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16

4.6.5 SAFETY VALVE (fig. 16)

Connect the safety valve connection pipe to the safety valve 

outlet. Connect a discharge pipe to the other end of the safety 

valve connection pipe and tighten. The discharge pipe must 

have a continuous fall away from the appliance to outside and 

allow any water to drain away thereby eliminating the possibil-

ity of freezing. The discharge pipe must terminate in a position 

where any water – possibly boiling – discharges safely without 

causing damage or injury, but is still visible.

4.6.6 CONDENSE PIPE

During normal operation the boiler produces condense which 

is collected in a trap located in the lower part of the boiler. A 

flexible pipe (condense outlet pipe) is connected to the outlet 

of the trap. The flexible pipe must be connected to a plastic 

waste pipe only. The plastic waste pipe must have a minimum 

of a 3º fall towards the drain. Any external run of pipe should 

be insulated to prevent the risk of freezing.  

4.6.7 CONNECTING THE CONDENSATE OUTLET

Connect the flexible condense outlet pipe supplied in the carton 

to the condense trap inside the boiler, care should be taken to 

ensure that the trap connections are not disturbed.

Connect a suitable plastic (not copper) pipe (no less than 20mm 

diameter) to the outlet pipe and ensure it discharges in accord-

ance with building regulations or other rules in force.

4.7 ELECTRICAL CONNECTIONS

The boiler is supplied with a 2-metre fly-lead. This lead can 

be used for connection to the electrical supply. Connect the 

fly-lead to a fused plug or fused isolator in the following way:

•  brown wire to LIVE supply

•  blue wire to NEUTRAL supply

•  green/yellow to EARTH connection.

Insert the supplied 3-AMP fuse into the fused isolator or fused plug. 

Should the fly-lead be unsuitable, refer to 4.7.3 for details on 

how to connect the electrical supply directly to the boiler. 

The  electrical  supply  must  be  as  specified  in  section  3/3A. 

A  qualified  electrician  should  connect  the  appliance  to  the 

electrical supply. If controls - external to the appliance - are 

required, a competent person must undertake the design of 

any external electrical circuits, please refer to section 8 for 

detailed instructions. ANY EXTERNAL CONTROL OR WIRING 

MUST BE SERVED FROM THE SAME ISOLATOR AS THAT 

OF THE APPLIANCE. The supply cable from the isolator to the 

appliance must be 3-core flexible sized 0.75mm to BS 6500 or 

equivalent. Wiring to the appliance must be rated for operation 

in contact with surfaces up to 90 ºC.

4.7.1 CASING REMOVAL (fig. 17)

To gain internal access to the appliance you must first remove 

the casing, proceed as outlined below:

•  locate and unscrew the 2-screws (

A

) that secure the outer 

casing to the appliance 

•  lift the casing upward to disengage it from the top locating 

hooks and then remove

•  store the casing and screws safely until required. Re-fit in 

the reverse order

•  gently lower the control fascia until it rests.

Fig. 16

4.7.2 APPLIANCE TERMINAL BLOCK

The appliance terminal block is located on the rear of the con-

trol fascia. Remove the casing as described in 4.7.1. Gently 

pull the control panel forwards and down. Locate the terminal 

block cover (fig. 18).

NOTE

The appliance comes with a factory fitted connector plug to 

allow

Quick and easy connection to the Vokera time clock. If it is an-

ticipated that external controls will be required please refer to 

the wiring diagrams in section 8 for more detailed information.

4.7.3 CONNECTING THE MAINS (230V) INPUT 

Unhook and remove the terminal block cover (230V). Pass the 

cable through the cable anchorage point. Connect the supply 

cable wires (LIVE, NEUTRAL, & EARTH) to their corresponding 

terminals (L, N, & E) on the appliance – high voltage – terminal 

block. When connecting the EARTH wire, ensure that it’s left 

slightly longer that the others, this will prevent strain on the 

EARTH wire should the cable become taut. Do not remove the 

link wire unless additional external controls are to be fitted (see 

section 8). The securing screw on the cable anchorage should 

now be tightened. This must be done before the terminal block 

cover is re-fitted in its position.  

NOTE

It is the installer’s responsibility to ensure that the appliance is 

properly Earthed. Vokèra Ltd. cannot be held responsible for any 

damages or injuries caused as a result of incorrect Earth wiring.

Fig. 17 

A

Fig. 18

Hot water 

outlet

Cold water inlet 

stopcock/filling 

valve

Gas 

cock

C/H flow 

valve

C/H return 

valve

Safety 

valve outlet

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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