VOKERA Vision 25C, Vision 30C User Instructions

Users Instructions

Installation &
Servicing
Instructions

THESE INSTRUCTIONS
TO BE RETAINED
BY USER

Vokèra is a licensed member of the Benchmark scheme
which aims to improve the standards of installation and
commissioning of domestic hot water systems in the UK.

Vision C

High efciency combi boiler

37

Users instructions

Things you should know Page

1.1 Gas appliances 1

1.2 Electrical supply 1

1.3 Guarantee registration card 1

1.4 Appliance Log Book (UK only) 1

1.5 How does it work? 1

1.6 Dimensions 1

1.7 Clearances required 1

1.8 Frost protection system 1

1.9 Appliance status indicators 1

Getting started Page

2.1 Before switching ON 6

2.2 Appliance controls 6

2.3 Lighting the boiler 6

2.4 Adjusting the heating temperature 6

2.5 Adjusting the hot water temperature 6

2.6 Explanation of features 6

2.7 Automatic temperature control 6

How to... Page

3.1 How to top-up the system pressure 6

3.2 How to reset the appliance 6

3.3 How to shut down the system for short periods 6

3.4 How to shut down the system for long periods 6

3.5 How to care for the appliance 6

What if... Page

4.1 What if I suspect a gas leak 7

4.2 What if I have frequently top-up the system 7

4.3 What if the appliance is due its annual service 7

4.4 What if I need to call an engineer 7

Installation and Servicing instructions

Design principles & operating sequence Page

1.1 Principle components 9

1.2 Mode of operation (at rest) 9

1.3 Mode of operation (heating) 9

1.4 Mode of operation (Hot water) 9

1.5 Safety devices 9

Technical data Page

2.1 Central heating 10

2.2 Domestic hot water 10

2.3 Gas pressures 10

2.4 Expansion vessel 10

2.5 Dimensions 10

2.6 Clearances 10

2.7 Connections 10

2.8 Electrical 10

2.9 Flue details (concentric 60-100) 10

2.9A Flue details (concentric 80-125) 10

2.9B Flue details (twin pipes) 10

2.10 Efciency 11

2.11 Emissions 11

2.12 Pump duty 11

General requirements (UK) Page

3.1 Related documents 12

3.2 Location of appliance 12

3.3 Gas supply 12

3.4 Flue system 12

3.5 Air supply 12

3.6 Water circulation 12

3.7 Electrical supply 13

3.8 Mounting on a combustible surface 13

3.9 Timber framed buildings 13

3.10 Inhibitors 13

3.11 Showers 13

General requirements (EIRE) Page
3A.1 Related documents 13
3A.2 Location of appliance 13
3A.3 Gas supply 13
3A.4 Flue system 13
3A.5 Air supply 14
3A.6 Water circulation 14
3A.7 Electrical supply 14
3A.8 Mounting on a combustible surface 14
3A.9 Timber framed buildings 14
3A.10 Inhibitors 14
3A.11 Showers 14
3A.12 Declaration of conformity 14

Installation Page

4.1 Delivery 15

4.2 Contents 15

4.3 Unpacking 15

4.4 Preparation for mounting the appliance 15

4.5 Fitting the ue 15

4.6 Connecting the gas & water 19

4.7 Electrical connections 19

Commissioning Page

5.1 Gas supply installation 20

5.2 The heating system 20

5.3 Initial lling of the system 20

5.4 Initial ushing of the system 20

5.5 Pre-operation checks 20

5.6 Initial lighting 20

5.7 Checking gas pressure & combustion analysis 20

5.8 Final ushing of the heating system 20

5.9 Setting the boiler operating temperature 20

5.10 Setting the system design pressure 20

5.11 Regulating the central heating system 21

5.12 Final checks 21

5.13 Instructing the user 21

Servicing Page

6.1 General 21

6.2 Routine annual servicing 21

6.3 Replacement of components 21

6.4 Component removal procedure 21

6.5 Pump assembly 22

6.6 Safety valve 22

6.7 Lower automatic air release valves 22

6.8 Water pressure switch 22

6.9 Flow thermistor 22

6.10 Return thermistor 22

6.11 Printed circuit board 22

6.12 Gas valve 23

6.13 Electrodes 23

6.14 Flue fan & mixer 23

6.15 Burner 23

6.16 Main heat exchanger 24

6.17 Automatic by-pass & DHW non-return valve 24

6.18 Expansion vessel removal 24

6.19 Condense trap removal 24

6.20 Flue collector removal 25

Checks, adjustments and fault nding Page

7.1 Checking appliance operation 26

7.2 Appliance modes of operation 26

7.3 Checking the CO2 & adjusting the valve 26

7.4 Combustion analysis test 27

7.5 Checking the expansion vessel 27

7.6 External faults 27

7.7 Electrical checks 27

7.8 Fault nding 28

7.9 Component values & characteristics 28

7.10 Adjustments 29

Wiring diagrams Page

8.1 External wiring 31

8.2 Other devices 31

L.P.G. instructions Page

10.1 Related documents 33

10.2 Technical data 33

10.3 Converting the appliance gas type 33

10.4 Gas supply 33

10.5 Gas supply installation 33

10.6 Checking the CO2 and adjusting the gas valve 33

Benchmark 35-36

1

USERS INSTRUCTIONS

1.1 GAS APPLIANCES

Gas Safety (Installation and Use) Regulation (UK).

In the interests of your safety and that of others it is a legal
requirement that all gas appliances are installed and correctly
maintained by a competent person and in accordance with the
latest regulations.

1.2 ELECTRICAL SUPPLY

Please ensure that this appliance has been properly connected
to the electrical supply by means of a double pole isolator or
un-switched socket, and that the correct size of fuse (3 AMP)

has been tted.

Warning: this appliance must be earthed!

1.3 GUARANTEE REGISTRATION CARD

Please take the time to ll out your guarantee registration card.

The completed warranty card should be posted within 30 days
of installation.

1.4 APPLIANCE LOG BOOK (UK only)

A logbook section can be found at the rear of the appliance
installation booklet. This important document must be completed
during the installation/commissioning of your boiler. All GAS
SAFE registered installers carry a GAS SAFE ID card, and have
a registration number. These details should be recorded in the
Benchmark logbook section within the installation booklet. You
can check your installers details by calling GAS SAFE direct on

08004085500. Failure to install and commission the appliance in
accordance with the manufacturers instructions may invalidate
the warranty. This does not affect your statutory rights.

1.5 HOW DOES IT WORK?

Your Vision boiler supplies heated water to your radiators and
hot water to your hot water taps. The central heating is con­trolled via a time clock and any thermostats that your installer

may have tted. The boiler will light when it receives a request

from the time clock via any thermostat that may be installed, or
whenever a hot water outlet (tap) is opened. Your Vision boiler
lights electronically and does not have a pilot light.
In the unlikely event of a fault developing with your boiler, the
supply of gas to the burner will be terminated automatically.

Dear Customer

Your Vokèra Vision boiler has been designed to meet and exceed the very latest standards in gas central heating technology,

and if cared for, will give years of reliable use and efciency.

Please therefore take some time to read these instructions carefully.

Do’s and Don’t’s

- Do ensure that the system pressure is periodically checked

- Do ensure that the boiler should not be used by children or unassisted disabled people

- Do ensure that you know how to isolate the appliance in an emergency

- Do ensure that you are familiar with the appliance controls

- Do ensure that your installer has completed the appliance log book section

- Do not attempt to remove the appliance casing or gain internal access

- Do not hang clothes etc. over the appliance

- Do not forget to have the appliance serviced annually.

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 Vokèra customer
services.

INTRODUCTION

1.6 DIMENSIONS

1.7 CLEARANCES REQUIRED

ABOVE 150 mm
BELOW 150 mm
LEFT SIDE 12 mm
RIGHT SIDE 12 mm
FRONT 600 mm

Vision 25C - 30C

HEIGHT 715 mm
WIDTH 405 mm
DEPTH 248 mm

1.8 FROST PROTECTION SYSTEM

The Vision is equipped with a built-in frost protection system,
this enables the boiler to over-ride the time controls – even if
switched off – and operate the burner and/or pump, should
the temperature drop below 5

0

C for the main and for the DHW
line. In particular the burner will be in ON status until the main
temperature reaches 35°C for CH appliance and 55°C for
DHW appliance. Please note that the frost protection system
is designed to protect the appliance only, should frost protec­tion be required for the heating system, additional controls
may be required.

NOTE

The frost protection system is reliant on the appliance having a
permanent electrical supply, and being in a non-fault condition.

1.9 APPLIANCE STATUS INDICATORS

Your boiler is equipped with a large LCD display that indicates
the appliance operating status.

1. THINGS YOU SHOULD KNOW

2

Fig. 1

HOT WATER TEMPERATURE SELECTOR

Move the selector clockwise to increase the hot water outlet temperature, or counter-clockwise to reduce the temperature

PRESSURE GAUGE

Ensure the system pressure is set correctly (minimum 0.5-bar)

MODE SELECTOR SWITCH/HEATING TEMPERATURE SELECTOR

Mode selector switch:

Hot water only - Select this position if you want the boiler to supply hot
water only (no heating)

Hot water temperature selector: move the selector clockwise to increase
the DHW outlet temperature, or counter-clockwise to reduce the temperature
(range: 37°C-60°C)
The display shows the temperature values.

Boiler at OFF/standby - Select this position when you want the boiler to
be switched off for short periods (days) or if the boiler requires to be reset

The display shows “- -”.

Heating & hot water - Select this position when you want the boiler to re­spond to a heating and hot water request from the time-clock programmer

Heating temperature selector: move the selector clockwise to increase the
heating outlet temperature, or counter-clockwise to reduce the temperature
(range: 40°C-80°C for standard central heating).
The automatic temperature control function (SARA) is set within the blank
bullet points.
The display shows the temperature values.

Pressure gauge shows the current pressure of your heating system, the
gauge should be set between 1 and 1.5 BAR. When the appliance is oper­ating the gauge may rise or fall slightly, this is quite normal. The minimum

permissible level for the safe and efcient operation of the appliance is 0.5

BAR. Should the pressure fall below 0.5 BAR, the boiler may lockout.

correct pressure

value

MODE SELECTOR SWITCH

HEATING TEMPERATURE SELECTOR

PRESSURE GAUGE

HOT WATER

TEMPERATURE

SELECTOR

DIGITAL WEEKLY CLOCK AND

BOILER STATUS DISPLAY

DHW pre-heat function - Turning the domestic hot water temperature
adjustment knob to the symbol activates the pre-heating function. Bring the
domestic hot water temperature adjustment knob back to the required po­sition. The activation of this function is indicated on display with the P icon
ON. This function keeps the water in the domestic hot water exchanger hot,
to reduce standby times when a request is made. The display shows the
delivery temperature of the heating water or the domestic hot water, accor­ding to the current request. To deactivate the pre-heat function, rotate the
domestic hot water temperature adjustment knob back to the symbol. Bring
the domestic hot water temperature adjustment knob back to the required
position. This function cannot be activated when the boiler is OFF: function
selector to OFF position.

CLOCK SETTING

BUTTONS

3

DIGITAL WEEKLY CLOCK

Fig. 2

Button/Icon Main Function Secondary Function

Used to set/adjust
time of day, and
day of week

N/A

Use to “advance”
the heating to an
ON period

Use to increase values when
setting clock & day of week.
Use to program ON periods
for heating pattern.

Use to “advance”
the heating to an
OFF period

Use to decrease values
when setting clock & day of
week. Use to program OFF
periods for heating pattern.

Use to change
mode of operation

Use when installing a user

dened heating program.

Symbol/Icon Description/Function

Used to show current day of week

(ashing)

Displayed when the ADVANCE-ON fun­ction is active

Displayed when the ADVANCE-OFF fun­ction is active

Displays current minutes past the hour

Displays current hour of the day

24-hour clock in 30 minute segments; lar­ge segments represent hour mark, small
segments represent half-past the hour;

ashing segment represents actual time

Symbol/Icon Description

Displayed when heating mode is active

Displayed when hot water mode is active

Displayed when frost protection function is ac­tive

Displayed when hot-water pre-heat function is
enabled. Flashes when functioning

Displayed if an alarm or fault has been detected

Displayed when low system pressure has been
detected

Displayed when an external sensor is connected
to the boiler

Displayed if an ignition fault has been detected

Displayed when the burner is ON

4

BUILT-IN CLOCK

The Vision 25C & 30C incorporate a built-in digital clock and
multi-inf mative LCD display.

1.1

The digital clock is pre-programmed with a default heating

pattern (see table 1 below); however this can be modied to

suit individual needs (see 1.4).

Pre-programmed Heating Pattern

Day

am pm

ON OFF ON OFF

Monday 06:30 08:30 4:30 10:30

Tuesday 06:30 08:30 4:30 10:30

Wednesday 06:30 08:30 4:30 10:30

Thursday 06:30 08:30 4:30 10:30

Friday 06:30 08:30 4:30 10:30

Saturday 08:00 10:00 4:00 11:00

Sunday 08:00 10:00 4:00 11:00

1.2 MODES OF OPERATION

The built-in digital clock has the following modes of operation:

1. AUTO ON / AUTO OFF – where the clock uses the pro-

grammed heating pattern (default or user dened) to switch

the heating ON & OFF at pre-selected times (see Fig.1).

2. MAN ON – where the clock is set to provide heating con-

stantly ON (in this mode the default or user dened heating

pattern is ignored).

3. MAN OFF – where clock is set to have the heating constan-

tly OFF (in this mode the default or user dened heating

pattern is ignored).

4. ADVANCE ON – where the pre-programmed heating pat­tern is advanced to the next ON period (this function can
only be used when the clock is in the AUTO OFF mode)

5. ADVANCE OFF - where the pre-programmed heating pat­tern is advanced to the next OFF period (this function can
only be used when the clock is in the AUTO ON mode).

1.3 SETTING THE TIME AND DAY

Ensure that the boiler is electrically supplied.

1. Press and hold the clock button for 3-seconds; the

right hand digits (minutes) will ash continuously.

2. Press the up arrow button to increase the minutes va-

lue or press the

down arrow button to decrease the

value.

3. Once the correct minutes value is displayed, press the
clock button to store this setting and move to the hours
value.

4. Press the up arrow button to increase the hours value

or press the

down arrow button to decrease the value.

5. Once the correct hours value is displayed press the
clock button to store this setting and move to the day of
week value.

6. Press the up arrow button to move forward to the cor­rect day of week (1 = Monday – 7 = Sunday)or press the

down arrow button to move back to the correct day of

week..

7. Once the correct day of week is displayed press the
clock button to store this setting and complete the time /
day of week, setting procedure.

NOTE, the time of day is shown on the display, and is also

indicated on the 24-segmented display as a ashing segment.

1.4 CHANGING THE HEATING PATTERN

The built-in clock is pre-programmed with a default heating
pattern (see Fig.1), however this can be changed to a user

dened heating pattern.

To insert a new heating pattern or change and existing one,
proceed as follows:

1. Press and hold the program button for 3-seconds

2. The day of week segment ashes to indicate which day of

week is being programmed

3. Use the up arrow button to select the required ON

periods and use the down arrow button to select the
OFF periods

NOTE, each segment represents 30-minutes, the large seg­ments are hour indicators, and the small segments are half­hour indicators.

4. When the ON and OFF selections have been made for the
particular day (relevant day of week is displayed by the

appropriate number 1 to 7) press the

program button

to store the new settings and move to the next day.

NOTE
If you want to duplicate the new settings for subsequent days,
e.g. same heating pattern for Monday to Friday, press and

hold the

program button for 3-seconds each time the ap-

propriate day of week is displayed.

EXAMPLE
Day of week = 1 (Monday) Insert the new ON & OFF settings

(step 3 above), press the

button, day of week now shows

2 (Tuesday). Press the button for 3-seconds, Monday’s
settings are now duplicated for Tuesday; repeat as required.

5. If you require to change the settings for subsequent days,
repeat steps 3 & 4 above

6. Once programming has been completed, continue to press

and release the program button until you exit the pro­gramming function (normal display is resumed).

1.5 ADVANCE FUNCTION

When the clock is in the AUTO ON or AUTO OFF mode, it’s
possible to advance the current setting (ON or OFF) to the
next programmed setting (ON or OFF), e.g. if the clock is in
AUTO OFF mode it’s possible to advance to the next AUTO
ON setting.

1.5.1 ADVANCE ON

Press and hold the

up arrow button for 3-seconds, the

display changes from AUTO OFF to AUTO ON and the
icon is displayed.

NOTE, the ADVANCE ON function can be cancelled by mo-

mentarily pressing the

button.

NOTE, when the ADVANCE ON function is enabled, the hea­ting will remain ON until the next scheduled OFF period.

1.5.2 ADVANCE OFF

Press and hold the

down arrow button for 3-seconds, the

display changes from AUTO ON to AUTO OFF and the
icon is displayed.

NOTE, the ADVANCE OFF function can be cancelled by mo-

mentarily pressing the

button.

Table 1

5

NOTE, when the ADVANCE OFF function is enabled, the hea­ting will remain OFF until the next scheduled ON period.

1.6 MODE OF OPERATION

To change the mode of operation (AUTO to MAN) momenta-

rily press the

button; the display will show the following:

• AUTO OFF Heating is in an OFF period according to the

programmed heating pattern

• AUTO ON Heating is in an ON period according to the

programmed heating pattern

• MAN OFF Heating is being controlled manually and is

switched constantly OFF

• MAN ON Heating is being controlled manually and is

switched constantly ON.

1.7 RESET HEATING PROGRAM TO DEFAULT VA­LUES

The heating pattern can be reset to the default values (see

g.1) by pressing and holding both

buttons simulta-

neously for 3-seconds.

NOTE

This cancels any previously input, user dened settings

6

2.1 BEFORE SWITCHING ON

Before switching the appliance on, please familiarise yourself
with:

- how to isolate the appliance from the gas, water, and electricity
supplies;

- how to check and top-up – if necessary – the system water
pressure;

- the time clock or programmer (if tted);

- any external thermostats and their functions;

- the appliance controls.

2.2 APPLIANCE CONTROLS (see g. 1)

The appliance controls are situated on the lower front of the
appliance. The appliance controls include:

- pressure gauge;

- appliance mode selector;

- temperature selectors;

- integral time clock.

NOTE

The appliance frost protection is active in all the boiler modes.
The temperature selectors can be used to vary the temperature
of the water that circulates around your radiators and the water

that ows from your hot water taps. The temperature range is

adjustable between 40

o

C and 80oC for the central heating, and

between 37

o

C and 60oC for the hot water.

The display normally shows the current time.
Refer to the main appliance status table for fault indicator and
boiler status.
The integral digital time clock is used to switch the heating on
and off at pre-determined intervals.

2.3 LIGHTING THE BOILER

Ensure the gas and electrical supply to the boiler are
turned on.

Turn the mode selector switch to the ON position. When there
is a request for heating or hot water via the time clock or pro­grammer, the boiler will begin an ignition sequence. When the

appliance reaches the CH set temperature, the burner will go
off for a minimum period of approximately 3 minutes.
When the programmer/time clock or external thermostats

heating request has been satised, the appliance will switch

off automatically.

2.4 ADJUSTING THE HEATING TEMPERATURE

Rotate the temperature selector – clockwise to increase, counter­clockwise to decrease – to the desired temperature setting. The
temperature can be set from a minimum of 40°C to a maximum
of 80°C (if standard CH mode is selected).

2.5 ADJUSTING THE HOT WATER TEMPERA­TURE

Rotate the temperature selector – clockwise to increase,
counter-clockwise to decrease – to the desired temperature
setting. The temperature can be set from a minimum of 37°C
to a maximum of 60°C. If the temperature at the outlet is still

not sufciently hot enough, it may be necessary to reduce the
ow of water at the hot water outlet (tap).

NOTE

If the appliance fails to ignite during the ignition sequence, it
will enter a lockout condition. Should this occur, please allow

a period of at least two minutes before re-setting the appliance.

2.6 EXPLANATION OF FEATURES

Although the Vokèra Vision has been designed for simplicity of
use, it utilises the latest in boiler technology, enabling a host of

functions to be carried out simultaneously.

2.7 AUTOMATIC TEMPERATURE CONTROL

The automatic temperature control function (SARA), permits
the boiler (when the heating temperature selector is set within
the blank bullet points to automatically adjust (raise) the heating.
The activation and the disable of the function is visualized on
the display if the heating temperature is selected between 55°

-65°C.

2. GETTING STARTED

3.1 HOW TO TOP-UP THE SYSTEM PRESSURE

(g. 1-2)

The system pressure must be checked periodically to ensure the
correct operation of the boiler. The needle on the gauge should
be reading between 1 and 1.5 BAR when the boiler is in an off
position and has cooled to room temperature. If the pressure
requires ‘topping-up’ use the following instructions as a guide.

- Locate the lling valve connections (usually beneath the
boiler, see g. 3).

- Attach the lling loop to both connections.

- Open the lling valve slowly until you hear water entering the

system.

- Close the lling valve when the pressure gauge (on the boiler)
reads between 1 and 1.5 BAR (see g. 1).

- Remove the lling loop from the connections.

3.2 HOW TO RESET THE APPLIANCE

When the fault code is displayed, the appliance will require to
be reset manually. Before resetting the boiler, check what action
is required to be taken, using the information on the fault code
table below. Allow a period of two minutes to elapse before rotate
the mode selector knob across the

position (see g. 1).

IMPORTANT

If the appliance requires to be reset frequently, it may be indica­tive of a fault, please contact your installer or Vokèra Customer
Services for further advice.

3. HOW TO...

Fig. 3

control

valve

temporary

connection

control

valve

supply pipe

double

check valve

ow/return

pipe

3.3 HOW TO SHUT DOWN THE SYSTEM FOR
SHORT PERIODS

The system and boiler can be shut down for short periods by
simply turning the time clock to the off position. It is also advis­able to turn off the main water supply to the house.

3.4 HOW TO SHUT DOWN THE SYSTEM FOR
LONG PERIODS

If the house is to be left unoccupied for any length of time –
especially during the winter – the system should be thoroughly
drained of all water. The gas, water, and electricity supply to
the house should also be turned off. For more detailed advice
contact your installer.

3.5 HOW TO CARE FOR THE APPLIANCE

To clean the outer casing use only a clean damp cloth. Do not
use any scour­ers or abrasive
cleaners.

7

4.1 WHAT IF I SUSPECT A GAS LEAK

If you suspect a gas leak, turn off the gas supply at the gas
meter and contact your installer or local gas supplier. If you

require further advice please contact your nearest Vokèra ofce.

4.2 WHAT IF I HAVE FREQUENTLY TO TOP-UP
THE SYSTEM

If the system regularly requires topping-up, it may be indicative
of a leak. Please contact your installer and ask him to inspect
the system.

4.3 WHAT IF THE APPLIANCE IS DUE ITS AN­NUAL SERVICE

Advice for tenants only

Your landlord should arrange for servicing.

FAULT CODES

4. WHAT IF...

Advice for homeowners
Please contact Vokèra Customer Service (0844 3910999 (UK)
or 056 7755057 (ROI) if you would prefer a Vokèra service

engineer or agent to service your appliance. Alternatively your
local GAS SAFE registered engineer may be able to service
the appliance for you.

4.4 - WHAT IF I NEED TO CALL AN ENGINEER

If you think your boiler may have developed a fault, please contact
your installer or Vokèra Customer Services (0844 3910999 (UK)
or 056 7755057 (ROI) have all your details to hand including
full address and postcode, relevant contact numbers, and your
completed appliance log book.

ALARM CODE CAUSE ALARM TYPE ACTION

_St

AUTOSTOP Final Call engineer

_CL

CALL FOR SERVICE Temporary then

Final

Call engineer

A01

Ignition failure, ame not sensed,

internal fault

Final Reset, check appliance operation

A02

Limit thermostat fault Final Reset, check appliance operation

A03

Fan tacho signal fault Final Reset check appliance operation,

check fan

A04

Insufcient system water pressure Final Check/rell system pressure, reset,

check appliance operation

A06

DHW thermistor fault Temporary Check DHW thermistor

A07

Primary (ow) thermistor fault Temporary Check primary thermistor, check wiring

Primary (ow) thermistor over tempe-

rature

Temporary then
Final

Reset, check appliance operation

Temperature differential Final Reset, check appliance operation,

check thermistors

A08

Return thermistor fault Temporary Check return thermistor, check wiring

Return thermistor over temperature Temporary then

Final

Reset, check appliance operation

Temperature differential inverted Final Reset, check pump, ensure there is

sufcient circulation around heating

circuit/s

A09

Flue thermistor or ue thermistor

counter fault

Temporary Check ue thermistor counter at power

on, check ue thermistor, check wiring

Flue thermistor over temperature Final Reset, check appliance operation

A77

Low temperature thermostat fault Temporary Check low temperature thermostat

Adj

Calibration Na None

ACO

Service operation Na None







Purge cycle mode active Na None

P

Preheating function active Na None

P blinking

Preheating function running Na None

Flame ON Na None

Hours Stand-by Na None

- - OFF Na None

8

The Vision comprises a range of high-efciency combination

boilers with outputs to DHW of 25kW and 29kW respectively.
These appliances – by design – incorporate electronic ignition,
circulating pump, expansion vessel, safety valve, pressure
gauge and automatic by-pass.
The Vision range is produced as room sealed, category II2H3P
appliances, suitable for internal wall mounting applications only.

Each appliance is provided with a fan powered ue outlet with

an annular co-axial combustion air intake that can be rotated
– horizontally – through 360 degrees for various horizontal
or vertical applications. The Vision can also be used with the

Vokèra twin ue system.

The Vision is approved for use with C13 & C33 type ue ap-

plications.
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 Vokèra
customer services.

Fig. 4

General layout

1 Domestic hot water heat exchanger
2 Drain valve
3 Three porte valve actuator
4 Safety valve
5 Pump
6 Bottom auto air vent (AAV)
7 Main heat exchanger
8 Flues thermistor (NTC)
9 Fan assembly with mixer
10 Silencer
11 Flue gas analysis test point
12 Flue outlet & air intake
13 Ignition transformer
14 Top AAV+De-aerator
15 Spark Electrode
16 Sensing Electrode
17 Flow thermistor (NTC) - High limit thermostat
18 Expansion vessel
19 Pressure switch
20 Return thermistor (NTC)
21 Gas valve
22 Domestic hot water sensor
23 Condense trap

24 DHW ow switch

R Heating return connection

F Heating ow connection

G Gas connection
O Hot water outlet
I Cold water inlet

INTRODUCTION

INSTALLATION AND SERVICING INSTRUCTIONS

R F G O I

9

1.1 PRINCIPLE COMPONENTS

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

•

Aluminium heat exchanger

• Electronic ignition with ame supervision

• Integral high-head pump

• Fan

• Expansion vessel

• Water pressure switch

• Flue 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:

•

frost-protection system – the frost-protection system protects

the appliance against the risk of frost damage both for CH
and DHW. For CH line, if the main temperature falls to 5°C,
the appliance will function on minimum power until the tem­perature on main reaches 35°C.

Moreover if the DHW temperature falls to 5°C, the appliance

will function on minimum power until the temperature on main
reaches 55°C.

•

anti-block function – the anti-block function enables the pump

and divertor valve actuator to be energised for short periods,
when the appliance has been inactive for more than 24-hours.

1.3 MODE OF OPERATION (Heating)

When there is a request for heat via the 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 circuit to ensure ame stability

at the burner. Once successful ignition has been achieved, the
electronic circuitry increases the gas rate to 75% for a period of
15 minutes. Thereafter, the boiler’s output will either be increase
to maximum or modulate to suit the set requirement. When
the appliance reaches the desired 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 satised the appliance

pump and fan may continue to operate to dissipate any residual
heat within the appliance.

1.4 MODE OF OPERATION (Hot water)

When there is a request for DHW via a hot water outlet or tap,
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 circuit to ensure ame stabil­ity at the burner. Once successful ignition has been achieved,
the electronic circuitry increases the gas rate to maximum or
will modulate output to stabilise the temperature.
In the event of the appliance exceeding the desired temperature
(set point) the burner will shut down until the temperature drops.

When the request for DHW has been satised the appliance

pump and fan may continue to operate to dissipate any residual
heat within the appliance.

Fig. 5

Expansion

vessel

Safety

valve

Pump

Return

temperature

sensor

Main heat

exchanger

Bottom

AAV

Pressure

switch

DHW heat
exchanger

Diverter

valve

Drain
valve

DHW tem-

perature

sensor

Flow temperature

sensor

Top AAV

Automatic

by-pass

DHW

non return

valve

CH

return

CH

ow

DHW

inlet

DHW
outlet

Flow regu-

lator

DHW ow

switch

SECTION 1 - DESIGN PRINCIPLES AND OPERATING SEQUENCE

1.5 SAFETY DEVICES

When the appliance is in use, safe operation is ensured by:

•

a water pressure switch that monitors system water pressure

and will de-activate the pump, fan, and burner should the
system water pressure drop below the rated tolerance;

•

fan speed sensor to ensure safe operation of the burner;

• a high limit thermostat that over-rides the temperature control
circuit to prevent or interrupt the operation of the burner;

•

ame sensor that will shut down the burner when no ame

signal is detected;

•

ue sensor;

• a safety valve which releases excess pressure from the
primary circuit.

10

SECTION 2 - TECHNICAL DATA

2.1 Central Heating Vision 25C Vision 30C

Heat input (kW) 20.00 25.00

Maximum heat output (kW) 60/80°C 19.50 24.45

Minimum heat output (kW) 60/80°C 4.91 5.90

Maximum heat output (kW) 30/50°C 20.84 26.23

Minimum heat output (kW) 30/50°C 5.36 6.40

Minimum working pressure 0.25-0.45 bar

Maximum working pressure 2.5 bar

Minimum ow rate 350 l/h

2.2 Domestic Hot Water Vision 25C Vision 30C

Heat input (kW) 25.00 29.00

Flow Rate: ΔT35°C 10.20 12.0

Maximum inlet pressure 6 bar

Minimum inlet pressure 0.15 bar

Minimum ow rate 2 l/min

2.3 Gas Pressures Vision 25C Vision 30C

Inlet pressure (G20) 20.0 mbar 20.0 mbar

Heating maximum gas rate (m3/hr) 2.12 2.64

DHW maximum gas rate (m3/hr) 2.64 3.07

Minimum gas rate (m3/hr) 0.53 0.63

Injector size (mm) 5.1 5.6

Silencer ange (ø mm) (tted) 31 -

2.4 Expansion Vessel Vision 25C Vision 30C

Capacity 8 litres

Maximum system volume 74 litres

Pre-charge pressure 1 bar

2.5 Dimensions Vision 25C Vision 30C

Height (mm) 715

Width (mm) 405

Depth (mm) 248

Dry weight (kg) 27 28

2.6 Clearances Vision 25C Vision 30C

Sides 12mm

Top 150mm from casing or 25mm above ue elbow (whichever is applicable)

Bottom 150mm

Front 600mm

2.7 Connections Vision 25C Vision 30C

Flow & return 22mm

Gas 15mm

DHW hot & cold 15mm

Safety valve 15mm

Condense

21mm

2.8 Electrical Vision 25C Vision 30C

Power consumption (Watts) 110 11 9

Voltage (V/Hz) 230/50

Internal fuse 3.15A T (for PCB) - 3.15A F (for connections block)

External fuse 3A

2.9 Flue Details (concentric 60-100) Vision 25C Vision 30C

Maximum horizontal ue length (60/100mm) 5.85m 4.85m

Maximum vertical ue length (60/100mm) 6.85m 5.85m

2.9A Flue Details (concentric 80-125) Vision 25C Vision 30C

Maximum horizontal ue length (80/125mm) 15.3m 12.8m

Maximum vertical ue length (80/125mm) 20.3m

17.8m

2.9B Flue Details (twin pipes) Vision 25C Vision 30C

Maximum horizontal ue length (80mm/80mm) 45m/45m 40m/40m

Maximum vertical ue length (80mm/80mm) 45m/45m 40m/40m