VOKERA Mynute 12HE, Mynute 15HE, Mynute 35HE, Mynute 20HE, Mynute 25HE Installation And Servicing Instructions

Supplied By www.heating spares.co Tel. [phone]

Installation
& Servicing
Instructions

0694

0694BR1207

THESE INSTRUCTIONS
TO BE RETAINED
BY USER

Supplied By www.heating spares.co Tel. [phone]

Contents

Design principles & operating sequence Page

1.1 Principle components 3

1.2 Mode of operation (at rest) 3

1.3 Mode of operation 3

1.4 Safety devices 3

Technical data Page

2.1 Central heating 4

2.2 Gas pressures 4

2.3 Expansion vessel 4

2.4 Dimensions 4

2.5 Clearances 4

2.6 Connections 4

2.7 Electrical 4

2.8 Flue details (concentric) 4

2.8A Flue details (twin pipes) 4

2.8B Flue details (80/125) 4

2.9 Efficiency 4

2.10 Emissions 4

2.11 Pump duty 5

General requirements (UK) Page

3.1 Related documents 6

3.2 Location of appliance 6

3.3 Gas supply 6

3.4 Flue system 6

3.5 Air supply 6

3.6 Water circulation 6

3.7 Electrical supply 7

3.8 Mounting on a combustible surface 7

3.9 Timber framed buildings 7

3.10 Inhibitors 7

General requirements (EIRE) Page

3A.1 Related documents 8
3A.2 Location of appliance 8
3A.3 Gas supply 8
3A.4 Flue system 8
3A.5 Air supply 8
3A.6 Water circulation 8
3A.7 Electrical supply 9
3A.8 Mounting on a combustible surface 9
3A.9 Timber framed buildings 9
3A.10Inhibitors 9
3A.11 Declaration of conformity 9

Installation Page

4.1 Delivery 10

4.2 Contents 10

4.3 Unpacking 10

4.4 Preparation for mounting the appliance 10

4.5 Fitting the flue 10

4.6 Connecting the gas & water 14

4.7 Electrical connections 14

6.8 Water pressure switch 19

6.9 Primary thermistor 19

6.10 Return thermistor 19

6.11 Printed circuit board 19

6.12 Gas valve 19

6.13 Electrodes and condense sensor 20

6.14 Flue fan & mixer 20

6.15 Burner 20

6.16 Main heat exchanger 20

6.17 Automatic by-pass 21

6.18 Expansion vessel 21

6.19 Condense trap removal 21

6.20 Flue collector removal 22

Checks, adjustments and fault finding Page

7.1 Checking appliance operation 22

7.2 Appliance modes of operation 22

7.3 Appliance fan speed 23

7.4 Checking the CO2 & adjusting the valve 24

7.5 Combustion analysis test 24

7.6 Checking the expansion vessel 24

7.7 External faults 24

7.8 Electrical checks 24

7.9 Fault finding 25

7.10 Component values & characteristics 25

7.11 Boiler configuration 27

7.12 Final fault codes 26

Wiring diagrams Page

8.1 External wiring 27

8.2 Typical control applications 27

8.3 Other devices 27

8.4 Vokera twin-channel programmer 27

Exploded diagrams Page

9.1 Table 1 31

9.2 Table 2 32

9.3 Table 3 33

9.4 Table 4 34

9.5 Table 5 35

L.P.G. instructions Page

10.1 Related documents 36

10.2 Technical data 36

10.3 Converting the appliance gas type 36

10.4 Gas supply 36

10.5 Gas supply installation 36

10.6 Adjusting the gas valve 36

10.7 Appliance fan speed 3 7

Benchmark 38-39

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 of the system 16

5.5 Pre-operation checks 16

5.6 Initial lighting 16

5.7 Checking gas pressure & combustion analysis 16

5.8 Final flushing of the heating system 17

5.9 Setting the boiler operating temperature 17

5.10 Setting the system design pressure 17

5.11 Regulating the central heating system 17

5.12 Final checks 17

5.13 Instructing the user 17

Servicing 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 assembly 18

6.6 Safety valve 18

6.7 Lower automatic air release valves 19

Supplied By www.heating spares.co Tel. [phone]

INTRODUCTION

The Mynute HE comprises a range of high-efficiency
system boilers with outputs ranging from 12 to 35kW.
These appliances – by design – incorporate electronic
ignition, circulating pump, expansion vessel, safety val­ve, pressure gauge, and automatic by-pass.

The Mynute HE range are produced as room sealed,
category II2H3P appliances, suitable for internal wall
mounting applications only. Each appliance is provided
with a fan powered flue outlet with an annular co-axial
combustion air intake that can be rotated – horizontally –
through 360 degrees for various horizontal or vertical

Mynute

12-15-20-25 HE

Fig. 1

R

F

G

Mynute

30-35 HE

applications. The Mynute HE can also be used with the
V okera twin flue system. The Myn ute HE is approv ed f or
use with C13 & C33 type flue applications.

These appliances are designed for use with a sealed
system only; consequently they are not intended for use
on open vented systems.

This booklet is an integral part of the appliance. It is
therefore necessary to ensure that the booklet is handed
to the person responsible for the property in which the
appliance is located/installed. A replacement copy can
be obtained from Voker a customer services.

General layout (fig. 1)

1 Safety valve
2 Pressure switch
3 Pump
4 Bottom auto air vent (AAV)
5 Injector
6 Condense trap
7 Return sensor
8 Flue gas analysis test point
9 Flue outlet & air intake
10 Ignition transformer
11 Top AAV
12 Flow sensor
13 High limit thermostat
14 Limit thermostat
15 Sensing Electrode
16 Spark Electrode
17 Cylindric Burner
18 Condensate level sensor
19 Main heat exchanger
20 Top AAV pipe
21 Fan assembly
22 Mixer
23 Expansion vessel
24 Hydraulic manifold
25 Gas valve
26 Condensing drain

R

GF

R Heating return connection
F Heating flow connection
G Gas connection

1

Supplied By www.heating spares.co Tel. [phone]

HYDROMETRE

GREEN LED

2-digit LED

display

MODE SELECTOR

RED LED

SWITCH

TEMPERATURE SELECTOR

Fig. 1A

Boiler at reset/standby Select this position if/when the boiler requires to be reset
Boiler switched OFF Select this position if you w ant the boiler to remain OFF (this will over-ride any

heating/hot water request from the time-clock/programmer)

Boiler switched ON Select this position when you want the boiler to respond to a heating/hot water

request from the time-clock/programmer

°C

T emperature selector Move the temperature selector clockwise to increase the boiler outlet temperature, or

counter-clockwise to reduce the outlet flow temperature

2-digit LED display Displays the current outlet temperature of the boiler . During a fault condition, the

appropriate fault code will be display ed (refer to the users handbook for instructions

regarding fault codes)
Green LED lit Boiler is working/responding to a heating/hot water request
Red LED lit Boiler has identified a fault and has failed-saf e. Ref er to users handbook for

instructions on how to reset
Pressure gauge Ensure the system pressure is set correctly (minimum 0.5-bar)

2

Supplied By www.heating spares.co Tel. [phone]

SECTION 1 DESIGN PRINCIPLES AND OPERATING SEQUENCE

1.1 PRINCIPLE COMPONENTS

A fully integrated electronic control board featuring
electronic temperature control, anti-cycle control,
pump over-run, self-diagnostic fault indicator, full
air/gas modulation.

●●

● Radial aluminium heat exchanger.

●●

●●

● Electronic ignition with flame supervision

●●

●●

● Integral high-head pump

●●

●●

● Fan

●●

●●

● Expansion vessel

●●

●●

● Water pressure switch

●●

●●

● Condensate level sensor

●●

●●

● Pressure gauge

●●

●●

● Safety valve

●●

1.2 MODE OF OPERATION (at rest)

When the appliance is at rest and there are no
requests for heating or hot water, the following
functions are active:

●●

● 2-stage frost-protection system – the frost-

●●

protection system protects the appliance against
the risk of frost damage. The first stage enables
activation of the pump should the temperature
of the appliance fall to 6oC. Should the first stage
become active, the appliance will function on
minimum +25% power until it reaches 35oC.

●●

● Anti-block function – the anti-block function

●●

enables the pump to be energised for short
periods, when the appliance has been inactive
for more than 24-hours.

●●

● fan speed sensor to ensure safe operation of the

●●

burner;

●●

● a high limit thermostat that over-rides the tem-

●●

perature control circuit to prevent or interrupt the
operation of the burner;

●●

● flame sensor that will shut down the burner when

●●

no flame signal is detected;

●●

● a sensor that interrupts the operation of the

●●

appliance if the condense pipe becomes blocked;

●●

● a safety valve which releases excess pressure

●●

from the primary circuit.

1.3 MODE OF OPERATION

When there is a request for heat and/or hot water,
via the programmer/time clock and/or any external
control, the pump and fan are started, the fan
speed will modulate until the correct signal voltage
is received at the control PCB. At this point an
ignition sequence is enabled.
Ignition is sensed by the electronic circuitry to
ensure flame stability at the burner. Once
successful ignition has been achieved, the
electronic circuitry increases the gas rate to 75%
of the MAX Heating (set by the corresponding HTG
trimmer) for a period of 15 minutes. Thereafter,
the boiler’s output will either be increase to
maximum or modulate to suit the set requirement.
When the appliance reaches the desired
temperature the burner will shut down and the
boiler will perform a three-minute anti-cycle (timer
delay).
When the request for heat has been satisfied the
appliance pump and fan may continue to operate
to dissipate any residual heat within the appliance.

1.4 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
(when lockout condition is reached), fan and
burner should the system water pressure drop
below the rated tolerance;

Fig. 2

expansion

vessel

safety
valve

pump

return

temperature

sensor

bottom

CH

return

AAV

automatic

by-pass

CH

flow

pressure

switch

drain
valve

main heat

exchanger

3

Supplied By www.heating spares.co Tel. [phone]

SECTION 2 TECHNICAL DATA

2.1 Central Heating 12HE 15HE 20HE 25HE 30HE 35HE

Heat input (kW) 12 15 20 25 30 34.6
Maximum heat output (kW) 60/80°C 11.84 14.81 19.68 24.53 29.31 33.67
Minimum heat output (kW) 60/80°C 3.5 3.5 5 6 7 7
Maximum heat output (kW) 30/50°C 12.74 15.90 21.16 26.30 6.84 36.54
Minimum heat output (kW) 30/50°C 3.7 3.71 5.30 6.37 7.41 7.41
Minimum working pressure 0.5 bar
Maximum working pressure 2.7 bar
Minimum flow rate 350 l/h

2.2 Gas Pressures 12HE 15HE 20HE 25HE 30HE 35HE

Inlet pressure (G20) 20.0 mbar
Maximum gas rate (m3/hr) 1.27 1.59 2.12 2.64 3.17 3.66
Minimum gas rate (m3/hr) 0.37 0.37 0.53 0.63 0.74 0.74
Injector size 4.6mm 4.6mm 4.6mm 6.7mm 7.0mm 7.0mm

2.3 Expansion Vessel 12HE 15HE 20HE 25HE 30HE 35HE

Capacity 6-litres 8-litres 10-litres
Maximum system volume 63-litres 76-litres 91-litres
Pre-charge pressure 1.0 bar

2.4 Dimensions 12HE 15HE 20HE 25HE 30HE 35HE

Height 740mm 780mm 780mm
Width 400mm 400mm 450mm
Depth 340mm 358mm 358mm
Dry weight (kg)

2.5 Clearances Mynute HE Range

Sides 12mm
Top 150mm from casing or 25mm above flue elbow (whichever is applicable)
Bottom 150mm
Front 600mm

2.6 Connections Mynute HE Range

Flow & return 22mm
Gas 15mm
Safety valve 15mm
Condense 21mm

2.7 Electrical 12HE 15HE 20HE 25HE 30HE 35HE

Power consumption (Watts) 150 150 150 150 165 165
Supply (V/Hz) 230/50
Internal fuse 3.15A T (for PCB) - 3.15A F (for connections block)
External fuse 3A

2.8 Flue Details (concentric - 60/100) 12HE 15HE 20HE 25HE 30HE 35HE

Maximum horizontal flue length (60/100mm) 7.8m 7.8m 7.8m 7.8m 7.8m 7.8m
Maximum vertical flue length (60/100mm) 8.8m 8.8m 8.8m 8.8m 8.8m 8.8m

2.8A Flue Details (concentric 80/125mm) 12HE 15HE 20HE 25HE 30HE 35HE

Maximum horizontal flue length (80/125mm) 20m 20m 20m 20m 20m 20m
Maximum vertical flue length (80/125mm) 25m 25m 25m 25m 25m 25m

2.8A Flue Details (twin pipes) 12HE 15HE 20HE 25HE 30HE 35HE

Maximum horizontal flue length (80mm/80mm) 40m/40m 40m/40m 40m/40m 40m/40m 40m/40m 40m/40m
Maximum vertical flue length (80mm/80mm) 40m/40m 40m/40m 40m/40m 40m/40m 40m/40m 40m/40m

2.9 Efficiency 12HE 15HE 20HE 25HE 30HE 35HE

SEDBUK (%) 90.7 90.7 90.5 90.4 90.2 90.0

2.10 Emissions 12HE 15HE 20HE 25HE 30HE 35HE

CO2 @ maximum output (%) 9.0 9.0 9.0 9.0 9.0 9.0
CO2 @ minimum output (%) 9.0 9.0 9.0 9.0 9.0 9.0
CO/CO2 ratio @ maximum output 0.001 to 1 0.001 to 1 0.001 to 1 0.0002 to 1 0.0002 to 1 0.0002 to 1
CO/CO2 ratio @ minimum output 0.0002 to 1 0.0002 to 1 0.0004 to 1 0.0003 to 1 0.0003 to 1 0.0003 to 1
CO @ maximum output (mg/kWh) 107.5 129.0 161.3 204.3 215 268.8
CO @ minimum output (mg/kWh) 21.5 21.5 43.0 32.3 32.3 32.3
NOx @ maximum output mg/kWh) 88.3 88.3 79.4 88.3 88.3 88.3
NOx @ minimum output (mg/kWh) 35.3 35.5 53.0 61.8 70.6 70.6
NOx rating class 5 class 5 class 5 class 5 class 5 class 5

Band ‘A’ Band ‘A’ Band ‘A’ Band ‘A’ Band ‘A’ Band ‘A’

Ref. Condition 15 °C, 1013,25 mbar, dry gas
NOTE: L.P.G. data refer to section 10

4

Supplied By www.heating spares.co Tel. [phone]

2.11 PUMP DUTY

Fig. 3 shows the flow-rate available – after allow­ing for pressure loss through the appliance – for
system requirements. When using this graph,
apply only the pressure loss of the system. The
graph is based on a 20 °C temperature differential.

Mynute

12-15-20-25 HE

5,0
4,8
4,6
4,4
4,2
4,0
3,8
3,6
3,4
3,2
3,0
2,8
2,6
2,4
2,2
2,0
1,8
1,6
1,4
1,2
1,0
0,8

Residual head (x 100 mbar)

0,6
0,4
0,2
0,0

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

1st speed

2nd speed

Flow rate (l/h)

Fig. 3

Fig. 4

3rd speed

Mynute

30-35 HE

6,0
5,8
5,6
5,4
5,2
5,0
4,8
4,6
4,4
4,2
4,0
3,8
3,6
3,4
3,2
3,0
2,8
2,6
2,4
2,2
2,0
1,8
1,6
1,4
1,2
1,0
0,8

Residual head (x 100 mbar)

0,6
0,4
0,2
0,0

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

1st speed

2nd speed

Flow rate (l/h)

3rd speed

Key Location Minimum distance

A Below an opening (window, air-brick, etc.) 300 mm
B Above an opening (window, air-brick, etc.) 300 mm
C To the side of an opening (window, air-brick, etc.) 300 mm
D Below gutter, drain-pipe, etc. 25 mm
E Below eaves 25 mm

F Below balcony, car-port roof, etc. 25 mm
G To the side of a soil/drain-pipe, etc. 25 mm
H From internal/external corner or boundary 300 mm

I Above ground, roof, or balcony level 300 mm
J From a surface or boundary facing the terminal 1200 mm
K From a terminal facing a terminal 1200 mm
L From an opening in the car-port into the building 1200 mm

M Vertically from a terminal on the same wall 1500 mm
N Horizontally from a terminal on the same wall 300 mm

P From a structure to the side of the vertical terminal 500 mm

Q From the top of the vertical terminal to the roof flashing As determined by the fixed collar

of the vertical terminal

5

Supplied By www.heating spares.co Tel. [phone]

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

The installation of this boiler must be in accord­ance with the relevant requirements of the Gas
Safety (Installation & Use) Regulations, the local
building 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.

It should be in accordance also with any relevant
requirements of the local authority and the rel­evant recommendations of the following British
Standard Codes of Practice.

3.2 LOCATION OF APPLIANCE

The appliance may be installed in any room or
internal space, although particular attention is
drawn to the requirements of the current I.E.E.
wiring regulations, and in Scotland, the electrical
provisions of the Building Regulations, with re­spect to the installation of the appliance in a room
or internal space containing a bath or shower.
When an appliance is installed in a room or internal
space containing a bath or shower, the appliance
or any control pertaining to it must not be within
reach of a person using the bath or shower.

the appliance gas inlet connection must not be
used. The installation must be tested for sound­ness in accordance with BS6891.
If the gas supply serves more than one 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

The terminal should be located where the disper­sal of combustion products is not impeded and
with due regard for the damage and discoloration
that may occur to building products located nearby.
The terminal must not be located in a place where
it is likely to cause a nuisance (see fig. 4).
In cold and/or humid weather, water vapour will
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.
Refer to BS 5440 Part 1, when the terminal is 0.5
metres (or less) below plastic guttering or 1 metre
(or less) below painted eaves.

BS 5440
BS 5449
BS 6798
BS 6891
BS 7074

PART 2
PART 1

PART 1

The location chosen for the appliance must permit
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 instal­lations are given in BS 6798. This appliance is not
suitable for external installation.

3.3 GAS SUPPLY

The gas meter – as supplied by the gas supplier –
must be checked to ensure that it is of adequate
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

FLUES & VENTILATION
FORCED CIRCULATION HOT WATER SYSTEMS
INSTALLATION OF BOILERS OF RATED INPUT NOT EXCEEDING 60kW
LOW PRESSURE INSTALLATION PIPES
APPLICATION, SELECTION, AND INSTALLTION OF EXPANSION VESSELS AND ANCIL-

LARY EQUIPMENT FOR SEALED WATER SYSTEMS

3.5 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.

3.6 WATER CIRCULATION

Detailed recommendations are given in BS 5449
Part 1 and BS 6798. The following notes are for
general guidance only.

3.6.1 PIPEWORK

It is recommended that copper tubing to BS 2871
Part 1 is used in conjunction with soldered capil­lary joints.
Where possible pipes should have a gradient to
ensure air is carried naturally to air release points
and that water flows naturally to drain cocks.
Except where providing useful heat, pipes should
be insulated to avoid heat loss and in particular to
avoid the possibility of freezing. Particular atten­tion should be paid to pipes passing through

6

Supplied By www.heating spares.co Tel. [phone]

ventilated 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

These must 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

These must be positioned at the highest points in
the system where air is likely to be 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 6
litres (12-15-20HE), 8 (25HE) and 10 litres (30­35HE) 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

A method for initial filling of the system and re­placing water lost during servicing etc. is required
(see fig. 5). This method of filling must comply
with the current Water Supply (Water Fittings)
Regulations 1999 and W ater Bylaws 2000 (Scot­land).

control

valve

temporary

connection

control

valve

Make-up vessel
or tank

Automatic
air-vent

Non-return

valve

Fig. 5A

Stopcock

5.0 metres minimum

Heating
return

3.6.8 FREQUENT FILLING

Frequent filling or venting of the system may be
indicative of a leak. Care should be taken during
the installation of the appliance to ensure all
aspects of the system are capable of withstanding
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 complete
isolation from the supply. The preferred method is
by using a double-pole switch with a contact
separation of at least 3,5mm (3° high-voltage
category). The switch must only supply the appli­ance and its corresponding controls, i.e. time
clock, room thermostat, etc. Alternatively an un­switched shuttered socket with a fused 3-pin plug
both complying with BS 1363 is acceptable.

3.8 MOUNTING ON A COMBUSTIBLE SURFACE
If the appliance is to be fitted on a wall of combus­tible material, a sheet of fireproof material must
protect the wall.

3.9 TIMBER FRAMED BUILDINGS

flow/return

pipe

Fig. 5

3.6.7 LOW PRESSURE SEALED SYSTEM

double

check valve

supply

pipe

3.10 INHIBITORS

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.

If the appliance is to be fitted in a timber framed
building, it should be fitted in accordance with the
Institute of Gas Engineers publication (IGE/UP/7)
‘Guide for Gas Installations in Timber Frame
Buildings’.

V okera recommend that an inhibitor - suitab le for
use with copper and aluminium heat exchangers

- is used to protect the boiler and system from
the effects of corrosion and/or electrolytic action.
The inhibitor must be administered in strict ac­cordance with the manufacturers instructions*.

*Water treatment of the complete heating system

- including the boiler - should be carried out in
accordance with BS 7593 and the Domestic Water
Treatment Association’s (DWTA) code of prac­tice.

7

Supplied By www.heating spares.co Tel. [phone]

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

The installation of this boiler must be in accord­ance with the relevant requirements of the local
building regulations, the current ETCI National
Rules for Electrical Installations and the bylaws of
the local water undertaking.
It should be in accordance also with any relevant
requirements of the local and/or district authority .

3A.2 LOCATION OF APPLIANCE

The appliance may be installed in any room or
internal space, although particular attention is
drawn to the requirements of the current ETCI
National Rules for Electrical Installations, and I.S.
813, Annex K.
When an appliance is installed in a room or internal
space containing a bath or shower, the appliance
or any control pertaining to it must not be within
reach of a person using the bath or shower.
The location chosen for the appliance must permit
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/cupboard
may be utilised provided 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 –
must be checked to ensure that it is of adequate
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.
If the gas supply serves more than one appliance,
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

The terminal should be located where the disper­sal of combustion products is not impeded and
with due regard for the damage and discoloration
that may occur to building products located nearby.
The terminal must not be located in a place where
it is likely to cause a nuisance (see I.S. 813).

In cold and/or humid weather, water vapour will
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.
Refer to I.S. 813, when the terminal is 0.5 metres
(or less) below plastic guttering or 1 metre (or less)
below painted eaves.

3A.5 AIR SUPPLY

The following notes are intended for general guid­ance only.
This appliance is a room-sealed, fan-flued boiler,
consequently it does not require a permanent air
vent for combustion air supply.
When installed in a cupboard or compartment,
ventilation for cooling purposes is also not 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
ensure air is carried naturally to air release points
and that water flows naturally to drain cocks.
Except where providing useful heat, pipes should
be insulated to avoid heat loss and in particular to
avoid the possibility of freezing. Particular atten­tion should be paid to pipes passing through
ventilated areas such as under floors, loft space,
and void areas.

3A.6.2AUTOMATIC 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

These must be positioned at the highest points in
the system where air is likely to be 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 6
litres (12-15-20HE), 8 (25HE) and 10 litres (30­35HE) 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).

8

Supplied By www.heating spares.co Tel. [phone]

3A.6.6 FILLING POINT

A method for initial filling of the system and replacing
water lost during servicing etc. is required. You
should ensure this method of filling complies with
the local water authority regulations.

3A.6.7 LOW PRESSURE SEALED SYSTEM

An alternative method of filling the system would
be from an independent make-up vessel or tank
mounted in a position at least 1 metre above the
highest point in the system and at least 5 metres
above the boiler (see fig. 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
aspects of the system are capable of withstanding
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 complete
isolation from the supply. The preferred method is
by using a double-pole switch with a contact
separation of at least 3,5mm (3° high-voltage
category). The switch must only supply the appli­ance and its corresponding controls, i.e. time
clock, room thermostat, etc.

3A.8 MOUNTING ON A COMBUSTIBLE SURFACE

If the appliance is to be fitted on a wall of combus­tible material, a sheet of fireproof material must
protect the wall.

Mynute

12-15-20 HE

Mynute

25-30-35 HE

3A.9 TIMBER FRAMED BUILDINGS

If the appliance is to be fitted in a timber framed
building, it should be fitted in accordance with I.S.
813 and local Building Regulations.
The Institute of Gas Engineers publication (IGE/
UP/7) ‘Guide for Gas Installations in Timber Frame
Buildings’ gives specific advice on this type of
installation.

3A.10 INHIBITORS

V okera recommend that an inhibitor - suitab le for
use with aluminium heat exchangers - is used to
protect the boiler and system from the effects of
corrosion and/or electrolytic action. The inhibitor
must be administered in strict accordance with
the manufacturers instructions*.

*Water treatment of the complete heating system ­including the boiler - should be carried out in accord­ance with I.S. 813 and the Domestic Water Treat­ment Association’s (DWTA) code of practice.

3A.11 DECLARA TION 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
responsible person and also to the gas supplier if
required.

Fig. 6

9

Supplied By www.heating spares.co Tel. [phone]

SECTION 4 INSTALLATION

4.1 DELIVERY

Due to the weight of the appliance it may be
necessary for two people to lift and attach the
appliance to its mounting. The appliance is con­tained within a heavy-duty cardboard carton. Lay the
carton on the floor with the writing the correct way up.

4.2 CONTENTS

Contained within the carton is:

• the boiler

• the wall bracket

• template

• an accessories pack containing appliance serv-

ice connections and washers

• the instruction pack containing the installation &
servicing instructions, user instructions, guar­antee registration card, and a 3-amp fuse.

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 protec­tive packaging from the appliance, and lay the
accessories etc. to one side. Protective gloves
should be used to lift the appliance, the appliance
back-frame should be used for lifting points.

4.4 PREPARATION FOR MOUNTING THE APPLI­ANCE

The appliance should be mounted on a smooth,
vertical, non-combustible surface, which must be
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 – using the template supplied – carefully
mark the position of the wall- mounting bracket
(see fig. 6) and flue-hole (if applicable).

Reduction for additional bends

Bend Reduction in maximum flue length for each bend
45° bend

90° bend

Horizontal flue terminals and accessories

Part No.
520

521
522
523
524
525
526
527
528
529

0.5 metre

1.0 metre

Description
Horizontal flue kit

Telescopic flue kit
Plume management kit
90-degree bend
45-degree bends (pair)
500mm extension
1000mm extension
2000m extension
Telescopic extension
Wall bracket pack (5)

Length
900 mm

350 /530 mm
1370 mm
N/A
N/A
500mm
1000 mm
2000 mm
350 /730 mm
208mm

Using the template provided, mark and drill a
115mm hole for the passage of the flue pipe. The
hole should be drilled to ensure any condense fluid
that forms, is allowed to drain back to the appliance
(see fig. 7A).
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 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 HORIZONT AL FLUE

(For concentric vertical flue, see 4.5.2)
(For twin flue applications, see 4.5.3)
The appliance can be used with either the Vokera
condensing 60/100mm concentric flue system or
the optional 80/125mm concentric flue system.

NOTE

These instructions relate only to the Vokera
condensing 60/100mm concentric flue system.
For specific details on the installation of the 80/
125mm concentric flue system please refer to the
instructions supplied.

The appliance flue outlet elbow can be rotated
through 360º on its vertical axis. In addition the
flue may be extended from the outlet elbow in the
horizontal plane (see 2.8). A reduction must also
be made to the maximum length (see table below)
when additional bends are used.

Fig. 7

10

Supplied By www.heating spares.co Tel. [phone]

FITTING THE HORIZONT AL FLUE KIT

Carefully measure the distance from the centre of
the appliance flue outlet to the edge of the finished
outside wall (dimension X). Add 65mm to
dimension X to give you Dimension Y (see fig 7A).
Measure dimension Y from the terminal end of
the concentric flue pipe and cut off the excess
ensuring any burrs are removed. Pass the
concentric flue pipe through the previously drilled
hole. Fit the flue bend to the boiler flue outlet and
insert the concentric flue pipe into the flue bend
ensuring the correct seal is made.
Using the clamp, gasket, and screws supplied,
secure the flue bend to the appliance flue spigot.

NOTE

Fit the internal (white) trim to the flue assembly
prior to connecting the flue pipe to the bend.
You must ensure that the entire flue system is
properly supported and connected.
Seal the flue assembly to the wall using cement
or a suitable alternative that will provide
satisfactory weatherproofing. The exterior trim can
now be fitted.

4.5.1.1 EXTENDING THE FLUE

Connect the bend – supplied with the terminal kit
– to the top of the boiler using clamp (supplied)
see fig. 7. The additional bends & extensions hav e
push-fit connections, 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 to the
maximum equivalent flue length) to the flue terminal
(see fig. 7 & 8).
The flue system should have a minimum of 1º;
maximum of 3° rise from the boiler to outside, to
ensure any condense fluid that forms, is allowed
to drain back to the appliance.

NOTE

When cutting an extension to the required length,
you must ensure that the excess is cut from the
plain end of the extension (see fig. 7 & 8). Remove
any burrs, and check that all 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.

“X”

30mm

“X” + 65mm = “Y”

Fig. 7A

“Y”

1-3 degree

4.5.2 CONCENTRIC VERTICAL FLUE

The appliance can be used with either the V ok era
condensing 60/100mm concentric flue system or
the optional 80/125mm concentric flue system.

NOTE

These instructions relate only to the Vokera
condensing 60/100mm concentric flue system.
For specific details on the installation of the 80/
125mm concentric flue system please refer to the
instructions supplied.
The vertical flue terminal can be connected directly
to the appliance flue outlet. Alternatively, an
extension or bend can be connected to the
appliance flue outlet if desired (see 4.4.2), however
if additional bends are fitted, a reduction must be
made to the maximum flue length (see table in
the next page).

Fig. 8

11

Supplied By www.heating spares.co Tel. [phone]

Reduction for bends

Bend
45° bend

90° bend

Ve rtical flue terminal and accessories

Part No.

530
531
532
523
524
525
526
527
528
529

Reduction in maximum flue length for each bend

0.5 metre

1.0 metre

Description

V ertical flue terminal
Pitched roof flashing plate
Flat roof flashing plate
90-degree bend
45-degree bends (pair)
500mm extension
1000mm extension
2000mm extension
T elescopic e xtension
Wall brac ket pack (5)

Using the dimensions given in fig. 9 as a reference,
mark and cut a 115mm hole in the ceiling and/or
roof.

“X”

12/15/20HE = 202mm
25/30/35HE = 218mm

“X”

Fig. 9

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.
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.

IMPORTANT

The vertical flue terminal is 1.0 metre in length
and cannot be cut; therefore it may be necessary
to adjust the height of the appliance to suit or use
a suitable extension.

Min-Max length
1000 mm

N/A
N/A
N/A
N/A
500mm
1000 mm
2000 mm
350/730mm
208mm

Connect the vertical flue assembly to the boiler
flue spigot using the 100mm clip, gasket, & screws
(supplied), ensuring the correct seal is made. The
flue support bracket (supplied with the vertical
flue kit) can now be fitted.
If the vertical flue requires extension/s or
additional bend/s, connect the required number
of flue extensions or bends (up to the maximum
equivalent flue length) between the boiler and
vertical flue assembly (see fig. 8).
Ensure that any horizontal sections of the flue
system have a minimum 1º; maximum 3º fall back
to the boiler (1º = 17mm per 1000mm)

NOTE

When cutting an extension to the required length,
you must ensure that the excess is cut from the
plain end of the extension (see fig. 8). Remove
any burrs, and check that any seals are located
properly.
You must ensure that the entire flue system is
properly supported and connected.

4.5.3 TWIN FLUE SYSTEM

The Voker a twin flue system enables greater flue
distances to be achieved (see 4.4.2) than that of
a concentric flue system. It can be used for
horizontal or vertical applications, howev er the twin
flue system must be converted to the dedicated
concentric flue kit for termination. It is essential
that the installation of the twin flue system be
carried out in strict accordance with these
instructions.

GUIDANCE NOTES ON TWIN FLUE
INSTALLA TION

• The flue must have a minimum 1º; maximum 3º
(1º = 17mm per 1000mm) fall 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.

• Ensure that the entire flue system is adequately
supported, use at least one bracket for each
extension.

• The entire flue system must be adequately
insulated to maintain heat within the flue system
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.

• The condensate drain pipe must be connected
in accordance with building regulations

Reduction for bends

Bend
45° bend
90° bend

Reduction in maximum flue length for each bend

1.0 metre

1.0 metre

12