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RD 628

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 GC NUMBER 47 108 14  (N.G.)

GB

APPLIANCE OUTPUTS

Domestic

Central Heating   

Hot Water       

Minimum               8.1 kW                        8.1 kW         
Maximum              28  kW                        28  kW         

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 RD 628

Page 1: ... with Natural Gas GC NUMBER 47 108 14 N G GB APPLIANCE OUTPUTS Domestic Central Heating Hot Water Minimum 8 1 kW 8 1 kW Maximum 28 kW 28 kW 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 ...

Page 2: ...obligations to record the information required by the initiative SERVICE To ensure continued efficient operation of the appliance it must be checked at regular intervals The frequency of servicing will depend upon the particular installation conditions and usage and can be up to 2 years The extent of the service required by the appliance is determined by the operating condition of the appliance wh...

Page 3: ...water temperature should be set to maximum 2 10 Safety The appliance must not be operated with the inner casing cover removed or without being full of water and pressurised The gas and electricity supplies must be turned off before working on the appliance Temperature monitoring controls are fitted to prevent overheating Automatic frost protection is provided together with automatic pump seizure p...

Page 4: ...GHT PACKAGED 50kg WEIGHT DRY 40kg Table 4 FLUE DETAILS HORIZONTAL FLUE WALL HOLE DIAMETER EXTERNAL FIX mm 110 INTERNAL FIX mm 130 STANDARD FLUE MINIMUM LENGTH mm 275 425 MAXIMUM LENGTH mm 725 EXTENDED FLUE MAXIMUM LENGTH mm 4000 FLUE ASSEMBLY DIAMETER mm 100 Table 2 FLOW RETURN DIFFERENTIAL NOTE Minimum uncut length NOMINAL BOILER RATINGS 10 Minutes After Lighting BOILER ADJUSTED FOR G20 Natural G...

Page 5: ...BER 78 2 SEDBUK BAND D 5 GAS SUPPLY SYSTEM BASED ON NG G20 TOTAL LENGTH OF GAS SUPPLY PIPE COPPER metres 3 6 9 12 GAS DISCHARGE RATE PRESSURE DROP mbar m3 h PIPE DIAMETER mm 8 7 5 8 4 6 3 9 22 18 0 12 0 9 4 8 0 28 Table 7 CLEARANCES mm INSTALLATION SERVICE UNVENTILATED COMPARTMENT ABOVE FLUEELBOW 30 30 150 IN FRONT OF APPLIANCE 600 600 240 BENEATH APPLIANCE 200 200 200 RIGHT AND LEFT HAND SIDE 10 ...

Page 6: ...dimensions and required clearances for installation servicing All dimensions in mm 30 150 10 10 6 B C D E 190 A B C D 20 A B C D E F View of underside of appliance showing connections Valves shown closed Fig 7 Pipework connections All dimensions in mm 114 600 740 230 360 200 200 F All dimensions in mm 114 Fig 5 Unventilated compartment clearances 230 200mm 150mm from the top of the flue elbow 80mm...

Page 7: ...be able to support the weight of the appliance Refer to Table 4 The specified clearances must be available for installation and servicing Refer to Table 8 and Fig 3 4 The appliance can be installed in a cupboard compartment to be used for airing clothes providing that the requirements of BS6798 and BS5440 Part 2 are followed Refer to Section 2 5 The airing space must be separated from the boiler s...

Page 8: ...cable a In addition the terminal should be not nearer than 150mm fanned draught to an opening in the building fabric formed for the purpose of accommodating a built in element such as a window frame Do not fit the flue terminal less than300mm from a neighbouring property including party walls and boundary lines Fig 8 Siting of the flue terminal The flue system must be installed following the requi...

Page 9: ...e maximum system design pressure is 1 5 bar If the pressure is above 2 65 bar when the appliance is at maximum temperature then an additional expansion vessel must be fitted as near to the appliance as possible in the return pipe The pressure gauge shows the system pressure Fill and pressurise the system through the filling loop supplied The system and the appliance must be fully vented Repeated v...

Page 10: ...suggested that a proprietary scale reducer is fitted in the mains cold water connection to the appliance Installation of a scale inhibitor assembly must be in accordance with the requirements of the local Water Company The water hardness can be determined by reference to the local Water Company An isolating valve should be fitted to allow servicing The appliance requires a maximum of 3 25m3 h of n...

Page 11: ...er Flow turbine ST16 2 blue green 2 brown brown blue blue brown green red yellow ST2 ST15 ST1 Pump Gas valve black white black Overheat cut off device DHW sensor Air Pressure Switch 2 green white black Code Plug Regulator Solenoid Valve Main Solenoid Valve red black blue green yellow black blue black red black red white ST5 Diagnostic Module ...

Page 12: ...ors Settings Regulator valve Spark electrodes Error indicator reset Red Main valve Flow sensor CH sensor DHW sensor Air pressure switch Flame sense Overheat cut off 24V programmer if applicable Gas valve mode switch CH Control knob DHW control knob Convert AC to low voltage electronics Electronics microprocessor Safety Low Voltage Flame detect indicator Red ST2 centre pole Ls for other features lo...

Page 13: ...at the assembly or template is level Mark the position of the fixing holes and the flue opening Refer to Fig 16 The diamond cut out indicates the centre line of the appliance Mark the centrelines of the pipe connections to aid the pre plumbing of the system pipework Pre plumbing is not recommended if no movement in the pipes is available Check the position of the fixing points and flue opening bef...

Page 14: ... it away from any electrics or where it might be a hazard Lower the facia to gain access The pipe must not be less than 15mm in diameter and must run continuously downward outside the appliance Refer to Fig 20 14 65 65 65 65 Wall Frame Wall Frame CH Flow DHW Flow Gas DHW Cold Inlet CH Return Fibre Washer Fig 17 Manifold assembly All dimensions in mm Fig 20 Relief valve drain connection 1 Fig 18 Fa...

Page 15: ... 23 24 25 and 26 The standard flue can be telescopically adjusted to any length between 425mm and 725mm measured from the centre of the turret without the need to cut the ducts Fix the flue assembly together using the self tapping screws provided Refer to Fig 23 It will only be necessary to cut the standard assembly if L is less than 425mm Cut the flue turret assembly and the terminal assembly by ...

Page 16: ...ssembly 11 10 Fitting the Flue Assembly with Access to the Terminal Prepare the flue duct assembly as described in Section 11 8 Apply the plastic tape to the air duct to be in contact with the external brickwork From inside push the assembly through the wall Align the flue turret and push fully onto the spigot on the appliance Tighten the clamping ring Refer to Fig 27 Make good the internal wall f...

Page 17: ...mm cut 100mm from the air duct and 120mm to cover the entry into the 45 or 90 elbow from the flue duct Refer to Fig 30 NOTE The flue system ducts between the elbows dimension Y requires the socketed ends of the first extension if two or more are used to be removed and the air and flue tubes to be cut to the same length Cut the ducts to a length Y 162mm Refer to Fig 29 The final section dimension Z...

Page 18: ...old have been tightened Undo the two screws and remove the connections cover panel Refer to Fig 32 Connect the mains supply lead to the appliance and secure in the cable clamp Make sure the lead is isolated before connection Refer to section 10 Check that there is sufficient loose lead to allow the release of the facia panel assembly and that the earth lead of the mains supply is longer than the l...

Page 19: ...s connector cover 2 Controls connector cover fixing screws 2 3 Facia control panel 4 Earth connection tags 5 Earth connection screws 6 Cable clamp 7 Fuse F1 2A slow 8 Cable clamp 9 ST15 Pump 10 ST1 Fan 11 Fuse F2 1 25A slow 12 Code plug 13 Commissioning switch gas valve mode switch 14 Internal controls connectors 15 Mains and external controls connectors 230 Volt ST2 Remove Link 230 V Room Thermos...

Page 20: ... see Fig 38 6 Fit two M4 screws complete with washers to each of the two con nections NB It is not possible to access the third screw hole so this can be left Do not attempt to turn the brass hexagon connectors 7 Ensure that the white plastic Control Screw on the Charging Link is turned fully into its closed position see Fig 39 8 Open the isolating valves on both the DHW inlet and CH return con ne...

Page 21: ... be fitted as close as possible to the appliance central heating return connection and pressurised to the same figure as the integral vessel 12 2 Set the Expansion Vessel Pressure The charge pressure of the expansion vessel as dispatched is 0 5bar which is equivalent to a static head of 5m 17ft The charge pressure must not be less than the static head at the point of connection A Schraeder type va...

Page 22: ...ogrammer is set to operate continuously Set the room thermostat and the central heating temperature control to maximum The burner will light and the appliance will modulate its output from minimum to maximum over a period of about two minutes Check that all the radiators are heating up evenly Shut down all but one of the radiators and observe the burner pressure fall Open all the radiators and che...

Page 23: ...e Fig 45 Observe LED on ADM flashing The flashing rate is 0 5 Hz the ADM is now in House Address Acquisition mode 9 Return to the Gateway and press SW1 Observe GREEN LED LHS through the side of the box flashing at about 3 4 Hz The Gateway is now in House Address Distribution mode House address Acquisition mode on the ADM and House Address Distribution mode on the Gateway must overlap Note the time...

Page 24: ...tification procedures Check the combustion performance Remove the cap from the sample point on the top of the appliance Refer to Fig 40 Connect the sampling meter With the appliance at maximum rate and stable in the DHW mode expect readings of CO2 5 6 6 4 CO 0 006 0 010 NB For flues greater than 725mm without a restrictor the CO2 may be up to 0 5 lower These figures cover all flue conditions Refit...

Page 25: ... Combustion chamber assembly 5 Spark electrode assembly 6 Inner case cover fixing bottom 7 Burner assembly 3 1 4 5 8 2 6 7 9 10 11 8 Combustion chamber fixing screw 9 Inner case 10 Fan assembly 11 Inner case cover fixing top 12 Combustion sensor point 13 Air pressure switch 13 12 ...

Page 26: ...and injectors are clear Clean the electrodes replace if there is any sign of deterioration Clean the heat exchanger Cover the gas inlet tube and remove any deposits from the heat exchanger from the top and bottom Carefully straighten any distorted fins on the heat exchanger Check the combustion chamber insulation and replace if there is any sign of damage or deterioration Refer to Section 15 5 Cle...

Page 27: ...se 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 onto lower lugs as necessary to gain access to the components Refer to Section 14 Inspection and Servicing 15 1 Gas Valve Unscrew the union connections above and below the gas ...

Page 28: ...move the spark electrode connections Unscrew the two burner bracket fixing screws Release the union connection beneath the burner and remove the burner from the appliance Refer to Fig 51 and 56 Do not omit the gasket when fitting the new burner 28 Fig 55 Flame sense electrode 1 3 2 1 Flame sense electrode 2 Fixing screw 3 Burner blade assembly RH Fig 56 Burner 1 Flame sense elctrode 2 Spark electr...

Page 29: ...ief Valve Remove the clip on facia cover cabinet and lower the facia onto the lower support lugs Check that the appliance has been fully drained Unclip and pull out the valve body Refer to Fig 59 15 8 Flow Switch Drain the DHW circuit as described at the start of Section 15 preceding Remove the clip on facia cover cabinet and lower the facia panel onto the lower support lugs Separate the in line c...

Page 30: ...ammer Remove the facia by gently pulling it away from the boiler to release the clips Remove the clock programmer assembly by releasing the clip at the top of the clock programmer and ease away from the control panel being careful not to pull on the connector lead Unplug the connector at the control board Refer to Fig 63 Comprehensive instructions are sent with the new control 15 13 Fan Remove the...

Page 31: ...ons to the new pump head Take care not to scratch the mating surfaces 15 19 Expansion Vessel It will be necessary to remove the appliance from the wall to replace the expansion vessel Refer to fig 40 Alternatively the specified replacement can be fitted into the heating system return as close to the appliance as possible Re fill and pressurise the system as described in Section 13 Commissioning 15...

Page 32: ...push up until the lugs are fully home Connect the RED tube to the ve connector and the WHITE tube to the ve connector 23 Sight Glass Remove and replace the inner casing cover complete Refer to Section 15 3 Inspection and Servicing Refer to Fig 47 32 Fig 67 Primary heat exchanger 1 2 3 4 5 6 1 Heat exchanger 2 CH flow return pipes 3 DHW inlet outlet pipes 4 Seal 5 Overheat thermostat 6 Primary sens...

Page 33: ... Expansion Vessel 1 8 715 407 154 0 16 E88 178 Control Board 1 8 748 300 417 0 17 E88 180 Fan Assembly 1 8 716 104 815 0 18 E88 181 Flow Sensor 1 8 716 146 164 0 19 E88 182 Seal Door Extrusion 1 8 716 104 609 0 20 E88 183 Transformer 1 8 747 210 294 0 21 E88 185 Flow Regulator 28 kW 1 8 716 141 253 0 22 E88 189 Code Plug 28 RSF 1 8 714 421 133 0 A001 Charging Link Assembly 1 7 716 192 281 A002 Ins...

Page 34: ...34 1 2 3 4 7 5 6 8 9 10 11 12 4 15 13 16 19 14 17 18 20 22 23 21 ...

Page 35: ...low temperature set by control knob 50 82 C DEMAND END Overrun function see overleaf CENTRAL HEATING FUNCTION AND AND DOMESTIC HOT WATER FUNCTION MAIN SWITCH ON Flow sensor signal Tap open DOMESTIC HOT WATER DEMAND Priority over CH demand Pump continue 4 seconds if primary temp above DHW setting Burner to MAX Modulate gas to maintain delivered water temperature set by control knob 40 60 C Is CH in...

Page 36: ...END CH DEMAND Pump runs for 3 minutes Pump on if primary temp above 80 until temp below 75 C AUTOFROSTAT FUNCTION Monitor central heating sensor Below 5 C 5 C to 9 C Above 9 C No demand and primary temperature below 8 C Internal Autofrostat demand Return to normal off state Fan low speed 35 seconds Fan low speed if primary temp above 80 C until below 75 C ...

Page 37: ...demand No CH function DHW OK No DHW function CH OK Flash once per second Ignition lockout Overheat lockout Internal error Flash 4 times per second No mains Voltage supply Fuse F1 or F2 blown Transformer or connector failed Board fault ADM Appliance Diagnostic Module fault No link at ST2 Ls to Lr or failed external control input to Lr Failed programmer Board fault Flow sensor failure DHW sensor LED...

Page 38: ... and separate transformer from board Measure resistance across the two pairs of adjacent pins on the transformer Is any coil above 100 ohms Replace transformer Yes Yes No Replace control board In the unlikely of this not solving the problem replace Dianostic Module No NOTE It is normal for there to be no facia lights if the boiler is in normal overtempera ture condition Continue this test if this ...

Page 39: ... and black wires terminals Is there continuity in the main harness Disconnect the 3 way in line connector to the turbine Is there 5VDC between the two outer pins main harness side Take care not to damage the pins No No Yes Yes Replace control board Replace main harness TEST C Yes Replace turbine No ...

Page 40: ...eading between 100 200 ohms In the unlikely event of this not solving the problem replace the Diagnostic Module Are the electrodes and gap and connections in good order Replace control board In the unlikely event of this not solving the problem replace the Diagnostic Module Remove brown connector from gas valve Is there continuity from brown wires to multiway connector Repair or replace harness Re...

Page 41: ... efficiency of the gas water heat exchanger If there is still a problem investigate flue problems or replace burner or injector or heat exchanger Does the flashing fault signal occur at the start of a demand If flashing occurs at the end of a demand Gas valve leak is detected Replace gas valve No Yes If flashing occurs during a demand Pump could be partially blocked Clean pump flush system Re fix ...

Page 42: ...h fully home No No No No No Yes Yes Yes Check the DHW sensor Is it correctly fitted onto the pipe with heat conductive paste between the pipe and sensor Yes No Re fix sensor onto pipe Is the Code plug fitted and fully home Fit push fully home Yes No TEST E Check or replace CH sensor Test resistance across contacts 10 and 11 black blue wires Is it open circuit Turn off electrical supply Remove fan ...

Page 43: ...fan or fan may not be running freely Inspect the flue Is it free of any restrictions Rectify flue problem Does the burner ignite burner light on and run for a short priod before the fault occurs Replace control board Repair cables or replace main harness Replace tubes If condensation has occurred also replace pressure switch and check condition of Venturi in the fan No No No No Yes Yes Yes Yes Tur...

Page 44: ...ximum TEST I No Yes It is not possible to easily isolate the fault The most likely causes are control board fail heat exchanger blocked or gas valve sticking Hot water temperature always too hot during a demand not regulating TEST H Hot water sensor could be off or poorly fixed to pipe Repair or replace Yes Problem occurs in the HW mode only Check flow sensor with boiler cool slowly open a HW tap ...

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Page 48: ...h the variant part number of the bar code below Manufactured exclusively for British Gas by Worcester Heat Systems Limited Bosch Group Cotswold Way Warndon Worcester WR4 9SW Telephone 01905 754624 Fax 01905 754619 PUBLICATION 8 716 105 430a 05 03 ...

Page 49: ...ROOM SEALED FLUE TERMINAL KIT For use on the Danesmoor Front Service Room Sealed Oil Appliances INSTALLATION INSTRUCTIONS The appliance flue system should be installed by a competent person ...

Page 50: ...100mm 4 inch to 150mm 6 inch 2 Standard RS flue kit for wall thickness of 230mm 9 inch to 400mm 15 inch 3 Long RS flue kit for wall thickness of 400mm 15 inch to 730 28 7 inch 3 Flue Lengths Bends and Extensions 3 1 The maximum flue length allowable is 2 5 metres as shown in Figs 1 and 2 3 2 Extension kits are available in 500mm and 1000mm sections 3 3 90 and 45 bends are available In addition to ...

Page 51: ......

Page 52: ...2 Total straight length of L1 L2 must not exceed 1500mm Distance from centre of boiler to centre of flue terminal S S 185 L1 185mm 66 100 mm L2 100mm L1 Y 104 H L3 42 100mm 185mm 218 58 L 2 L1 119 S Fig 2 Side discharge flue systems Centre of flue terminal to floor H 754 L1 Total straight length of L1 L2 must not exceed 2500mm Total straight length of L1 L2 L3 must not exceed 2500mm H 799 L1 Y Y 3...

Page 53: ......

Page 54: ... and fasten the elbow to the air box collar using the two self tap ping screws provided Where access to a fixing hole is not possible e g left and right flue options drill a new securing hole position at the same height as far as possible from the other screw 6 7 When fitting a vertical extension attach the exten sion to the air box and then attach the elbow to the extension in a similar manner to...

Page 55: ...L2 0mm ...

Page 56: ...e wall 6 46 Where vertical flue sections have been fitted raise the air box flue assembly by 3mm per 1 metre flue extension to allow for the flue tube expansion and fix the assembly in place the wall bracket is pro vided in the 1 metre extension kit 6 47 To prevent rain running back into the terminal it is recommended that the terminal exit slopes down by a few degrees This can be achieved by hold...

Page 57: ......

Page 58: ...RD 628 USER INSTRUCTIONS CUSTOMER CARE GUIDE G C NUMBER 47 108 14 ...

Page 59: ...bination appliance RD 628 appliances are made by Worcester Heat Systems and the strictest quality control standards are demanded throughout every stage of production The result is that your new RD 628 appliance offers you the very best of everything quality efficiency economical running costs proven reliability and value for money What s more you also have the assurance of our no nonsense 1 year p...

Page 60: ...nd system equipment A log book is dispatched with every appliance This is a vital document that needs to be completed by the installer at the time of installation It confirms that the boiler has been installed and commissioned according to the manufacturers instructions All CORGI Registered Installers carry a CORGI ID card and have a registration number Both should be recorded in your central heat...

Page 61: ...red to the tap or shower When hot water is no longer required the appliance pump or fan may continue to operate to dissipate the excess heat within the boiler Fig 1 System Diagram Automatic air vent Primary heat exchanger Circulating pump Fixed by pass Relief valve CH flow Domestic hot water flow Domestic cold supply CH return Relief valve discharge Domestic water flow turbine Expansion vessel ...

Page 62: ...atisfactory operation of the appliance Should water leaks be found in the system or excessive venting be required from any radiator a service engineer should be contacted and the system corrected The appliance must be fitted to a sealed heating system which is pre pressurised Your installer will advise you on the minimum and maximum pressure that should be indicated on the pressure gauge See Fig 2...

Page 63: ...at too high a temperature If using a pressure equalising valve set the Domestic Hot Water temperature control knob to the MAX position Hot and cold mains fed water can be supplied direct to an overrim flushing bidet subject to local water company requirements With all mains fed systems the flow of water from the individual taps will vary with the number of outlets operated simultaneously and the c...

Page 64: ...the boiler space by a perforated non combustible partition as described in BS 6798 1987 CIRCULATING PUMP This may be fitted with a speed adjuster If so it will be factory set at maximum and should not be changed FROST PRECAUTIONS If the appliance is not to be used for a long period of time and there is a likelihood of freezing then the appliance should be drained The Worcester Heat Systems technic...

Page 65: ...ully clockwise and anti clockwise positions By slightly reducing the flow of domestic water from the tap the delivery temperature of the water will be further increased This is of particular advantage in the winter for example to increase bath water temperature and to remove heavy grease deposits on plates etc Also this will provide an added advantage of reducing the delay before hot water is obta...

Page 66: ...rols Mains electricity On Off Fault indicator and reset button Flame detection indicator CH temp control knob DHW temp control knob System pressure gauge Fault indicator FLASHING SLOW Ignition lockout or once per second boiler overheat FLASHING FAST Appliance fault five times a second ...

Page 67: ... after approximately 1 hour A facia mounted mechanical programmer will require resetting once the operating switch has been set to O or the mains supply has been disconnected ELECTRICITY SUPPLY FAILURE If the electricity supply fails the appliance will not operate Once the supply is restored the appliance will return to normal operation If a programmer is fitted check that the settings have been m...

Page 68: ...e appliance will enter a lockout condition in the event of an air flow fault If the controls fail to detect the correct air flow through the appliance the electricity supply to the gas valve will be interrupted If an air flow fault has occurred the fault indicator will flash approximately five times per second The appliance will try to re light after a waiting period of approximately 5 minutes Che...

Page 69: ...If your RD 628 appliance should fail to operate correctly please call British Gas on APPLIANCE FAILS TO OPERATE 0845 9 60 50 40 IMPORTANT Do not touch or adjust any sealed component 12 ...

Page 70: ...der to realise its maximum working life and to ensure it continues to operate at peak efficiency and performance it is essential that your boiler receives regular competent servicing and annual maintenance checks beyond the initial 12 month guarantee period To arrange for a British Gas Three Star Cover agreement please call 0845 9 60 50 40 ...

Page 71: ...14 ...

Page 72: ...iate the first 12 month service has been carried out to the satisfaction of Worcester Heat Systems Limited when requested 3 That any product or part thereof returned for servicing under the guarantee must be accompanied by a claim stating the Model Serial Number Date of Installation 4 That Worcester Heat Systems Limited will not accept responsibility for damage caused by faulty installation neglec...

Page 73: ...s to maintain an effective and efficient customer service by establishing a reference and permanent record for your boiler IMPORTANT SERIAL NUMBER Copy the number off the Guarantee Card FOR YOUR OWN RECORD MODEL SERIAL NUMBER TYPE SIZE DATE OF INSTALLATION Do not forget to keep the Log book in a safe place MANUFACTURED EXCLUSIVELY FOR BRITISH GAS BY Worcester Heat Systems Limited Cotswold Way Warn...

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