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)