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22

6.20.3 VALVE ACTUATOR (fig. 35)

Carry out component removal procedure as described in 6.4.

Remove the locking pin (

G3

) that secures the actuator (

H2

) to 

the heating manifold. Disconnect the electrical plug from the 

actuator. Replace in the reverse order.

6.20.4 DHW THERMISTOR (fig. 24)

Carry out component removal procedure as described in 6.4.

Locate and remove the thermistor locking pin (

I2

). Gently ease 

the thermistor assembly (

J2

) from the hydraulic manifold. Re

-

place in the reverse order.

6.20.5 DIVERTOR VALVE ASSEMBLY (fig. 35)

Carry out component removal procedure as described in 6.4. 

Remove the valve ac

tuator as described in 6.20.3. Locate and 

remove the locking pin (

G2

) that secures the valve housing 

cover to the hydraulic manifold. Gently prise the valve as-

sembly from the manifold (

K2

). R

eplace in the reverse order 

ensuring that the seating assembly is inserted properly. Ensure 

all seals are in good condition, taking care to ensure they are 

replaced correctly.

G2

Fig. 35

6.20.2 DHW FLOW SWITCH (fig. 34)

Carry out component removal procedure as described in 6.4.

Remove the locking pin (

D2

). Disconnect and remove the cold 

water inlet pipe from the DHW flow switch & DHW heat ex

-

changer. Disconnect the wiring to the DHW flow switch. 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 switch, taking care not 

to lose the float contained within the housing.

Replace in the reverse order ensuring that the housing is firmly 

inserted onto its seating. Ensure all seals are in good condition, 

taking care to ensure they are replaced correctly.

Fig. 34

H2

K2

B2

C2

D2

E2

F2

Y1

Fig. 33

Z1

A2

6.20 FLUE COLLECTOR REMOVAL (fig. 33)

Carry out component removal procedure as described in 6.4. 

Remove the air chamber front cover. Remove the heat exchang

-

er as per 6.16. Locate and remove the screw (

Y1

) that secures 

the flue gas analysis test point cover (

Z1

). Disconnect the flues 

thermistor wiring connections. Locate and remove the 4 screws 

(

A2

).  Locate and remove the 2 screws (

A3

).  Gently ease the 

condensate collector (

A4

) out off its location. Gently ease the 

flue collector out off its location. Replace in the reverse order.

6.20.1 DHW FLOW RESTRICTOR (fig. 34)

Carry out the component removal procedure as described in 

6.4.

Disconnect the cold water inlet pipe at the DHW flow switch 

(

B2

). Using a small screwdriver, gently ease the flow restrictor 

(

C2

)  from  its  seating.  Replace  in  the  reverse  order.  Ensure 

all seals are in good condition, taking care to ensure they are 

replaced correctly.

A3

A4

G3

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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