Worcester 26CDi Xtra Installation And Servicing Instructions Download Page 11

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Fig. 9. Mains electricity connections.

Strain relief clamp

Green/yellow

Brown

Blue

Green/yellow

Blue

230V

ST12

N Ns

Fig. 10. Wiring diagram.

Fan

Overheat

cut-off

device

Flame sense
electrode

Fan electrical connections
Black

White

Red

Air pressure
switch

Spark
electrode

Spark

transformer

Mains in

Link

Control Board

DHW
sensor

Flow
switch

ST16

2 blue

2 orange

2 brown

white

red

black

brown

blue

brown

2 violet

white

2 red

2 yellow

pink

ST12

ST8

ST15 ST1

Pump

CH sensor

Gas valve

Reg

Main

2 green

Summary of Contents for 26CDi Xtra

Page 1: ... Hot Water and Central Heating Minimum 6 7 kW Maximum 26 0 kW In Condensing Mode THIS APPLIANCE IS FOR USE ON SEALED PRIMARY SYSTEMS ONLY IMPORTANT THESEINSTRUCTIONSAPPLYINGREATBRITAINANDIRELANDONLY THESE INSTRUCTIONS ARE TO BE LEFT WITH THE USER OR AT THE GAS METER This appliance must be installed by a competent person in accordance with the Gas Safety Installation and Use Regulations 1998 CE Thi...

Page 2: ...ing boiler When in use the boiler will operate at high efficiency emitting a white plume of condensation from the flue terminal A condensate drain point is provided on the appliance 1 6 The advice and instructions given in this document covers as far as possible the foreseeable situations which may arise Contact Worcester Heat Systems for advice on specific installations 2 1 This appliance is not ...

Page 3: ... to prevent condensate dripping from the flue terminal NB A white plume of condensate will be emitted from the flue terminal when the appliance is operating Refer to Section 4 Siting the appliance A terminal guard Type K2 GC 393 553 is available from Tower Flue Components Vale Rise Tonbridge TN9 1TB Do not allow the flue terminal fitted to the outside wall to become obstructed or damaged A kit for...

Page 4: ...ximum output The output of the appliance is then automatically adjusted to maintain the temperature of the system The output can reduce down to a minimum of 6 7 kW If the system no longer requires even the minimum output to maintain the desired room temperature the burner will extinguish The fan will continue to run for a short period to dissipate the residual heat from the appliance The appliance...

Page 5: ...ing width 450mm 17 7 inches Casing depth 360mm 14 2 inches Weight including water 50 kg Installation weight 47 kg Pakaged weight 53 kg Primary water capacity 2 0 litres 0 45 galls Maximum cold supply pressure 10 Bar 150 psi Minimum cold supply pressure working for max hot water flow 1 2 bar Minimum cold supply pressure working to operate appliance 0 7 bar Maximum central heating flow temperature N...

Page 6: ...75mm of the casing See BS476 4 4 9 The distance between the inner face of a cupboard door and the cabinet front should not be less than 75mm 4 10 Always consider the possible need to disconnect the pipes from the appliance after installation 4 11 LPG Installation The appliance shall not be installed in a room or internal space below ground level when it is intended for use with LPG This does not p...

Page 7: ...n closed A B C D E F G 91 A B C D and E 61 110 G F G 85 A B C D E G F View on underside of appliance showing connections Rear of appliance A CH Flow 62 5 B DHW Out 127 5 C Mains Cold Water In 192 5 D Gas Inlet 257 5 E CH Return 322 5 F Valve Discharge Relief 382 5 G Condensate Drain 398 195 ...

Page 8: ...ncreased to those given below Note The clearances at the front are for a removable panel e g a door 6 3 If the appliance is to be fitted in a cupboard or compartment with less clearance than those in the table above minimum clearances are given in Section 4 Siting the appliance then permanent air vents for cooling are required One at high level and one at low level either direct to outside air or ...

Page 9: ...ngress and fill until the required pressure is reached Turn the grey knob clockwise to stop filling and remove the filling key by lining up the bayonet end of the key with the cut outs in the filling loop housing and withdrawing the key N B The key must always be removed from the filling loop housing after the system has been filled to prevent accidental filling and to comply with Byelaw 14 of the...

Page 10: ...limited by the control circuit there is normally no need for water treatment to prevent scale accumulation In exceptional circumstances a device to prevent scale formation can be fitted Installation of a scale inhibitor assembly should be in accordance with the requirements of the local Water Company An isolating valve should be fitted to allow servicing The water hardness can be determined using ...

Page 11: ... cut off device Flame sense electrode Fan electrical connections Black 1 White 4 Red 3 Air pressure switch Spark electrode Spark transformer Mains in Link Control Board DHW sensor Flow switch ST16 2 blue 2 orange 2 brown white red black brown blue blue brown 2 violet white 2 red 2 yellow 2 pink ST12 ST8 ST15 ST1 Pump CH sensor Gas valve Reg Main 1 3 1 Main 2 green ...

Page 12: ...ectronics Electronics Electronics Electronics Inputs Outputs Spark Indicators Settings Regulator valve CH demand indicator Red Spark electrodes DHW demand indicator Red Flame detect indicator Red Main valve Main valve Flow switch CH sensor DHW sensor Air pressure switch Flame sense Overheat cut off 24V programmer Reset button Gas valve mode switch CH pressure adjust pot CH Control knob DHW control...

Page 13: ...and programmer connections Fig 13 230 V programmer connections NS LS ST8 ST8 ST8 Remove link Neutral Live Switched live Neutral Neutral S w i t c h e d l i v e L i v e Live S w i t c h e d l i v e LR Spare NS LS LR Spare Spare Motor Neutral Live Switched live NS LS LR Motor ...

Page 14: ...pliance is in accordance with the instructions given in Sections 4 and 5 Also refer to fig 2 Hold the wall plate on the wall onto which the appliance is to be fitted Check the wall plate is horizontal See fig 16 Ensure the plastic cover over the valves and O rings is left in place The cover will protect the valves and O rings against ingress of dirt and dust Mark the position of the fixing holes T...

Page 15: ...it into the cold water inlet on the diverter valve See fig 18 15 Fig 16 Marking the Flue Positions for all Flue Options and Fixing the Wall Mounting Plate 21 2 Incline Side flue installation Draw a line inclining towards the appliance by 21 2 in the appropriate direction Mark horizontal line along here NOTE 21 2 is equivalent to 44mm per metre length Corner Side flue installation This is the side ...

Page 16: ... household drainage system and have an internal termination If this is not practical discharge into an outside gully or soak away is acceptable The condensate discharge pipe should have a fall of 21 2 44mm per metre length The minimum pipe diameter for internal runs is 15mm and 32mm for external runs Any external runs should also be insulated to prevent it from freezing It is not necessary to prov...

Page 17: ...l through the holes in the flue terminal into the air duct with the drill provided Fix the flue terminal temporary with the screws provided NB When assembled correctly the flue duct will extend 44mm beyond the air duct See fig 23 g Undo the screws and ease the air duct clear of the flue terminal Apply a bead of silicone sealant provided around the groove in the air duct Reassemble the air duct int...

Page 18: ...Flue assembly is used refer to fig 17 for the hole in the wall diameter Measure and cut the ducts as previously described in Section 10 4 and 10 5 Assemble the air and flue ducts to the flue terminal and flue turret as previously described See Section 10 4 Fit the rubber sealing gasket to the flue terminal Centralise the gasket and tighten the clamping ring See fig 25 Pass the assembly through the...

Page 19: ...frost thermostat if fitted or leave operating continuously with the room thermostat set at 6 C Summary The appliance is dispatched with the controls set to provide a maximum output for the domestic hot water and central heating of Non condensing mode 24 0kw 81 900 Btu h Condensing mode 26 0kw 88 760 But h The appliance modulates automatically to satisfy lower heat loads Domestic Hot Water System C...

Page 20: ...itial system design pressure is obtained up to a maximum of 1 5 bar Intial system design pressure bar Expansion vessel charge pressure 0 3 bar Note 1 bar is equivalent to 10 2 meters 33 5 ft of water N B The key must always be removed from the filling loop housing after the system has been filled to comply with Bylaw 14 of the Water Byelaws Scheme and to prevent accidential filling Store the key i...

Page 21: ...ner setting pressure should be 11 7 mbar for natural gas and 35 5 mbar for propane Set the gas valve mode switch to the normal position Turn both the central heating control knob and the domestic water control knob to their maximum position i e fully clockwise Turn off the hot water tap The burner pressure will drop to minimum setting and will ramp up to maximum central heating setting The burner ...

Page 22: ...ion 11 1 Domestic Hot Water and Central Heating Set the gas valve mode switch to the normal position Turn on the electricity supply to the appliance and open the gas supply cock at the appliance Set the Operating Switch and Programmer to HEATING and WATER If a programmer is fitted set the domestic hot water to Continuous or 24Hrs and the central heating to ON The burner will light and heat will pa...

Page 23: ...y at the gas service cock on the appliance before servicing After completing the service always test for gas soundness as indicated in BS 6891 13 3 DISMANTLE THE APPLIANCE To carry out a full and comprehensive service of the appliance remove the following parts to gain access to the components which need to be checked or serviced a Cabinet Front Panel Remove by lifting off the supports b Inner Cas...

Page 24: ... sealing washer Unscrew the front burner fixing screw Lift the burner and ease the union nut through the inner casing sealing grommet Remove the burner assembly clear of the inner casing Ensure the flame sensing lead passes through the base of the inner casing See fig 32 and 36 24 Fig 32 Appliance Components and Fixings upper assembly Fan outlet spigot Red sensing tube Clear sensing tube Detail of...

Page 25: ...l will also require to be hinged down as described in Section 13 3 c IMPORTANT The following components are secured to the appliance with clips wire clips screws union fittings or O ring seals to ensure the joints are sound See figs 32 and 37 Automatic air vent Gas to water heat exchanger Circulating pump Water to water heat exchanger Water diverting valve Pressure relief valve Pressure gauge Gas ...

Page 26: ... inner casing cover fan flue hood assembly overheat thermostat central heating sensor and burner as described in Section 13 3 b e f g and h and Section 14 3 4 and 12 Slacken the two screws and remove the two side retaining brackets Lift the heat exchanger clear of the casing Take care the rear insulation panel does not drop forwards onto the burner Retain the screws and brackets discard the heat e...

Page 27: ...et the burner pressure See fig 29 After a new gas valve has been fitted the burner pressures must be set Follow the procedure described in Section 11 3 Appliance Operation Turn both the central heating control knob and the domestic water control knob to their maximum position i e fully clockwise The maximum domestic hot water burner pressure must be set first because it affects the other pressures...

Page 28: ...anel down into the Servicing Position as described in Section 13 3 c Unscrew the two pump union nuts and the pipe to the expansion vessel Ease the pump from the pipe work Support the pump and remove the electrical cover Disconnect the electrical wires taking note of their positions Remove the pump from the appliance Unscrew the expansion vessel brass connection from the pump Discard the pump retai...

Page 29: ...Drain the central heating and domestic hot water circuits as described in Sections 14 2 a and b Hinge down the facia panel into the Servicing Position as described in Section 13 3 c Remove the bottom panel as described in Section 13 3 d Remove the filling loop as described in Section 14 3 16 Unscrew the left hand union connection to the diverter valve Remove the screw and clamp from the right hand...

Page 30: ...8 37 39 and 40 Check that the electric supply to the appliance is turned off Drain the central heating and domestic circuits as described in Sections 14 2 a and b Hinge down the facia panel into the servicing position as described in Section 13 3 c Follow the proceedures as described in Section 14 3 19 and remove the water divering valve from the appliance Remove the water filter from the cold wat...

Page 31: ...the board off the remainder of the mounting posts until it is free Unplug the transformer from rear of the board Discard the control board retain the transformer Plug in the transformer to the replacement control board The transformer will fit in one direction only Locate the replacement control board over the four mounting posts and push back squarely until the plastic catch on the end of each po...

Page 32: ...ll off the two clips securing the flow and return pipes to the heat exchanger located under the inner casing Ease the O ring connections just clear of the fittings Warning A quantity of primary water will remain in the heat exchanger and pipework iii Unscrew the two union lock nuts securing the flow and return connections to the inner casing iv Disconnect the plastic drain pipe to the condensate t...

Page 33: ...appliance is turned off Drain the central heating and domestic hot water circuits as described in Sections 14 2 a and b Hinge down the facia panel into the Servicing Position as described in Section 13 3 c Pull out the retaining clip and ease the capillary tube out of the CH return manifold The pressure gauge is secured into the facia with two plastic clips Ease the clips apart and remove the pres...

Page 34: ...RA ref BV 066 0188 0 1 87472012480 65 299 497 Fan Assembly RSF 1 8716121192 0 66 Air Pressure Sensing Probe RSF WHS Drg 010548 1 87161411900 129 E04 598 Differential Air Pressure Switch RSF 1 87161567440 60 375 696 Thermister Sensor Elmwood 2 8716142 3840 62 173 015 Overheat Thermostat Elmwood ref 2455 R 98 789 1 8716142 3030 133 299 354 Combustion Chamber Insulation Pack WHS 1 7716192204 0 134 29...

Page 35: ...35 96 NG OR LPG NG OR LPG 109 201 ...

Page 36: ...l On Over tempera ture shut down if flow temperature 5 C above set value Two minute minimum burner pressure then ramp up pressure over next one minute Modulate gas to maintain flow temperature set by control knob DEMAND END Pump continue four minutes Fan continue fifteen seconds CENTRAL HEATING FUNCTION AND AND AND CH light on Pump on Fan high 3 seconds then low ignition sequence Burner light on P...

Page 37: ...r shut down if primary temperature 94 C until 84 C Four second ramp to max gas pressure Modulate gas to maintain delivered water temperature to value set by control knob DEMAND END Fan continue fifteen seconds Possible overrun condition within next four minutes See next section DOMESTIC HOT WATER FUNCTION HW light on Pump on Fan high 3 seconds then low ignition sequence Burner light on Modulate ga...

Page 38: ...primary drops to 80 C If primary temperature still increases above 90 C Run pump for two seconds OVERRUN FUNCTION AND Above 9 C Commence normal central heating mode until temperature reaches 30 C 5 C to 9 C Below 5 C No demand and primary temperature below 8 C Internal Autofrostat demand Wait in normal off state for 30 minutes Run pump for four minutes Monitor central heating sensor Return to norm...

Page 39: ...y flashing they can also be used to help provide fault diagnostics Therefore with individual or groups of lights being permanently off on or flashing every normal fault can be identified To use the fault finding system select a box below which represents the light situation during your fault Then refer to the appropriate following section This fault finding system assumes that the appliance has be...

Page 40: ...y to boiler Replace control board Section 14 3 23 FAIL POINT A No No Yes Yes Yes No Replace fuse This will be caused by fuse fatigue or by the board Has fuse F2 blown Replace control board Section 14 3 23 Remove control board from facia See Section 14 3 23 and separate transformer from board Measure resistance across the two pairs of adjacent pins on the transformer Is any pair above 100 ohms Repl...

Page 41: ...grammer Yes Yes Red diode is damaged Replace control board Section 14 3 23 Replace control board Section 14 3 23 With a hot water tap fully open does the boiler ignite and appear to run normally in hot water mode Remove multiway connector from board position ST16 With tap still open is there continuity across contacts 19 and 20 2 pink wires Remove the black cover from the microswitch assembly With...

Page 42: ...l air vented Rectify fault FAIL POINT G Primary Overheat No Repair or replace pump Section 14 3 14 No No Reset the controls and restart the boiler Does the pump run Yes Remove inner casing cover and inspect the primary sensor left of heat exchanger Is it correctly fixed to pipe Yes Replace control board Section 14 3 23 Note A wet board could cause this fault Yes Turn to normal position No Re fix s...

Page 43: ...Remove inner cover Reset and restart the boiler Does a spark occur across the electrodes Turn off boiler Remove the multiway connector from board position ST16 Test resistance across contacts 7 and 8 brown wires and 9 and 10 violet wires Are both readins below 100 ohms Replace control board Section 14 3 23 Repair or replace flame sensor Section 14 3 10 or wiring Replace gas valve Section 14 3 11 A...

Page 44: ...trol board Section 14 3 23 Check or replace CH sensor Section 14 3 12 Is there continuity from contacts 17 and 18 to DHW sensor Check or replace DHW sensor Section 14 3 13 Is there continuity from contacts 12 and 13 to CH sensor Repair or replace harness Repair or replace harness Is the multiway connector at board position ST16 pushed fully home on to the board Push fully home FAIL POINT I Sensor ...

Page 45: ...iler Is there continuity between C and NO terminal where green wires were fitted when the fan runs Pressure switch has not closed Are the silicon tubes in good condition and free of condensation Replace air pressure switch Section 14 3 2 Note In the unlikely event of this not solving the problem inspect the pressure pick up Venturi in the fan Inspect condensate drain Is it free from any restrictio...

Page 46: ... be off or poorly fixed to pipe Repair or replace sensor Section 14 3 13 Water temperature very low low gas pressure with all knobs set to maximum Remove multiway connector from board position ST16 Is the resistance across contacts 1 and 2 blue wires below 60 ohms Remove blue top connector from gas valve Is there continuity along blue wires to multiway connector Is the gas set to correct pressure ...

Page 47: ...47 ...

Page 48: ...ed in the interests of continued improvement All goods sold are subject to our official Conditions of Sale a copy of which may be obtained on application PUBLICATION 8 716 145 159 Issue D 05 99 Bosch Group Worcester Heat Systems Limited Cotswold Way Warndon Worcester WR4 9SW Telephone 01905 754624 Fax 01905 754619 Technical Helpline 0990 266241 ...

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