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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 fitted);

-  any external thermostats and their functions;

-  the appliance controls.

2.2 APPLIANCE CONTROLS (see fig. 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 fitted).

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 flows from your hot water taps.  The temperature range is 

adjustable between 40

o

C and 80

o

C for the central heating, and 

between 37

o

C and 60

o

C 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 

flame is present and the burner is ON.

When the 

fault indicator (Red) is lit

 it indicates that the appliance 

has identified 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 fitted)

 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 pro-

grammer, 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 satisfied, 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 TEMPERA-

TURE

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 sufficiently hot enough, it may be necessary to reduce the 

flow 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 

(fig. 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  filling  valve  connections  (usually  beneath  the 

boiler, see fig. 2).

-  Attach the filling loop to both connections.

-  Open the filling valve slowly until you hear water entering the 

system.

-  Close the filling valve when the pressure gauge (on the boiler) 

reads between 1 and 1.5 BAR (see fig. 1).

-  Remove the filling 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 fig. 1).

IMPORTANT

If the appliance requires to be reset frequently, it may be indica-

tive 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

flow/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 advis-

able 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 scour-

ers or abrasive 

cleaners.

Summary of Contents for Excel 25

Page 1: ...S TO BE RETAINED BY USER Vok ra 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 ef...

Page 2: ...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...

Page 3: ...el 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 efficiency Please therefore take some ti...

Page 4: ...et 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 bo...

Page 5: ...may be necessary to reduce the flow 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 a...

Page 6: ...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 VOK RA Advice for homeowners Please c...

Page 7: ...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...

Page 8: ...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...

Page 9: ...ume 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 o...

Page 10: ...ain 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 flue H From internal external corner 25 mm 60mm for 80 125...

Page 11: ...n vessel to accom modate 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 sufficient however if the system has...

Page 12: ...is to be fitted on a wall of combustible material There is no requirement to protect the wall 3 9 TIMBER FRAMED BUILDINGS If the appliance is to be fitted in a timber framed building it shouldbefitte...

Page 13: ...W 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 an...

Page 14: ...plane see2 9 Areductionmustalsobemadetothemaximumlength see table below when additional bends are used Reduction for additional bends Bend Reduction in maximum flue length for each bend 45 bend 1 0 me...

Page 15: ...e installation of the 80 125mm concentric flue system please refer to the instructions supplied The vertical flue terminal can be connected directly to the ap pliance flue outlet Alternatively an exte...

Page 16: ...ir 2000mm 0225840 45 bend pair N A 0225845 90 bend pair N A 0225850 Twin bracket 5 N A 0225855 Single bracket 5 N A MOUNTING THE BOILER The fixing holes for the wall mounting bracket should now be dri...

Page 17: ...wards the appliance 17mm per 1000mm Fig 13c Fig 14 4 6 CONNECTING THE GAS AND WATER The appliance is supplied with an accessory pack that includes service valves Theservicevalvesareforwelding Theacces...

Page 18: ...circuits please refer to section 8 for detailed instructions ANYEXTERNALCONTROLOR WIRING MUST BE SERVED FROM THE SAME ISOLATOR AS THAT OF THE APPLIANCE The supply cable from the isolator to the appli...

Page 19: ...d properly and in ac cordance with the instructions ensure all appliance service valves are open 5 6 INITIAL LIGHTING Ensure the electrical supply to the appliance is switched on Ensure any external c...

Page 20: ...tres flow restrictor 5 12 FINAL CHECKS ENSURE ALL TEST NIPPLES ON THE APPLIANCE GAS VALVE ARE TIGHT AND CHECKED FOR TIGHTNESS ENSURE THE APPLIANCE FLUE SYSTEM IS FITTED CORRECTLY AND IS PROPERLY SECUR...

Page 21: ...ved from the appliance Replace carefully in the reverse order 6 6 SAFETY VALVE fig 22 Carry out component removal procedure as described in 6 4 Disconnect the outlet pipe G from the safety valve remov...

Page 22: ...omponent removal procedure as described in 6 4 Remove the air chamber front cover Disconnect the electrode leads and ancillary wiring from their respective connectors Re move the retaining screws V fo...

Page 23: ...ibed in 6 4 Remove the locking pin Q1 that secures the cover R1 to the hydraulic manifold Using a hooked piece of wire carefully withdraw the by pass cartridge S1 and or DHW non return cartridge T1 En...

Page 24: ...onnectthewiringtotheDHWflowswitch Slacken and unscrew the inlet connection Unscrew the nut E2 Lift the DHW flow switch housing from its seating If necessary remove the locking pin F2 from the DHW flow...

Page 25: ...sed for more that 20 minutes 7 2 3 HEATING MODE With the selector switch in the heating hot water position and any additional controls time clock programmer room thermostat etc calling for heat the ap...

Page 26: ...ut the component removal procedure as described in 6 4 You must ensure that the boiler is completely drained of water Using a suitable pressure gauge remove dust cap on expansion vessel and check the...

Page 27: ...letion of any task that required the disconnection and re connection of any electrical wiring or component these checks must be repeated 7 8 FAULT FINDING Before attempting any faultfinding the electr...

Page 28: ...c information on the suitability of a particular control Further guidance on the recom mended practice for the installation of external controls can be found in CHeSS HC5 HC6 www energyefficiency gov...

Page 29: ...oiler lock out CN1 CN15 Connectors CN5 Room thermostat 24 Vdc S W CO2 function button F S 1 Flame sensor F1 Fuse 3 15A T F External fuse 3 15A F M3 Terminal strip for electrical connection hight power...

Page 30: ...yellow led blinking gas valve maximun setting press twice burner running at maximum DHW yellow led blinking red led fixed gas valve minimum setting press three time burner running at minimum yellow l...

Page 31: ...3 However if the CO2 reading is incorrect the minimum gas pressure must be adjusted as follows locate the minimum adjustment screw fig 37 using a suit able screwdriver remove the protection plug using...

Page 32: ......

Page 33: ......

Page 34: ...to stabilise YES Is CO less than 350ppm AND CO CO2 ratio less than 0 004 NO Boiler is operating satisfactorily No further actions required Ensure test points are capped boiler case is correctly repla...

Page 35: ......

Page 36: ...s vokera co uk www vokera co uk www vokera ie Sales General Enquires T 0844 391 0999 F 0844 391 0998 Vok ra Ireland West Court Callan Co Kilkenny T 056 7755057 F 056 7755060 Vok ra Limited reserve the...

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