background image

18

6.1  GENERAL

Once the appliance has been serviced, the benchmark Service 

Record must be completed.
For UK only: It is important that the Benchmark Service Record 

is correctly completed and handed to the user. Failure to install 

and commission the appliance to the manufacturers instructions 

will invalidate the warranty.

To ensure the continued safe and efficient operation of the ap

-

pliance, it is recommended that it is checked and serviced at 

regular intervals. To ensure correct and safe operation of the 

appliance, it is essential that any worn or failed component be 

replaced only with a 

genuine Vokèra spare part

. It should be 

remembered that although certain generic components may 

look similar, they will be specific to an individual appliance or 

product range. Use of non-genuine Vokèra spare parts could 

invalidate your warranty and may pose a potential safety haz-

ard. The frequency of servicing will depend upon the particular 

installation conditions, but in general, once per year should be 

sufficient. It is the law that any servicing work is carried out by 

competent person such as a Vokèra engineer, an approved 

service agent, British Gas, GAS SAFE registered personnel 

or  other  suitably  qualified  personnel. The  following  instruc

-

tions apply to the appliance and its controls, but it should be 

remembered that the central heating and the domestic hot 

water systems would also require attention from time to time.

6.2 ROUTINE ANNUAL SERVICING

•  Check the operation of the appliance and ensure it functions 

as described in section 7.

•  Compare the performance of the appliance with its design 

specification. The cause of any noticeable deterioration should 

be identified and rectified without delay.

•  Thoroughly  inspect  the  appliance  for  signs  of  damage  or 

deterioration  especially  the  flue  system  and  the  electrical 

(up to the maximum of 1.5 BAR total). 

N.B.

 The safety valve 

is set to lift at 3 BAR/30 metres/45 psig. To lower the system 

pressure to the required value, drain off some water from the 

appliance drain valve until the required figure registers on the 

pressure gauge (see fig. 1).

5.11 REGULATING THE CENTRAL HEATING 

SYSTEM

Fully open all radiator and circuit valves and run the appliance 

for both heating and hot water until heated water is circulating. 

If conditions are warm remove any thermostatic heads. Adjust 

radiator return valves and any branch circuit return valves 

until the individual return temperatures are correct and are 

approximately equal.

5.11.1 REGULATING THE DHW FLOW-RATE

The appliance is fitted with a flow rate restrictor that limits the 

maximum flow rate that can be drawn through the appliance.

The restrictor eliminates the need to manually adjust the DHW 

flow rate. However if it is felt necessary to further increase or 

decrease the available flow rate, spare restrictors are available 

to Vokèra spare parts.

The spare flow rate restrictors can be fitted to either increase 

or decrease the maximum flow rate. 

5.11.2 FLOW-RATE RESTRICTOR

The boiler is supplied with the following flow restrictor.

Excel 25:

 8 - litres flow restrictor

Excel 29: 

10 - litres 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 SECURED.

•  ENSURE ALL PIPE WORK IS RE-CHECKED FOR TIGHT

-

NESS.

•  RE-FIT APPLIANCE CASING.

•  COMPLETE BENCHMARK CHECKLIST.

FOR UK ONLY

Complete details of the boiler, controls, installation and com-

missioning in the Benchmark checklist at the back of this 

book. It is important that the Benchmark checklist is correctly 

completed and handed to the user. Failure to install and com-

mission the appliance to the manufacturers instructions will 

invalidate the warranty.

5.13 INSTRUCTING THE USER

Hand over all documentation supplied with this appliance – 

including these instructions – and explain the importance of 

keeping them in a safe place.

Explain to the user how to isolate the appliance from the gas, 

water and electricity supplies and the locations of all drain 

points. Show the user how to operate the appliance and any 

associated controls correctly.

Show the user the location of the filling valve and how to top-

up the system pressure correctly and show the location of all 

manual air release points.

Explain to the user how to turn off the appliance for both long 

and short periods and advise on the necessary precautions to 

prevent frost damage.

Explain to the user that for continued safe and efficient operation, 

the appliance must be serviced annually by a competent person.

IMPORTANT

To validate the appliance warranty, it’s necessary to register 

the appliance details with us. The warranty can be registered 

in several ways:

•  by completing the warranty registration card and posting to 

us using the envelope supplied

•  online at: vokera.co.uk

•  for UK residents by calling: 0870 607 0281

•  for ROI residents by calling: 056 6655057.

SECTION 6 - SERVICING INSTRUCTIONS

apparatus.

•  Check and adjust – if necessary – all burner pressure settings 

(see 7.4).

•  Check and adjust – if necessary – the system design pressure 

(see 5.10).

•  Carry out an analysis of the flue gases (see 7.5), and visually 

check the condition of the entire flue assembly.

•  Compare the results with the appliance design specification. 

Any deterioration in performance must be identified and recti

-

fied without delay.

•  Check that the main heat exchanger are clean and free from 

any debris or obstruction.

•  Check and clean – if necessary – the condense trap to ensure 

correct operation.

The flame side of the burner is made of state-of-the-art material. 

Being fragile: 

-  be particularly careful when handling, mounting or disman-

tling the bur ner and adjacent components (e.g. electrodes, 

insulation panelling etc.) 

-  avoid direct contact with any cleaning appliance (e.g. brushes, 

aspira tors, blowers, etc.). 

This component does not need any maintenance, please do 

not remove it from its housing, save where the O-ring may have 

to be replaced. 

The manufacturer declines all responsibility in cases of damages 

due to failing to observe the above.

6.3  REPLACEMENT OF COMPONENTS

Although it is anticipated that this appliance will give years of 

reliable, trouble free service, the life span of components will be 

determined by factors such as operating conditions and usage. 

Should the appliance develop a fault, the fault finding section 

will assist in determining which component is malfunctioning.

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...

Reviews: