Worcester 28Si Installation And Servicing Instructions Download

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WALL MOUNTED COMBINATION BOILERS FOR CENTRAL HEATING

AND MAINS FED DOMESTIC HOT WATER

INSTALLATION AND

SERVICING INSTRUCTIONS

This appliance is for use with Natural Gas or LPG (Cat II 2H3P).

25Si GC NUMBER 47 311 49 (N.G.)

CG NUMBER 47 311 50 (L.P.G.)

28Si GC NUMBER 47 311 51 (N.G.)

CG NUMBER 47 311 52 (L.P.G.)

APPLIANCE OUTPUTS

Domestic

Central Heating

Hot Water

28 25 28

Minimum 8.5 kW 8.5kw 8.5 kW 8.5kw
Maximum 25.0kW 28.0kw 25.0kW 28.0kw

IMPORTANT: THESE INSTRUCTIONS APPLY IN THE UK ONLY

AND MUST BE LEFT WITH THE USER OR AT THE GAS METER

Read the instructions before starting work - they have been written to make

the installation easier and prevent hold-ups.

Summary of Contents for 28Si

Page 1: ...MBER 47 311 50 L P G 28Si GC NUMBER 47 311 51 N G CG NUMBER 47 311 52 L P G APPLIANCE OUTPUTS Domestic Central Heating Hot Water 25 28 25 28 Minimum 8 5 kW 8 5kw 8 5 kW 8 5kw Maximum 25 0kW 28 0kw 25 0kW 28 0kw IMPORTANT THESE INSTRUCTIONS APPLY IN THE UK ONLY AND MUST BE LEFT WITH THE USER OR AT THE GAS METER Read the instructions before starting work they have been written to make the installati...

Page 2: ...from a householder who will be advised that he or she must call back the installer who has not fulfilled his obligations to record the information required by the initiative It is important that The services and the system are properly flushed as specified The User is clearly instructed on the correct operation of the appliance The benefits of regular servicing are explained to maintain the effici...

Page 3: ...o cold water main can be prevented This can result in a pressure build up that may cause damage to the boiler and household devices such as showers washing machines etc In these cases we recommend that a mini expansion vessel be fitted adjacent to the boiler in the cold water pipe 2 10 Operation Central Heating A demand for heat will ignite the burner It will operate at minimum pressure for 2 minu...

Page 4: ...ESTIC WATER FLOW COMPRESSION 15mm GAS INLET Rp 3 4 RELIEF VALVE DISCHARGE PUSH FIT 15mm CASING HEIGHT 800mm CASING WIDTH 440mm CASING DEPTH 360mm WEIGHT LIFT 42 3kg WEIGHT UNPACKED 45 8kg WEIGHT PACKAGED 52kg Table 4 NOMINAL BOILER RATINGS 10 Minutes After Lighting BOILER ADJUSTED FOR G20 Natural Gas OUTPUT INPUT Net GAS RATE kW kW m bar m3 h 8 5 10 5 0 7 1 12 28 0 31 1 14 1 3 38 BOILER ADJUSTED F...

Page 5: ...AXIMUM FLOW bar 1 1 1 3 MINIMUM MAINS INLET PRESSURE WORKING FOR OPERATION bar 0 5 0 5 DOMESTIC HOT WATER TEMPERATURE RANGE C 40 62 40 62 MAXIMUM CENTRAL HEATING FLOW TEMPERATURE C 82 nom 82 nom MAXIMUM CENTRAL HEATING SYSTEM SET PRESSURE bar 2 5 2 5 MINIMUM CENTRAL HEATING SYSTEM PRESSURE bar 1 1 OUTPUT TO DOMESTIC HOT WATER kw NATURAL GAS G20 8 5 25 8 5 28 0 LPG PROPANE G31 8 5 25 8 5 28 0 OUTPU...

Page 6: ...the requirements of BS6798 and BS5440 Part 2 are followed Refer to Section 2 4 The airing space must be separated from the boiler space by a perforated non combustible partition Expanded metal or rigid wire mesh is acceptable provided that the major dimension is less than 13mm The clearance between the front of the appliance and the cupboard compartment door should be not less than 75mm LPG Instal...

Page 7: ...nces given in Section 4 Siting The Appliance then permanent vents for cooling are required One at high level and one at low level either direct to outside air or to a room Both vents must pass to the same room or be on the same wall to the outside air 6 4 The minimum free areas required are 6 Air Supply 5 Flue terminal positions 7 L L K K F F G A M E J F HI D G A B C Fig 7 Siting of the flue termi...

Page 8: ...Refer to Fig 9 The system and the appliance must be properly vented Repeated venting loses water from the system which must be replaced The make up connection must be close to the appliance in the heating return pipe through an approved non return valve Refer to Fig 10 The connection to the mains water supply must have the approval of the local Water Company The integral by pass is not adjustable ...

Page 9: ...ng valve should be fitted to allow servicing The water hardness can be determined by reference to the local Water Company The appliance requires a maximum of 3 38 m3 h of natural gas G20 or 1 2 m3 h of propane G31 28Si or 2 98 m3 h of natural gas G20 or 1 25 m3 h of propane G31 25Si Refer to Table 7 A natural gas appliance must be connected to a governed meter The installation and connection of th...

Page 10: ...de Spark transformer Mains in Link Control Board CH sensor front of heat exchanger Flow switch ST16 2 blue 2 orange 2 brown brown blue blue brown 2 violet white 2 red 2 yellow 2 pink ST12 ST8 ST15 ST1 Pump Gas valve Reg Main Main 2 green brown yellow Overheat cut off device DHW sensor ...

Page 11: ...lectronics 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 knob Convert AC to low...

Page 12: ...ssembly to the wall utilising the keyhole slots on the manifold assembly and fix to the wall Refer to Fig 15 and 16 Check that the assembly is properly aligned before tightening the screws 11 6 Gas and Water Pipes Remove the gas cock and fix the appropriate fitting to connect the inlet pipe and refit Refer Fig 16 Pre plumbing is not recommended if no movement in the pipes is available If it is nec...

Page 13: ... however be strictly followed Remove all packing material from the flue components Fit the flue restrictor ring by unscrewing and removing the flue spigot from the boiler Refer to Fig 19 Restrictor Size 79mm to all Horizontal and Vertical flues upto 725mm long The standard telescopic flue assembly is suitable without cutting for flues from 425mm up to 725mm measured from the centre line of the boi...

Page 14: ...rret assembly and the terminal assembly by the same amount i e L 350 remove 75mm from each assembly Minimum side flue length 330mm accommodating a 10mm Service clearance and a 100mm wall Minimum rear flue length 330mm accommodating a 100mm wall If L is between 1175 1475mm 1 extension 1925 2225mm 2 extension 2675 2975mm 3 extension it is not necessary to cut the ducts If L is between 725 1175mm 1 e...

Page 15: ...end on the flue turret A 90 bend is equivalent to 1m of straight duct A 45 bend is equivalent to 0 5m of straight duct A maximum flue assembly of 2m is possible with 1 X 90 bend and 1m with 2 X 90 bends Measure the lengths X Y and Z Refer to Fig 26 The maximum value of X using the turret assembly only is 506mm Reduce the ducts to the appropriate length i e X 406mm cut 100mm from the air duct and 1...

Page 16: ... the socketed ends The minimum measured distance is 167mm Seal the air duct to the spigot using silicone sealant Fix the adaptor with the clamp and screw provided 11 14 Completion of the Installation Check that all the connections on the manifold have been tightened Refer to Fig 6 Remove the facia bottom panel Refer to Fig 29 Connect the mains electricity supply lead to the appliance and secure th...

Page 17: ...1 Cable clamps threaded 11 Fig 31 Programmer connection Facia Programmer connector Programmer connections Clip Programmer Pressure gauge Control board Fig 32 Mains Voltage External Controls Connections 230 V Room Thermostat Connections Ns Ls LR ST8 Ns Ls LR ST8 Remove Link Neutral Live Switched Live Neutral Live Switched Live Motor 230 V Programmer Connections 230 V room thermostat and Programmer ...

Page 18: ...ection A Schraeder type valve is fitted to the expansion vessel to allow the charge pressure to be increased if necessary Refer to Fig 34 The expansion vessel must be charged to 0 35bar less than the initial system design pressure Note 1bar 10 2m 33 5ft of water 12 3 Set the System Pressure Fill the system until the pressure gauge is at 2 5bar and check for leaks Release water from the system usin...

Page 19: ...e appropriate to the appliance and the gas Refer to Table 1 Gradually close the tap and check that the burner pressure falls Fully open the tap and check that the pressure rises Close the tap and check that the burner goes out The fan may continue running until the appliance has cooled to a pre set temperature 12 8 Central Heating Check that all the radiator valves are open Check that the system i...

Page 20: ...ng any service procedures Always test for gas soundness after the service has been completed 14 3 Component Access To service the appliance it may be necessary to remove some or all of the following parts to gain access to components which may need to be checked or replaced Cabinet Unscrew the screw at the top of the cabinet release the sides Lift up and away from the top locating pegs Facia Panel...

Page 21: ...embly Flue hood Combustion chamber flue hood fixing screws Heat exchanger Combustion chamber fixing screw Burner connection Burner Combustion chamber Primary sensor Overheat thermostat at rear Combustion products test point front cap Combustion chamber fixing screw ...

Page 22: ...t Refer to Fig 41 and 45 for an indication of the location of the various components Replace any components removed from the appliance in the reverse order using new gaskets O rings sealant heat transfer paste where necessary Always check that any electrical connections are correctly made and that all screws are tight Remove casing and cover panels and lower the facia as necessary to gain access t...

Page 23: ...the union connection beneath the burner and remove the burner from the appliance Refer to Fig 44 Do not omit the gasket when fitting the new burner 15 4 5 Combustion Chamber Insulation Remove the burner as described in 15 3 4 preceding Remove the primary heat exchanger as described in 15 4 21 following Replace the side and front pads in the combustion chamber assembly Refer to Fig 48 Replace the r...

Page 24: ...d Disconnect the relief valve drainpipe Unclip and pull out the valve Refer to Fig 51 24 Fig 48 Combustion Chamber Insulation Fig 49 Pressure Gauge head Fig 50 Pressure Gauge capillary fixing Fig 51 Relief valve drain connection Pump Relief Valve Drain Connection push fit Boiler Drain Pressure Gauge Capillary Relief Valve Insulation panel front Insulation panel side Pump Pressure gauge capillary C...

Page 25: ...ce the filter 15 4 10 Control Board Remove the facia bottom panel and carefully disconnect all the electrical connections Refer to Fig 33 Remove the cabinet and lower the facia panel as described in Section 14 3 Inspection and Servicing Disconnect the earth connection at the appliance Refer to Fig 45 Unscrew the four screws and remove the metal cover Refer to Fig 54 Lift out the control board Refe...

Page 26: ... fitting the replacement sensor 15 4 16 Overheat Thermostat Remove the cabinet and the inner casing Carefully pull off the connections Unscrew the two screws and remove the sensor Refer to Fig 58 Apply a small quantity of heat transfer paste to the face of the replacement sensor Carefully reposition the sensor so that the connections are away from the flue hood Reconnect the sensor 15 4 17 DHW Sen...

Page 27: ...ealant Loctite 575 when fitting the replacement air vent Remove the cap Refer to Fig 34 15 4 21 Primary Heat Exchanger Check that the appliance has been fully drained as described in 15 3 preceding Remove the combustion chamber as described in Section 14 3 Inspection and Servicing Remove the temperature sensors as described in 15 4 15 16 and 17 preceding Undo the four union connections and remove ...

Page 28: ...618 InnerCaseSeal WHS 1 87161216020 57 E27 620 Air Flow Switch Huba 605 99486 1 87161423870 59 E27 623 Control Board Junkers Heatronic 1 87483003360 63 375 696 Primary CH Sensor Elmwood 1 87161423020 63 375 696 DHW Sensor Elmwood 1 87161423020 66 299 495 Overheat Thermostat Elmwood 1 87161423890 69 E25 322 Spark Electrode Assembly Vulcano 1 8708107 0080 70 E25 323 Flame Sense Electrode Vulcano 1 8...

Page 29: ...29 ...

Page 30: ...ure set by control knob DEMAND END Overrun function see overleaf CENTRAL HEATING FUNCTION AND AND AND DOMESTIC HOT WATER FUNCTION MAIN SWITCH ON Green Light On Flow switch On Tap open DOMESTIC HOT WATER DEMAND Priority over CH demand Pump continue 4 seconds if primary temp above DHW setting Burner to MAX for 4 seconds Modulate gas to maintain delivered water temperature set by control knob Is CH i...

Page 31: ...tral heating sensor Return to normal off state AUTOFROSTAT FUNCTION Run pump 20 C END DHW DEMAND END CH DEMAND If primary temp over 85 pump cycles for 2 seconds every 10 seconds until temp below 85 Pump runs for 3 minutes If primary temp above 80 fan runs until temp below 80 C 35 seconds minimum If primary temp below 80 run fan for 35 seconds After 3 minutes the pump runs if primary temp over 95 u...

Page 32: ...uring your fault Then refer to the appropriate following section This fault finding system assumes that the appliance has been operating correctly until the time of failure PRELIMINARY CHECKS Preliminary electrical system checks are the first electrical checks to be carried out during a fault finding procedure On completion of the Service Fault Finding task which has required the breaking and rema...

Page 33: ... to boiler Replace control board Section 15 4 10 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 15 4 10 Remove control board from facia See Section 15 4 10 and sepa rate transformer from board Measure resistance across the two pairs of adjacent pins on the transformer Are any pair above 100 ohms Rep...

Page 34: ...onnector from board edge Does CH lamp now light Yes Correctly set or replace electronic programmer Yes Yes Red diode is damaged Replace control board Section 15 4 10 Replace control board Section 15 4 10 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 acros...

Page 35: ... FAIL POINT G Primary Overheat No Re fix sensor to pipe No No Repair or replace pump Section 15 4 18 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 Remove the multiway connector from board position ST16 Is there a short circuit across contacts 5 6 Fault caused by co...

Page 36: ...er 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 reading below 200 ohms Replace control board Section 15 4 10 If problem not solved replace gas valve Section 15 4 1 Repair or replace flame sensor Section 15 4 3 o...

Page 37: ... continuity from brown and violet wires to the multiway connector Check or replace CH sensor Section 15 4 15 Is there continuity from contacts 17 and 18 to DHW sensor Check or replace DHW sensor Section 15 4 17 Is there continuity from contacts 12 and 13 to CH sensor Repair or replace harness Repair or replace harness Repair or replace harness Is the multiway connector at board position ST16 pushe...

Page 38: ...ue for blockage Also investigate sense tubes and pressure switch Remove electrical connectors from pressure switch and restart boiler 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 15 4 22 Note In the unlikely event of th...

Page 39: ...5 4 15 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 Set pressure No No Repair wires or replace harness No Yes Yes Repl...

Page 40: ... subject to our official Conditions of Sale a copy of which may be obtained on application PUBLICATION 8 716 145 197 g 04 02 Bosch Group Worcester Heat Systems Limited Bosch Group Cotswold Way Warndon Worcester WR4 9SW Telephone 01905 754624 Fax 01905 754619 Technical Helpline 08705 266241 www worcester bosch co uk This manual is to be used in conjunction with the variant part number of the bar co...

Page 41: ...programmer to the facia and plug in the programmer connector into the four way connection on the board See Fig 1 Push the programmer into position ensuring that the lead is not trapped and that the clip has been properly engaged Replace white case Worcester Heat Systems Limited Cotswold Way Warndon Worcester WR4 9SW Telephone 01905 754624 Fax 01905 754619 Technical Helpline 0990 266241 Programmer ...

Page 42: ...1 49 50 9 14 CBi 41 311 50 51 28Si 47 311 51 52 14 19 CBi 41 311 52 53 C1 47 311 51 19 24 CBi 41 311 54 55 24CDi 47 311 30 31 WR325 52 311 02 28CDi 47 311 34 35 WH1 52 311 03 35CDi II 47 311 51 52 IMPORTANT THIS BOOKLET MUST BE READ FULLY IN CONJUNCTION WITH THE APPLIANCE INSTALLATION AND SERVICING INSTRUCTIONS THESE INSTRUCTIONS APPLY IN THE UK ONLY THESE INSTRUCTIONS ARE TO BE LEFT WITH THE USER...

Page 43: ...able for installation in dwellings with pitched or flat roofs The minimum distance the Flue Terminal Assembly shall extend above the surface of the roof is 300mm This dimension is measured from the outside surface of a flat roof or the highest point on a pitched roof to the underside of the air inlet flange on the terminal assembly See Fig 2 Important All the Flue items referred to in this section...

Page 44: ...ength to not exceed 800mm or 1550mm for 2 x 45 bends When measuring between the centre lines of flue ducts an allowance must be made for the relevant elbow Refer to Fig 3 Equivalent Length 4m 90 bends 0 5m 2m Equivalent length 2x750mm 1 5m 75mm MODEL 15SBi 79mm NONE NONE 24SBi EQUIVALENT FLUE LENGTHS UP TO 1M EQUIVALENT FLUE LENGTHS 1M TO 4M EQUIVALENT FLUE LENGTHS UP TO 725MM EQUIVALENT FLUE LENG...

Page 45: ... top of the appliance then the flue adaptor is not required 3 5 FLUE SUPPORT Flue assembly lengths over 2000mm should be appropriately supported Refer to Fig 6 and Section 5 4 3 6 FIRE STOP SPACER The fire stop spacer is supplied with the flue kit Refer to Fig 7 and Section 5 3 3 7 ROOF FLASHING The roof flashing is not supplied This is available as a proprietary item Selkirk or similar from the b...

Page 46: ... and pitched roofs Important The terminal assembly must extend at least 300mm above the surface or pitch of the roof The distance may vary depending upon the type of roof and surrounding structures In these instructions the distance is refered to as dimension F Refer to Fig 9 10 11 12 Fig 8 Marking out the flue assembly position Vertical Flue System no offset Appliance front Appliance front Vertic...

Page 47: ...han 300mm Duct Length H 92mm Derivation Dimension G 1100 Fmm Dimension H E G Refer to 2 2 for maximum duct length 4 Measurement of Ducts Air inlet flange Weather sealing collar Secure with screw provided and seal with silicone sealant Roof flashing not supplied Flat roof Pitched roof Flue terminal assembly 106mm diameter Fire stop spacer Air and flue duct extension kits 750mm Vertical flue adaptor...

Page 48: ...iameter marked on the inside surface of the roof Dimension K Refer to Fig 7 Note Dimension K for a pitched roof must go to the highest point of the hole diameter Determine dimension F Refer to Fig 1and 7 for the limiting figure Duct Length L 81mm Derivation Dimension G 1100 Fmm Dimension L K G Note The air duct must not be less than 100mm Air inlet flange Weather sealing collar Secure with screw p...

Page 49: ...ide surface of the roof Dimension K Refer to Fig 6 and 7 Note Dimension K For a pitched roof must go to the highest point of the hole diameter Determine dimension F which must not be less than 300mm Duct Length L 81mm Dimension G 1100 F mm Dimension L K G Air inlet flange Weather sealing collar Secure with screw provided and seal with silicone sealant Roof flashing not supplied Flat roof Pitched r...

Page 50: ...uts are square and free from burrs All dimensions refer to straight lengths and do not include the expanded ends Do not cut the expanded ends unless specifically instructed to do so 5 3 POSITION OF THE FIRE STOP SPACER ASSEMBLY Fit the fire stop spacer centrally over the hole in the ceiling Ensure the hole aligns with the flue spigot on top of the appliance casing 5 Installation of Flue Mark the f...

Page 51: ...at each stage of the system assembly that each section is properly aligned Each air and flue duct joint must be sealed and fixed Each air and flue duct connection to an elbow must be sealed with silicone sealant and fixed with the screws provided Support any sections of the system until they are permanetely fixed into place using suitable support brackets 5 5 ASSEMBLY OF DUCTS 5 5 1 AIR DUCTS Chec...

Page 52: ...s in the air duct Separate the assembly and apply silicone sealant to the outside of the air duct Re connect the assembly and fix with the screws provided Note The sealant and screws are not required for the flue duct Refer to Fig 13 5 10 SEAL THE TERMINAL ASSEMBLY TO THE ROOF From outside the building make good the roof structure and ensure the roof is weather sealed by fixing the roof flashing A...

Page 53: ...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 030d 08 01 Bosch Group Worcester Heat Systems Limited Cotswold Way Warndon Worcester WR4 9SW Telephone 01905 754624 Fax 01905 754619 Technical Helpline 0990 266241 www worcester bosch co uk ...

Page 54: ...h the appliance and or on the lighting instruction plate fitted to the appliance THESE INSTRUCTIONS APPLY IN THE UK ONLY THESE INSTRUCTIONS ARE TO BE LEFT WITH THE USER OR AT THE APPLIANCE CONFORMS TO THE ESSENTIAL REQUIREMENTS OF THE FOLLOWING DIRECTIVES 89 336 EEC Electromagnetic compatibility 73 23 EEC Low voltage Directive OFF TWICE ONCE ON ...

Page 55: ...nute period POWER UP CONDITION On power up when the battery back up has not been operational the pre set programme times will be in force ON1 OFF1 ON2 OFF2 MON FRI 6 30AM 8 30AM 4 30PM 10 30PM SAT SUN 7 00AM 9 00AM 4 00PM 11 00PM To return the programmer to the standard programme and 12 00am MON press the SET and buttons together BATTERY BACK UP Lifetime Lithium battery giving Display 1 Hour min 2...

Page 56: ...TO REPLACE THE PROGRAMMER Follow the preceding instructions 3 Programmer connection Fig 1 ST5 ...

Page 57: ...4 OFF TWICE ONCE ON ...

Page 58: ...he hours remember to take into account AM or PM press SET to lock in the hours Repeat the actions to set the minutes The display will show SET PROG TO SET THE PROGRAMME If you wish to change the programme press YES otherwise press SET twice to return to the run mode with the standard programme If you pressed YES then the display will ask SET MON FRI PROG If you want the weekday times to be the sam...

Page 59: ...ns for the central heating are OFF Off all the time TWICE On for two periods each day ONCE On for one period each day ON1 to OFF2 ON On all the time Operation of the SELECT button moves the arrow to the option required Mixing Once or Twice Options To have the Central Heating twice on some days and once on others programme the twice days as normal For the other days set ON1 and then OFF1 ON2 and OF...

Page 60: ...e Domestic Hot Water Temperature is controlled by the right hand knob on the facia Standard Programme To return to the standard programme press the SELECT and buttons together Refer to the User operating instruction leaflet or the lighting instruction plate on the appliance TO LIGHT AND STOP THE APPLIANCE 7 ...

Page 61: ... changed 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 8 716 145 227 ISSUE A 06 99 Worcester Heat Systems Limited Cotswold Way Warndon Worcester WR4 9SW Telephone 01905 754624 Fax 01905 754619 Technical Helpline 0990 266241 ...

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