximum twin flue length (horizontal or vertical) 14m/14m + terminal 14m/14m + terminal
2.9 EFFICIENCY 12e 16e 20e
SEDBUK rating 79.15% 79.62% 78.05 %
Appliance type C12 - C22 - C32
Category IP20

4
Mynute
SECTION 2: TECHNICAL DATA
2.10 PUMP DUTY
Fig.3showstheflow-rateavailable–afterallowingfor pressure loss through the appliance – against system
pressure loss. When using this graph apply only the pressure loss of the system. The graph is based on a
20ºC temperature differential.
Fig. 3
Water pressure (mbar)
Litres Per Hour (x100)
0
100
200
300
400
500
600
12345 678910111213
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
Fig. 4

5
Mynute
SECTION 3: GENERAL REQUIREMENTS (UK)
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.
Itshouldbeinaccordancealsowithanyrelevant
requirements of the local authority and the
relevantrecommendations ofthefollowing 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,andinScotland,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
installationsare given in BS6798.This appliance
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.
Ifthe gassupplyserves morethanone appliance,
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 (see fig. 4).
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 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.
Referto BS 5440 Part1,whenthe terminal 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,
consequentlyitdoes 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 aregivenin BS5449
Part 1 and BS 6798. The following notes are for
general guidance only.
BS 5440 PART 1 FLUES
BS 5440 PART 2 FLUES AND 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 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

6
Mynute
SECTION 3: GENERAL REQUIREMENTS (UK)
auto air vent
3.6.1 PIPEWORK
ItisrecommendedthatcoppertubingtoBS2871
Part1isusedinconjunctionwithsolderedcapillary
joints. Where possible pipes should have a
gradient to ensure air is carried naturally to air
release points and that water flows naturally to
draincocks. Exceptwhereproviding usefulheat,
pipes should be insulated to avoid heat loss and
in particular to avoid the possibility of freezing.
Particularattentionshouldbepaidtopipespassing
throughventilatedareassuchasunderfloors,loft
space, and void areas.
3.6.2 AUTOMATIC BY-PASS
The appliance has a built-in automatic by-pass,
consequentlythereisnorequirementforanexternal
by-pass,howeverthedesignofthesystemshould
be such that it prevents boiler § ‘cycling’.
3.6.3 DRAIN COCKS
Thesemustbe 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 where airislikely to betrapped.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
6.0 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 6.19).
3.6.6 FILLING POINT
Amethodforinitialfillingofthesystemandreplacing
water lost during servicing etc. must be provided.
Thismethodoffillingmustcomply with the current
Water Supply (Water Fittings) Regulations 1999
andWaterBylaws2000(Scotland).Fig.5showsa
widely accepted method.
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
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 3mm. 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
andbesuitable forusewithacombinationboiler.
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 BUILDINGS
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’.
Fig. 5
heating return (at boiler)
stop-cock non-return valve
1 metre minimum to
the highest point of
the system, and 5
metres minimum to
the appliance
make-up vessel or tank
Fig. 5a

7
Mynute
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.
Fig. 6
return flow gas
SECTION 3: GENERAL REQUIREMENTS (UK)
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.
Itshouldbe in accordance also with anyrelevant
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 terminalis 0.5metres
(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

8
Mynute
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
These must 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 where air is likelytobetrapped. 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 6
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. 5a).
The cold feed from the make-up vessel or tank
must be fitted with an approved non-return valve
and stopcock for isolation purposes. The feed
pipe should be connected to the return pipe as
close to the boiler as possible.
3A.6.8 FREQUENT FILLING
Frequent filling or venting of the system may be
indicative of a leak. Care should be taken during
the installation of the appliance to ensure all
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
andbesuitable forusewithacombinationboiler.
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.
SECTION 3A: GENERAL REQUIREMENTS (EIRE)

9
Mynute
SECTION 4: INSTALLATION
4.4.1 IMPORTANT
Thereare twoholes onthe template. The lower
hole should be used with the telescopic flue
kit(partno.0225705&0225710).The upper hole
is for use with all other horizontal flue kits.
4.4.2 MAXIMUM FLUE LENGTHS
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 4.5.2)
(For twin flue applications, see 4.5.3)
The appliance flue outlet elbow can be rotated
through 360º on its vertical axis. In addition the
fluemaybeextendedfromtheoutletelbowinthe
horizontalplane(see4.4.2),howeveriftheflueis
to be extended or additional bends are to be
fitted, the standard horizontal flue kit (part no.
2359029) must be used. A reduction must also
bemadetothemaximumlength(seetable)when
additional bends are used.
Bend Reduction in maximum flue
length for each bend
45º bend 0.5 Metre
90º bend 1.0 Metre
Usingthe templateprovided(see 4.4.1),markand
drilla 125mmholefor thepassageof the fluepipe.
The hole should have a 1º drop from the boiler to
outside, to eliminate the possibility of rainwater
entering the 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.
4.1 DELIVERY
The appliance is delivered in a heavy-duty
cardboardcarton. Lay the carton onthefloorwith
the writing the correct way up.
4.2 CONTENTS
Contained within the carton is:
•the boiler
•the wall mounting bracket
•template
•an accessories pack containing the appliance
service valves and washers
•the instruction pack containing the installation
& servicing instructions, user instructions,
Benchmark logbook, guarantee registration
card, a 3-amp fuse and flue restrictor ring.
4.3 UNPACKING
At the top of the carton pull both sides open – do
not use a knife – unfold the rest of the carton
from around the appliance, carefully remove all
protectivepackagingfromtheappliance,and lay
the accessories etc. to one side.
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 (see fig. 7)
and flue-hole (if applicable).
Horizontal flue terminals and accessories
Part No. Description Min-Max Length
0225705 Standard telescopic flue 380mm – 600mm
(Dimension ‘X’)
0225710 Extended telescopic flue 600mm – 920mm
(Dimension ‘X’)
2359029 Horizontal flue kit
For use with add. Bends 833mm
& extensions (dimension ‘X’)
2359069 750mm extension 750mm
2359079 1500mm extension 1500mm
2359049 45º bend (pair) N/A
2359059 90º bend N/A
0225760 Wall bracket (5) N/A
type 1 = centre of rear flue hole
using only 0225705 or
0225710 flue
type 2 = centre of rear flue hole
for all other flues
1= centre of rear flue hole using ONLY 0225705 or 0225710 flue
2= centre of rear flue hole for ALL OTHER FLUES
Hole for
Room Sealed
appliance
(Rear Exit Flue)
Flue system Mynute 12e Mynute 16e/20e
Concentric Horizontal 4.25m 3.4m
Concentric Vertical 5.25m 4.4m
Twin flue 14m/14m + terminal 14m/14m + terminal
Fig. 7

10
Mynute
SECTION 4: INSTALLATION
FITTINGTHE TELESCOPIC FLUE KIT (0225705
& 0225710)
Carefullymeasurethedistancefromthecentreof
the appliance flue outlet to the face of the outside
wall (dimension ‘X’ see fig. 8). Add 50mm to
dimension ‘X’ to give the overall flue length
(dimension ‘Y’). Using the complete telescopic
flue assembly adjust the length to suit 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.
Slide the flue assembly into the previously drilled
flueholeandlocatethefluebendovertheappliance
flue outlet. Push the flue bend down over the
appliance flue outlet and ensure the correct seal
is made. Pull the flue assembly towards and over
the flue bend – using a twisting action – ensuring
the correct seal is made. Check that the terminal
protrudes past the finished outside wall by the
correct length (115mm).
NOTE
You must ensure that the entire flue system is
properly supported and connected.
Sealtheflueassemblytothewallusingcementor
asuitablealternativethatwillprovidesatisfactory
weatherproofing. The interior and exterior trim
can now be fitted.
FITTING THE STANDARD (2359029)
HORIZONTAL FLUE KIT (see 4.4.1)
Carefully measure the distance from the centre
of the appliance flue outlet to the face of the
outside wall (dimension ‘X’ see fig. 8A). Ensure
the inner (60mm) pipe is fully inserted into the
outer (100mm) pipe (when the inner pipe is fully
inserted, it stands proud of the outer pipe by
7.5mm). Add 32mm 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 865mm.
NOTE
Dimension ‘Y’ is measured from the end of the
terminal to the end of the outer (100mm) 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)into the appliance flue gas outlet
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
ensurethattheinner(60mm)pipestandsproudof
the outer (100mm) pipe by 7.5mm (see fig. 8B).
Ensure any burrs are filed or removed and that
any seals are located properly before assembly.
Connect the inner (60mm) 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 (135mm).
You must ensure that the entire flue system is
properly supported and connected.
Sealtheflueassemblytothewallusingcementor
asuitablealternativethatwillprovidesatisfactory
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–suppliedwiththeterminalkit–tothetopof
the boiler using the clips, screws, & gaskets
supplied.Theadditionalbends&extensionshave
an internal push-fit connection, care should be
takentoensurethatthecorrectsealismadewhen
assemblingthefluesystem.Connecttherequired
number of flue extensions or bends (up to the
maximumequivalentfluelength)totheflueterminal
using the clips, screws, & gaskets supplied (see
fig. 8A & 8B).
Fig. 8
115 mm
“X” + 50 mm = “Y”
Fig. 8A
Dimension “Y”
Dimension “X”
Max. 833 mm
135 mm
110
7,5
Fig. 8B
7,5 mm
Extension
Push-fit
connection
Boiler

11
Mynute
SECTION 4: INSTALLATION
NOTE
When cutting the horizontal flue terminal or an
extensionto the required length, you mustensure
that the excess is cut from the plain end of the
terminal or extension, and that the inner (60mm)
pipe is 7.5mm longer than outer (100mm) pipe
(see fig. 8A & 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.
Sealtheflueassemblytothewallusingcementor
asuitablealternativethatwillprovidesatisfactory
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(see4.4.2),however
if additional bends are fitted, a reduction must be
made to the maximum flue length (see table
below).
Reduction for bends
Usingthedimensionsgiveninfig.9asareference,
mark and cut a 105mm hole in the ceiling and/or
roof.
Fit the appropriate flashing plate to the roof and
inserttheverticalflueterminalthroughtheflashing
plate from the outside, ensuring that the collar on
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
Theverticalflueterminalis1.0metreinlengthand
cannot be cut; therefore it may be necessary to
adjust the height of the appliance to suit or use a
suitable extension.
Insert the flue restrictor ring into the appliance
flue outlet (see fig. 1), if the total flue length –
including the allowance for any additional bends
– does not exceed 1.0 metre.
Connect the vertical flue assembly to the boiler
fluespigotusingthe60mm&100mmclips,gaskets,
& screws (supplied), ensuring the correct seal is
made.Thefluesupport bracket(suppliedwiththe
vertical flue kit) can now be fitted.
Iftheverticalfluerequiresextension/soradditional
bend/s, connect the required number of flue
extensionsorbends(uptothemaximumequivalent
flue length) between the boiler and vertical flue.
NOTE
Whencuttinganextensiontotherequired length,
you must ensure that the excess is cut from the
plain end of the extension and that the inner
(60mm)pipe is 7.5mmlongerthanouter (100mm)
pipe (see 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.
Bend Reduction in maximum flue length for
each bend
45º bend 0.5 metre
90º bend 1.0 metre
Vertical flue terminal and accessories
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 750mm extension 750mm
2359079 1500mm extension 1500mm
2359049 45º bend (pair) N/A
2359059 90º bend N/A
0225760 Wall bracket (5) N/A
Fig. 9
465 mm
190 mm
300mmminimum
4.5.3 TWIN FLUE SYSTEM
TheVokera twin flue system enablesgreaterflue
distances to be achieved (see 2.8) than that of
the standard concentric flue system. It can be
used for horizontal or vertical applications,
however the twin flue system must be converted
tothe dedicatedconcentricflue kitfor termination.
It is essential that the installation of the twin flue
system be carried out in strict accordance with
these instructions.

12
Mynute
SECTION 4: INSTALLATION
GUIDANCE NOTES ON TWIN FLUE INSTALLATION
●The flue must have a fall back of 1º back to the
appliance to allow any condensate that may
form in the flue system to drain via the
condensate 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 system isadequately
supported, use at least one bracket for each
extension.
●The entire flue system must be adequately
insulatedto maintainheat withinthefluesystem
thereby reducing the possibility of condensate
production.
●As the exhaust outlet pipe can reach very high
temperatures it must be protected to prevent
persons touching the hot surface.
Bend Reduction in maximum flue length for
each bend
45º bend 1.0 metre
90º bend 1.0 metre
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 N/A
0225770 Pitched roof flashing plate N/A
0225765 Flat roof flashing plate N/A
0225815 Condensate drain kit N/A
0225820 0.25m extension (pair) 250mm
0225825 0.5m extension (pair) 500mm
0225830 1.0m extension (pair) 1000mm
0225835 2.0m extension (pair) 2000mm
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)
●Insert the restrictor ring (supplied with the
instruction pack) if the total flue length –
including the allowance for any bends – is less
than 5 metres (for 12e) and 7 metres (for 16e
& 20e).
●Insertthe exhaustconnectionmanifold ontothe
appliance flue outlet.
●Place the silicone seal (supplied with twin
adapter kit) over the rim of the exhaust
connection manifold.
●Remove the blanking plate (located to the left
of the appliance flue outlet) and – using the
same screws – install the air baffle.
4.5.3.2 INSTALLATION OF CONDENSATE DRAIN KIT
(fig. 11)
The condensate drain kit must be fitted within 1
metre of the appliance flue outlet. It is
recommended that the condensate drain kit
should be fitted in the vertical 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 3mm hole in each
and secure using the screws provided.
●Connect the air inlet pipe to the air baffle as
above.
●Thetwin flue pipesextensionsand accessories
can now be installed by pushing together (the
plain end of each extension or bend should be
pushed approximately 50mm into the female
socket of the previous piece).
The condensate drain trap must be connected
to the drain in accordance with building
Regulations or other rules in force.
Fig. 10
Condensate drain kit
Fig. 11

13
Mynute
SECTION 4: INSTALLATION
4.5.3.3 HORIZONTAL TERMINATION (See fig. 12)
The twin flue system must be converted to the
dedicated concentric flue kit for termination.
●The horizontal terminal is supplied with a built-
in converter box and cannot be shortened.
●A 130mm hole is required for the passage of
the concentric terminal through the wall.
Dependingon siteconditionsit maybepreferable
to install the terminal assembly prior to fitting the
twin flue pipes.
Mark and drill a 130mm hole for the passage of
the horizontal flue terminal, ensuring that there
isa 1º fallbackto theboiler(17mm per 1000mm).
Insert the terminal assembly into the flue hole.
Push-fitthe twin flue pipes onto the concentric to
twinconverter box ensuring thattheexhaust 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
havebeen madeforconnection ontotheprevious
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.
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.
The converter box must be removed whilst
inserting the vertical flue terminal through the
flashing plate.
4.5.3.4 VERTICAL TERMINATION (See fig. 13)
The twin flue system must be converted to the
dedicated concentric flue kit for termination.
●The vertical terminal is supplied with a built-in
converter box and cannot be shortened.
●A 130mm hole is required for the passage of
theconcentricterminal through the ceiling and/
or roof.
Dependingon siteconditionsit maybepreferable
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-fitthe 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
●Beforecuttingtwinflue pipesensure allowanceshave
been made for connection onto the previous piece
and onto the concentric to twin converter. The last
twin flue pipes must be pushed 50mm 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 (17mm per 1000mm).
Fig. 12
Twin flue Convertor Box
Horizontal Concentric
Terminal
Condensate Drain Kit
Fig. 13
Condensate Drain Kit
TwinFlueConvertorBox
Vertical roof outlet

14
Mynute
SECTION 4: INSTALLATION
4.6 CONNECTING THE GAS AND WATER
Theapplianceissuppliedwithanaccessoriespack
that contains sealing washers and service valves.
The service valves are of the compression type.
Whenconnecting pipe work tothevalves,tighten
the compression end first then insert the sealing
washers before tightening the valve to the
appliance.
NOTE
It will be necessary to hold the valve with one
spanner whilst tightening with another.
4.6.1 GAS (fig. 6)
The appliance is supplied with a 15mm service
valve, connect a 15mm pipe to the inlet of the
valve and tighten both nuts.
NOTE
It will be necessary to calculate the diameter of
the gas supply pipe to ensure the appliance has
an adequate supply of gas.
4.6.2 FLOW & RETURN (fig. 6)
The appliance is supplied with 22mm service
valves for the flow and return connections,
connect a 22mm pipe to the inlet of each valve
and tighten both nuts.
4.6.3 SAFETYVALVE (fig. 1)
Connect a suitable coupling and 15mm pipe to
thesafety valve outlet andtighten.The discharge
pipe must have a continuos fall away from the
appliancetooutsideand allow any water to drain
away thereby eliminating the possibility of
freezing. The discharge pipe must terminate in a
position where any water – possibly boiling –
discharges safely without causing damage or
injury, but is still visible.
4.7 ELECTRICAL CONNECTIONS
Theelectrical supply must be as specified in 3.7.
A qualified electrician should connect the
electrical supply to the appliance. If controls –
external to the appliance – are required, 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°C.
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 2 screws that secure
thecontrolsfascia to the appliance casing (see
fig 14);
●gently lower the control fascia until it rests;
●gentlypullone side of the casingthentheother
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 APPLIANCE TERMINAL BLOCK
The appliance terminal block is located on the
left side of the control fascia (see fig. 14a). Lo-
cate and remove the screws securing the termi-
nal block cover.
NOTE
The appliance comes with a factory fitted link to
allow basic operation of the boiler via the mode
selector switch. If it is anticipated that external
controlswillbe required please refer to thewiring
diagrams in section 8 for more detailed
information.
Fig. 14
Fig. 14a
casing screws
terminal block
cover

15
Mynute
SECTION 4: INSTALLATION
Fig. 17
Fig. 15
Fig. 17a
Outlet test nipple
Protective cap
compensator tube
Inlet test nipple
view beneath boiler
cable entry
Fig. 16
Do not remove the link wire (1 - 2) unless addi-
tional external controls are to be fitted (see sec-
tion 8). Re-fit the appliance terminal block cover.
The securing screw on the cable anchorage
should now be tightened. This must be done
before the control fascia is re-fitted in the upright
position. The appliance casing and screws can
now be re-fitted.
EN246
L135
12e
16e
Natural gas
Output (kW)
Burner pressure (mbar)
20e
0
2
4
6
8
10
12
14
7 8 9 101112 1314151617181920
4.7.3 CONNECTING THE MAINS (230V) INPUT (see
fig. 16)
Remove the terminal block cover as described
in 4.7.2. Pass the cable through the cable an-
chorage (see fig. 15).
On the terminal block there are 9 terminals from
left to right they are:
●EARTH
●LIVE
●NEUTRAL
●1
●2
●3
●4
●5
●6
Connect the supply cable wires (earth, live, and
neutral) to their corresponding terminals on the
applianceterminal block. Ensure thattheEARTH
wire is left slightly longer that the others, this will
prevent strain on the earth wire should the cable
become taut.

16
Mynute
SECTION 5: COMMISSIONING
5.1 GAS SUPPLY INSTALLATION
Inspect the entire installation including the gas
meter,testfor soundness and purge. Refer toBS
6891 for specific instruction.
5.2 THE HEATING SYSTEM
The appliance contains components that may
becomedamagedor rendered inoperable by oils
and/or debris that are residual from the
installation of the system, consequently it is
essential that the system be 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
4.7.1,identify the automatic air releasevalveand
loosen the dust cap by turning the cap anti-
clockwise one full turn. IMPORTANT, THERE
ARE NO MANUAL AIR RELEASE VALVES
LOCATED ON THE APPLIANCE. Ensure all
manualairrelease 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 water enters the system thepressure
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
Thewholeof the heating system mustbeflushed
both cold and hot as detailed in 5.8. Open all
radiatororheating valves and the appliance flow
& return service valves. Drain the boiler and
system from the lowest points. Open the drain
valve full bore to remove any installation debris
from the boiler prior to lighting. Refill the boiler
and heating system as described in 5.3.
5.5 PRE-OPERATION CHECKS
Before attempting the initial lighting of the
appliance, the following checks must be carried
out:
●ensureallgas service valves from the meter to
theappliance are openandthe supply pipe has
been properly purged;
●ensure the proper electrical checks have been
carried out, (see 7.7) particularly continuity,
polarity, and resistance to earth;
●ensure the 3 amp fuse – supplied with the
appliance – has been fitted;
●ensurethesystemhasbeen filled, vented, and
the pressure set to 1 bar;
●ensuretheflue system has been fitted properly
and in accordance with the instructions;
●ensure all appliance service valves are open.
5.6 INITIAL LIGHTING
Ensure the electrical supply to the appliance is
switchedon. Switchthe timeclockor programmer
toan ‘on’positionand ensure allexternalcontrols
are also calling for heat. Turn the mode selector
switch to the ‘on’position (fig. 1).
The appliance will now go through an ignition
sequence as described in 1.2. Should the
appliancefailtoignite,referto5.5and/orsection
7 (fault finding).
5.7 CHECKING THE BURNER PRESSURE
Although the burner pressure is factory set, it is
necessary to check it during commissioning.
Isolate the appliance from the electrical supply
andattach a suitable manometertothe gas valve
outlet test nipple (see fig. 17). Light the boiler as
describedin 5.6 and compare the reading on the
manometer with the value described in 2.2. If
adjustment is required, follow the detailed
instructions in section 7 (7.3).
Once the burner pressure has been checked,
isolate the appliance from the electrical supply,
removethe manometer,and tightenthegas valve
outlet test nipple.
5.8 FINAL FLUSHING OF THE HEATING SYSTEM
Thesystem should beflushedin accordance with
BS 7593. Turn on the boiler for central heating
and hot water and allow the boiler to reach
temperature. Turn off the boiler and drain the
system whilst still hot.
Refill the boiler and system as described in 5.3.
Although not necessary for the correct operation
of the boiler, an inhibitor may be added at this
point. Contact the inhibitor manufacturer for
further information regarding application and
dosage.
5.9 SETTING THE BOILER OPERATING
TEMPERATURE
The flow outlet temperature can be adjusted
between 40°C - 80°C via the thermostat knob
(see fig.1).
5.10 SETTING THE SYSTEM DESIGN PRESSURE
The design pressure should be a minimum of 1
bar and a maximum of 1.5 bar.
The actual reading should ideally be 1bar plus
theequivalent heightin metres(0.1bar =1metre)
tothehighest point in the system above the base
of the appliance (up to the maximum of 1.5 bar
total).
N.B. The safety valve is set to lift at 3 bar/30
metres/45 psig.
To lower the system pressure to the required
value,pull leveronhead ofsafety valve torelease
water until the required figure registers on the
pressure gauge (see fig. 1).

17
Mynute
SECTION 5: COMMISSIONING
5.11 REGULATING THE CENTRAL HEATING
SYSTEM
Fully open all radiator and circuit valves and run
theapplianceforboth heating and hot water until
heatedwater is circulating.Ifconditions arewarm
remove any thermostatic heads. Adjust radiator
returnvalves and any branchcircuitreturn valves
untilthe individualreturn temperaturesarecorrect
and are approximately equal.
5.12 FINAL CHECKS
●ENSURE ALL TEST NIPPLES ON THE
APPLIANCE GAS VALVE HAVE BEEN
TIGHTENED AND CHECKED FOR
SOUNDNESS.
●ENSURETHEAPPLIANCEFLUESYSTEM IS
FITTED CORRECTLY AND IS PROPERLY
SECURED.
●ENSURE ALL PIPE WORK IS RE-CHECKED
FOR SOUNDNESS.
●RE-FIT APPLIANCE CASING.
●COMPLETE APPLIANCE LOGBOOK.
Complete details of the boiler, 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.
5.13 INSTRUCTING THE USER
Hand over all documentation supplied with this
appliance – including these instructions – and
explainthe 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
its associated controls correctly.
Showtheuserthelocation of the filling valve and
howtotop-upthe system pressure correctly, and
showthe location of allmanualair release points.
Explain to the user how to turn off the appliance
for both long and short periods and advise on
the necessary precautions to prevent frost
damage.
Explain to the user that for continued safe and
efficient operation, the appliance must be
serviced annually by a competent person.

18
Mynute
SECTION 6: SERVICING
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
anditscontrols,butitshouldberememberedthat
the central heating and the domestic hot water
systems will also require attention from time to
time.
6.2 ROUTINE ANNUAL SERVICING
Checktheoperationoftheapplianceandensure
it functions as described in section 7. Compare
the performance of the appliance with its design
specification. The cause of any noticeable
deterioration should be identified and rectified
without delay.
Thoroughly inspect the appliance for signs of
damageordeteriorationespeciallythefluesystem
and the electrical apparatus.
Check and adjust – if necessary – all burner
pressure settings. (See 7.3)
Check and adjust – if necessary – the system
design pressure. (See 5.10)
Carry out an analysis of the flue gases (see 7.4),
andvisually check the condition of the entire flue
assembly. Comparetheresultswiththeappliance
design specification. Any deterioration in
performance must be identified and rectified
without delay.
Ensurebothflue venturisare cleanandfreefrom
any debris or obstruction.
Ensure both the burner and heat exchanger are
clean and free from any debris or obstruction.
Inspectalljointsfor signs of leakage and repair if
necessary.
Refer to the commissioning section and/or
replacement of parts section for detailed
instruction if required.
6.3 REPLACEMENT OF COMPONENTS
Although it is anticipated that this appliance will
giveyearsofreliable,troublefreeservice,thelife
spanofcomponentswillbedeterminedbyfactors
such as operating conditions and usage. Should
the appliance develop a fault, the fault finding
sectionwillassistindeterminingwhichcomponent
is malfunctioning.
6.4 COMPONENT REMOVAL PROCEDURE
Toremoveacomponent,accesstotheinteriorof
the appliance is essential. Isolate the appliance
from the electrical supply and remove the fuse.
Andwhennecessary, close all service valves on
the appliance, remove the appliance casing as
describedinsection4.7.1,drainthewatercontent
from the appliance via the safety valve. Ensure
some water absorbent cloths are available to
catch any residual water that may drip from the
appliance or removed component. Undertake a
complete commissioning check as detailed in
section 5, after replacing any component.
ALWAYS TEST FOR GAS SOUNDNESS IF
ANY GAS CARRYING COMPONENTS HAVE
BEEN REMOVED OR DISTURBED.
6.5 PUMP HEAD (see fig. 18)
Carry out component removal procedure as
described in 6.4.
Using a 4mm Allen key or ‘T’ bar, unscrew and
removethe four Allen screws that hold the pump
in position, pull firmly on the pump head to
releaseitfromthebase.Disconnecttheelectrical
leads. Replace in the reverse order.
6.6 SAFETY VALVE (see fig. 18)
Carry out component removal procedure as
described in 6.4.
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
6.7 AUTOMATIC AIR RELEASE VALVE (see fig.
18) (AAV)
Carry out component removal procedure as
described in 6.4.
Remove the locking pins from both the pressure
gauge and expansion pipe connections from the
pump base. Remove both the pressure gauge
phial and expansion pipe from the pump base.
Usinga suitablepairof pumppliers, unscrewthe
AAVfromthepumpbase.Replaceinthereverse
order.
fig. 18
Pump
Safety valve