VOKERA Excel 25, Excel 29 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.
Excel
High efciency combi boiler
Excel 25 G.C. N° 47-364-12
Excel 29 G.C. N° 47-364-13
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 3
2.2 Appliance controls 3
2.3 Lighting the boiler 3
2.4 Adjusting the heating temperature 3
2.5 Adjusting the hot water temperature 3
2.6 Explanation of features 3
2.7 Automatic temperature control 3
How to... Page
3.1 How to top-up the system pressure 3
3.2 How to reset the appliance 3
3.3 How to shut down the system for short periods 3
3.4 How to shut down the system for long periods 3
3.5 How to care for the appliance 3
What if... Page
4.1 What if I suspect a gas leak 4
4.2 What if I have frequently top-up the system 4
4.3 What if the appliance is due its annual service 4
4.4 What if I need to call an engineer 4
Setting the Vokèra Page
5.1 Setting the Vokèra mechanical clock 4
Installation and Servicing instructions
Design principles & operating sequence Page
1.1 Principle components 6
1.2 Mode of operation (at rest) 6
1.3 Mode of operation (heating) 6
1.4 Mode of operation (Hot water) 6
1.5 Safety devices 6
Technical data Page
2.1 Central heating 7
2.2 Domestic hot water 7
2.3 Gas pressures 7
2.4 Expansion vessel 7
2.5 Dimensions 7
2.6 Clearances 7
2.7 Connections 7
2.8 Electrical 7
2.9 Flue details (concentric) 7
2.9A Flue details (twin pipes) 7
2.9B Flue details (80/125) 7
2.10 Efciency 7
2.11 Emissions 7
2.12 Pump duty 8
General requirements (UK) Page
3.1 Related documents 9
3.2 Location of appliance 9
3.3 Gas supply 9
3.4 Flue system 9
3.5 Air supply 9
3.6 Water circulation 9
3.7 Electrical supply 10
3.8 Mounting on a combustible surface 10
3.9 Timber framed buildings 10
3.10 Inhibitors 10
3.11 Showers 10
General requirements (EIRE) Page
3A.1 Related documents 10
3A.2 Location of appliance 10
3A.3 Gas supply 10
3A.4 Flue system 10
3A.5 Air supply 11
3A.6 Water circulation 11
3A.7 Electrical supply 11
3A.8 Mounting on a combustible surface 11
3A.9 Timber framed buildings 11
3A.10 Inhibitors 11
3A.11 Showers 11
3A.12 Declaration of conformity 11
Installation Page
4.1 Delivery 12
4.2 Contents 12
4.3 Unpacking 12
4.4 Preparation for mounting the appliance 12
4.5 Fitting the ue 12
4.6 Connecting the gas & water 15
4.7 Electrical connections 16
Commissioning Page
5.1 Gas supply installation 17
5.2 The heating system 17
5.3 Initial lling of the system 17
5.4 Initial ushing of the system 17
5.5 Pre-operation checks 17
5.6 Initial lighting 17
5.7 Checking gas pressure & combustion analysis 17
5.8 Final ushing 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 18
5.12 Final checks 18
5.13 Instructing the user 18
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 19
6.6 Safety valve 19
6.7 Lower automatic air release valves 19
6.8 Water pressure switch 19
6.9 Flow thermistor 19
6.10 Return thermistor 19
6.11 Printed circuit board 19
6.12 Gas valve 20
6.13 Electrodes 20
6.14 Flue fan & mixer 20
6.15 Burner 20
6.16 Main heat exchanger 21
6.17 Automatic by-pass & DHW non-return valve 21
6.18 Expansion vessel removal 21
6.19 Condense trap removal 21
6.20 Flue collector removal 22
Checks, adjustments and fault nding Page
7.1 Checking appliance operation 23
7.2 Appliance modes of operation 23
7.3 Checking the CO2 & adjusting the valve 23
7.4 Combustion analysis test 24
7.5 Checking the expansion vessel 24
7.6 External faults 24
7.7 Electrical checks 24
7.8 Fault nding 25
7.9 Component values & characteristics 25
Wiring diagrams Page
8.1 External wiring 26
8.2 Typical control applications 26
8.3 Other devices 26
8.4 Vokèra lower cover mechanical clock 26
L.P.G. instructions Page
10.1 Related documents 28
10.2 Technical data 28
10.3 Converting the appliance gas type 28
10.4 Gas supply 28
10.5 Gas supply installation 28
10.6 Checking the CO2 and adjusting the gas valve 28
Benchmark 30-31
1
USERS INSTRUCTIONS
1.1 GAS APPLIANCES
Gas Safety (Installations and Use) Regulations (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 COMMISSIONING CHECKLIST
(UK only)
A checklist 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 commissioning checklist 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 will invalidate the warranty.
This does not affect your statutory rights.
1.5 HOW DOES IT WORK?
Your Excel 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 Excel 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 Excel 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 efciency.
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
1.8 FROST PROTECTION SYSTEM
The Excel 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 3 status LED indicators, the Green
LED indicates that the ame is present, the Red LED indicates
the appliance has detected a fault, whilst the Yellow LED indicates that there is Servicing operation in progress.
1. THINGS YOU SHOULD KNOW
Excel 25-29
HEIGHT 715 mm
WIDTH 405 mm
ABOVE 150 mm
BELOW 150 mm
LEFT SIDE 12 mm
RIGHT SIDE 12 mm
FRONT 600 mm
2
Fig. 1
BOILER STATUS LED
Green LED Boiler is working/responding to a heating/hot water request
Red LED Boiler has identied a fault and has failed-safe. Refer to instructions on how to reset
Yellow LED Service operation
DHW 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:
MODE SELECTOR
SWITCH
RED LED
GREEN LED
HEATING
TEMPERATURE
SELECTOR
HYDROMETRE
DHW
TEMPERATURE
SELECTOR
YELLOW LED
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 heating outlet temperature,
or counter-clockwise to reduce the temperature (range:
37°C-60°C)
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
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 position 5 and 7.
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 efcient operation of the appliance
is 0.5 BAR. Should the pressure fall below 0.5 BAR, the
boiler may lockout.
correct
pressure
value
3
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 selector;
- burner ON mode (green);
- fault indicator (red);
- servicing mode indicator (yellow)
- optional integral time clock/programmer (if tted).
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 3 LED normally shows the operating temperature of the
appliance.
When the status indicator (Green) is lit it indicates that the
ame is present and the burner is ON.
When the fault indicator (Red) is lit it indicates that the appliance
has identied a possible fault and performed a safety lockout.
When the fault indicator (Yellow) is lit it indicates that there
is a Servicing operation in progress.
The integral time clock (when tted) can be 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 satised, the appliance will switch
off automatically.
2.4 ADJUSTING THE HEATING 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 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 sufciently 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 Excel 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
4 and 6 sector) to automatically adjust (raise) the heating.
The activation and the disable of the function is visualized by
blinking the green led.
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. 2).
- 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 red fault LED is illuminated, 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. 2
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.
4
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 ofce.
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.
5.1 - SETTING THE VOKÈRA MECHANICAL
CLOCK
If your boiler has been installed with the Vokèra mechanical
clock, it can be used and adjusted as follows:
Setting the time
The time of day can be set by grasping the outer edge of the
black dial and turning it in a clockwise direction until the correct
time is in line with the white pointer.
Setting the “switching times”
The “ON” periods are set by sliding the black tappets, adjacent to the time periods required, to the outer edge of the dial.
The tappets that remain at the centre of the dial will be the
“OFF” periods.
The smallest switching time (ON or OFF) is 15 minutes.
To select “AUTO” mode move the selector switch in central
position.
To select “ON” mode move the selector switch in the bottom
position.
To select “OFF” mode move the selector switch in the upper
position.
APPLIANCE STATUS LED AND FAULT CODES
Fig. 3
4. WHAT IF...
5. SETTING THE VOKÈRA...
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 type Led RED Led YELLOW Led GREEN Action
Purge cycle mode active NA BLINKING BLINKING BLINKING
Alarm high limit thermostat Final BLINKING OFF OFF Reset appliance.
Call engineer if fault re-occurs
Alarm system water pressure Final ON OFF ON Check/refill system pressure,
reset, check.
Call engineer if fault re-occurs.
Alarm safety shutdown and/or Final internal
fault
ON OFF OFF Reset appliance.
Call engineer if fault re-occurs.
Temporary fault Temporary OFF OFF BLINKING None
Service operation NA OFF BLINKING OFF None
Flame ON NA OFF OFF ON None
Fault sensors Final BLINKING OFF BLINKING Reset appliance.
Call engineer if fault re-occurs
Boiler stand-by NA OFF OFF BLINKING None
AUTO
ON
OFF
5
All installers are asked to follow the Benchmark Scheme by
adhering to the Code of Practise, which can be obtained from
www.centralheating.co.uk.
The Excel comprises a range of high-efciency 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 Excel 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 Excel can also be used with the
Vokèra twin ue system.
The Excel 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
6
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 satised 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 satised 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.
7
2.1 Central Heating Excel 25 Excel 29
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 Excel 25 Excel 29
Heat input (kW) 25.00 29.00
Flow Rate: ΔT35°C 10.20 l/min 12.0 l/min
Maximum inlet pressure 6 bar
Minimum inlet pressure 0.15 bar
Minimum ow rate 2 l/min
2.3 Gas Pressures Excel 25 Excel 29
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 Excel 25 Excel 29
Capacity 8 litres
Maximum system volume 74 litres
Pre-charge pressure 1 bar
2.5 Dimensions Excel 25 Excel 29
Height (mm) 715
Width (mm) 405
Depth (mm) 250
Dry weight (kg) 28 29
2.6 Clearances Excel 25 Excel 29
Sides 12mm
Top 150mm from casing or 25mm above ue elbow (whichever is applicable)
Bottom 150mm
Front 600mm
2.7 Connections Excel 25 Excel 29
Flow & return 22mm
Gas 15mm
DHW hot & cold 15mm
Safety valve 15mm
Condense
21mm
2.8 Electrical Excel 25 Excel 29
Power consumption (Watts) 11 0 119
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) Excel 25 Excel 29
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) Excel 25 Excel 29
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) Excel 25 Excel 29
Maximum horizontal ue length (80mm/80mm) 45m/45m 40m/40m
Maximum vertical ue length (80mm/80mm) 45m/45m 40m/40m
SECTION 2 - TECHNICAL DATA
8
2.10 Efciency Excel 25 Excel 29
SEDBUK (%) 90.0 90.2
2.11 Emissions Excel 25 Excel 29
CO2 @ maximum output (%) 9.0 9.0
CO2 @ minimum output (%) 9.5 9.5
CO @ maximum output (ppm) 180 160
CO @ minimum output (ppm) 20 20
NOx rating class 5 class 5
Fig. 6
2.12 PUMP DUTY
Fig. 6 shows the ow-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
o
C temperature differential.
Fig. 7
Flow rate (l/h)
Residual head (x 100 mbar)
1st speed
2nd speed
3rd speed
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
0 100 200 300 400 500 600 700 800 900 1000
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 (60mm for 80/125 - 5” ue)
H From internal/external corner 25 mm (60mm for 80/125 - 5” ue)
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 ashing As determined by the xed collar
of the vertical terminal
R To the side of a boundary 300 mm
S To the side of an opening or window on a pitched roof 600 mm
T Below an opening or window on a pitched roof 2000 mm
V From a vertical terminal to an adjacent opening (window, air-brick, etc.) (call Vokera technical for advice)
W From a vertical terminal to an adjacent vertical terminal 300 mm (only if both terminals are the same hight)
9
SECTION 3 - GENERAL REQUIREMENTS (UK)
This appliance must be installed by a competent person in ac-
cordance 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.
BS 5440 PART 1 FLUES
BS 5440 PART 2 FLUES & VENTILATION
BS 5449 PART 1 FORCED CIRCULATION HOT WATER SYSTEMS
BS 5546 INSTALLATION OF GAS HOT WATER SUPPLIES FOR DOMESTIC PURPOSES
BS 6798 INSTALLATION OF BOILERS OF RATED INPUT NOT EXCEEDING 60kW
BS 6891 LOW PRESSURE INSTALLATION PIPES
BS 7074 PART 1 APPLICATION, SELECTION, AND INSTALLTION OF EXPANSION VESSELS
AND ANCILLARY EQUIPMENT FOR SEALED WATER SYSTEMS
BS 5440 Part 1, when the terminal is 0.5 metres (or less) below
plastic guttering or 1 metre (or less) below painted eaves.
3.5 AIR SUPPLY
The following notes are intended for general guidance only.
This appliance is a room-sealed, fan-ued 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 ows 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 oors, 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 lling of the system.
3.6.5 EXPANSION VESSEL
The appliance has an integral expansion vessel to accommodate the increased volume of water when the system is
heated. It can accept up to 8 litres of expansion from within
the system, generally this is sufcient, however if the system
has an unusually high water content, it may be necessary to
provide additional expansion capacity (see 6.18).
3.6.6 FILLING POINT
A method for initial lling of the system and replacing water lost
during servicing etc. directly from the mains supply, is provided
(see g. 8). This method of lling complies with the current Water
Supply (Water Fittings) Regulations 1999 and Water Bylaws
2000 (Scotland). If an alternative location is preferred, it should
be connected as detailed in g. 8.
3.6.7 LOW PRESSURE SEALED SYSTEM
An alternative method of lling 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 g. 9).
The cold feed from the make-up vessel or tank must be tted
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.
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 ue 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 specically for this purpose. An
existing compartment/cupboard may be utilised provided that
it is modied 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. Instal-
lation pipes must be tted 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
tightness 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 g. 7). 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 at roofs)
the terminal must be protected by a guard of durable material.
The guard must be tted centrally over the terminal. Refer to
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