Worcester CDi boiler guide

Vote for your‘Installer of the year’ atwww.worcester-bosch.co.uk24CDi, 28CDi & 35CDi IICOMBIWorcester supports theBenchmark code of practiceG.C. NUMBERSAPPLIANCE NATURAL GAS L.P.G.24CDi Fanned Flued (RSF) 47 311 30 47 311 3124CDi Balanced Flued (BF) 47 311 2924CDi Open Flued (OF) 47 311 32 47 311 3328CDi Fanned Flue (RSF) 47 311 34 47 311 3535CDi II Fanned Flue (RSF) 47 311 58 47 311 59USER INSTRUCTIONS &CUSTOMER CARE GUIDE

EXCELLENCE COMESAS STANDARDThank you for purchasing a Worcester CDi gas-fired combinationappliance.The CDi appliances are made by Worcester and the strictestquality control standards are demanded throughout every stageof production.Indeed, Worcester, part of the Bosch Group have led thefield in innovative appliancedesign and performancefor more than 40years.The result isthat your new WorcesterCDi appliance offers youthe very best of everything- quality, efficiency,economical running costs,proven reliability andvalue for money.What’s more, you also have the assurance of our nononsense1 year parts and labour guarantee.And, to keep your boiler operating at peak condition andefficiency, an optional maintenance scheme is available fromWorcester. Contact our Service Contracts team on 01905 754624for further details.CONTENTSPage No.Operating Instructions.................................... 3-11Fault and Breakdowns 12Maintenance andExtended WarrantyInformation ............ 13-14Guarantee Details .. 15-162

GENERALINFORMATIONGAS SAFETY (INSTALLATION AND USE)REGULATIONS 1998It is the law, in GB, that all gas appliances must be installed by acompetent person in accordance with the above regulations. Failureto install appliances correctly could lead to prosecution. It is in yourinterest and that of safety to ensure compliance with the law. Themanufacturer’s notes must not be taken, in any way, as over-ridingstatutory obligations.In GB, a competent person is someone registered with CORGI.All CORGI registered installers carry a CORGI ID card and have a registrationnumber. Both should be recorded in the BENCHMARK checklist.You can check that your installer is CORGI registered by callingCORGI on 01256 372300.WARNING: This appliance must be earthed and protected by a 3amp fuse.ELECTRICITY SUPPLY: 230V ~ 50HzIMPORTANT: To get the best from your Worcester CDi please readthese instructions carefully.NOTE: In the event of a fault the appliance should not be useduntil the fault has been corrected by a competent person.BENCHMARKThe Benchmark initiative is a code of practice to encouragethe correct installation, commissioning and servicing of domestic centralheating boilers and system equipment.A checklist can be found in the back of every installationmanual. This is a vital document that needs to be completed by theinstaller at the time of installation. It confirms that the boiler hasbeen installed and commissioned according to the manufacturersinstructions.In Eire the declaration found in IS 813 must be completed.Without completion of the checklist and/or declaration, manufacturersmay refuse to respond to a call-out request. It is important thatthe checklist and/or declaration are fully completed by your installer.GENERAL DESCRIPTION(See Fig.1.)The WORCESTER CDi MODELS are combined domestic hot waterand central heating appliances. They consist of a gas fired boiler havinga varying output of between:CHDHW24CDi 9.0 - 24kW 9.0 - 24kW28CDi 9.0 - 24kW 9.0 - 28kW35CDi II 10.5 - 27.5kW 9.5 - 35.3kWa heat exchanger to provide domestic hot water via the boiler, circulatingpump and water diverting valve. All the necessary controls toprovide mains fed domestic hot water and central heating.The appliances are supplied as standard with a manual operatingswitch. Alternatively a facia mounted programmer may have been fitted.The appliances can operate in one of two modes. Hot water only orhot water and central heating.3

Hot Water Mode:The appliance operates to supply only domestic hot water whenthe heating temperature mode is fully anti-clockwise, at the – positionor the timer is programmed to OFF mode.A flow restrictor is fitted within the appliance which limits a hotwater delivery rate to a maximum of:Fig. 1. System Diagram.Automatic airventCirculatingpumpWater towater heatexchangerDiverter valve24CDi28CDi35CDi II9.0 (±15%) litres/minute10.0 (±15%) litres/minute12.0 (±15%) litres/minuteHot Water and Central Heating mode:When a demand is madefor heating by the system controls(i.e. a programmer orroom thermostat), the pumpwill energise, circulating primarywater around the heatingsystem and the burnerBoilerGas to waterheat exchangerExpansionvesselPressurerelief valvewill light. The heat outputfrom the appliance in thismode has been factory set tomaximum. The appliance willoperate as necessary to maintainthe temperature of theradiators at the level set bythe adjustment of the HeatingTemperature Control Knob.(See Fig. 2.)If the system no longerrequires output to maintainthe desired room temperature,the burner will extinguish.The pump will continueto run for a short period todissipate the residual heatfrom the appliance and thenswitch off.The appliance will supplyheat to the central heatingsystem as required. A demandfor hot water at a tap or showerwill override the centralheating function for the periodof the domestic hot waterdemand.CHflowDomestichot wateroutDomestic CHcold supplyreturnSafety discharge4

Fig. 1a.GENERAL NOTESCENTRAL HEATING SYSTEMDuring the first few hours of operation of the central heatingsystem, check that all radiators are being heated at an even rate.Should the upper area of a radiator be at a lower temperature thanthe base of the radiator, it should be vented by releasing air throughthe venting screw at the top of each radiator. Make sure your installershows you how to carry out the operation. Repeated venting willreduce the quantity of water in the system and this must be replenishedfor safe and satisfactory operation of the appliance. Shouldwater leaks be found in the system or excessive venting be requiredfrom any radiator, your installer or heating engineer should be contactedand the system corrected.SEALED HEATING SYSTEMThe appliance can be fitted to a sealed heating systemwhich is pre-pressurised. In this case your installerwill advise you on the minimum and maximum pressurethat should be indicated on the pressure gauge. SeeFig. 2. Check regularly that this pressure is maintainedand contact your installer or maintenance engineer ifthere is a permanent significant drop in pressure indicatedon the gauge. If the system loses pressure itshould be re-pressurised as instructed by the installer(N.B. Maximum operating pressure 2.5 bar).GreyKnobFilling KeyRe-pressurising The System (See Fig. 1a).(If in doubt leave this procedure to your installer).Remove the bottom panel to gain access to the fillingloop assembly.Insert the bayonet end of the filling key into thecorresponding cut outs in the filling loop housing andtwist to lock the key in place.Turn the grey knob anti-clockwise to allow wateringress and fill until the required pressure is reached.Turn the grey knob clockwise to stop filling andremove the filling key by lining up the bayonet end ofthe key with the cut outs in the filling loop housing andwithdrawing the key.N.B. The key must always be removed from thefilling loop housing after the system has been filled toprevent accidental filling and to comply with Bylaw 14of the Water Bylaws Scheme.Store the key in a safe place for future use andrefit the bottom panel.OPEN VENTED HEATING SYSTEMThe appliance may be fitted to an open ventedheating system your installer will advise you. There isno need to observe the pressure gauge.5

CLEARANCES24,28CDi RSF 35CDi II 24CDi OF 24CDiBFLeft-hand side 10 10 10 10Right-hand side 10 10 10 10In Front 600 600 600 600Above 180 180 300 100Below 200 200 200 2006Minimum clearances in millimetres.Your installer will have provided adequate space around theappliance for safety and servicing. Do not restrict this space by theaddition of cupboards, shelves etc. close to the appliance.ROOM THERMOSTATA room thermostat may be fitted for control of the central heatingtemperature. It will be located in one room of the home. Themethod of setting a room thermostat varies with the type and manufacture.Refer to the instructions supplied with the room thermostat.THERMOSTATIC RADIATOR VALVESIf thermostatic radiator valves are fitted to the system then theymust conform to the requirements of BS2767. The radiator located inthe room where the room thermostat is sited must be controlled by athermostatic radiator valve.SHOWERS, BIDETS, TAPS AND MIXINGVALVESStandard hot and cold taps and mixing valves used with theappliance must be suitable for operating at mains pressure.Thermostatically controlled shower valves will guard against the flowof water at too high a temperature.If using a pressure equalising valve, set the Domestic Hot Watertemperature control knob to the ‘MAX’ position.Hot and cold mains fed water can be supplied direct to an overrimflushing bidet subject to local water company requirements.With all mains fed systems the flow of water from the individualtaps will vary with the number of outlets operated simultaneouslyand the cold water mains supply pressure to the property. Flow balancingusing ‘Ball-o-Fix’ type valves is recommended to avoid anexcessive reduction in flow to individual outlets.For further information contact The Worcester TechnicalHelpline. 08705 266241HOT AND COLD FLOWThe flow of water demanded from both hot and cold service outletsis dependent upon mains supply, it may not be possible in someinstallations to operate all outlets simultaneously.WATER MAINS FAILUREIt is important to note that in the event of a mains water supplyfailure, no tap water will be available until the mains supply isrestored. The appliance can still be used for heating provided that thesystem is of the sealed system type. Open vent central heating systemsshould be turned off until the supply is restored.USE IN HARD WATER AREASNormally there is no need for scale protection. However, in areasof exceptionally hard water supply it is recommended that an In-Linescale inhibitor be fitted.Installation should be strictly in accordance with the requirementsof the local Water Company. An isolating valve to facilitateservicing should be incorporated.

The water hardness may be determined using the standard testpaper or by reference to the local Water Company.Further information may be obtained from Worcester BoschTechnical Helpline.AIR SUPPLY FOR OPEN FLUED (O.F.)APPLIANCESYour installer will have made arrangements for an adequate supplyof fresh air to the appliance. Fresh air is required for combustion.Do not block up any air ways which may be let into a wall or door. Donot hang clothes or other combustible materials over the appliance oragainst the flue pipe.NOTE: Do not place anything on top of the appliance. If theappliance is fitted in a compartment do not use the compartment forstorage purposes unless it conforms to the requirements ofBS 6798:1987: Section 6. In particular, the flue pipe should not passthrough an airing cupboard space unless protected by a guard (such aswire mesh) concentrically spaced 13mm ( 1 /2in), as described in BS 6798:1987.VENTILATION OF BALANCED FLUED (BF)AND ROOM SEALED FANNED FLUE (RSF)APPLIANCESThese are room sealed appliances and any ventilation openingsin a wall or door must not be obstructed. Do not allow the flue terminalfitted on the outside wall to become obstructed or damaged.NOTE: Do not place anything on top of the appliance. If theappliance is fitted in a compartment do not use the compartment forstorage purposes unless it conforms to the requirements ofBS 6798:1987: Section 6. It is essential that the airing space is separatedfrom the boiler space by a perforated non-combustible partition asdescribed in BS 6798:1987.CIRCULATING PUMPThis may be fitted with a speed adjuster. If so it will be factoryset at maximum and should not be changed.FROST PRECAUTIONSIf the appliance is not to be used for a long period of time andthere is a likelihood of freezing, then the appliance should bedrained. The Worcester Technical Helpline will advise you on suitablefrost precautions. For short periods, the built-in frost protectionof the appliance will be adequate.SERVICEAnnual servicing is important to ensure continuing high efficiencyand long life of your appliance. Suitable servicing arrangements should bemade with a competent third party. In the event of any difficulty in makingsuitable service arrangements, Worcester personnel will be happy to discussregular servicing and offer a comprehensive maintenance contract.IMPORTANT: Do not touch or adjust any sealed compontent.WARNINGIf a gas leak exists, or is suspected, turn off the gas supply to theappliance at the service cock and consult your local service engineer.Do not touch any electrical switches to turn them either on or off.Open all windows and doors. Do not smoke. Extinguish all nakedlights.CLEANINGDo not use abrasive cleaners on the outer casing. Use a dampcloth and a little detergent.7

OPERATION OFCONTROLSOPERATING SWITCHIn the ‘ ’ position there is no mains electricity to theappliance.In the ‘I’ position mains electricity is connected to theappliance.CENTRAL HEATING TEMPERATURECONTROLThe position of this knob will determine the temperature of thewater delivered to the radiators between the ‘I’ and ‘MAX’ position.When the knob is turned anti-clockwise past the ‘I’ position towardsthe ‘ ’ (Summer Position), then the appliance will operate in theHOT WATER mode only and no heat will be delivered to the radiators.DOMESTIC HOT WATER TEMPERATURECONTROLThe position of this knob will determine the temperature of thewater delivered at the domestic hot water taps between the ‘ ’ andthe ‘MAX’ position.By slightly reducing the flow of domestic water from the tap, thedelivery temperature of the water will be further increased. This is ofparticular advantage in the winter, for example to increase bath watertemperature. Also this will provide an added advantage of reducingthe delay before hot water is obtained.FACIA MOUNTED PROGRAMMER (if fitted)Your installer may have mounted either a mechanical or an electronicprogrammer into the facia of your appliance. Operating instructionsare supplied with the programmer.RESET BUTTONPress this button in for five seconds if any of the indicator lightsare flashing slowly.SYSTEM PRESSURE GAUGEThe red needle has been set to show the sealed system pressurewhich is required for the appliance to operate effectively. The greyneedle will show the actual pressure in the system. This does notapply to any open vent system.8

INDICATOR LIGHTSMains electricity indicator:OFF : No mains electricity to the applianceON : Mains electricity is connected to theapplianceCentral heating demand indicator:OFF : No demand for heat to the centralheating circuitON : Central heating demandFLASHING SLOW : Ignition lockout(once per second)FLASHING FAST : Appliance fault (other than ignition(five times per second) lockout)Domestic hot water demand indicator:OFF : No demand for domestic hot waterON : Domestic hot water demandFLASHING FAST : Air flow fault (RSF). Flue gas spillage(OF)(five times per second)Central heating and domestic hot water demand indicators:BOTH FLASHING SLOW : Overheat cut-off(once per second)Flame detection indicator:OFF : Burner offON : Burner onFig. 2. Controls.Central heatingdemand indicatorDHW demandindicator Flame detectionResetindicatorbuttonMainselectricityindicatorOperatingswitchCH temperaturecontrol knobDHW temperaturecontrol knobSealed system pressuregauge9

10Fig. 3. CDi with front panel removed.ClipCirculatingpumpLocating pegTO LIGHT AND STOP THEAPPLIANCETO LIGHT THE APPLIANCECheck that the water valves to the central heating circuit are open.On sealed systems check that the grey needle on the pressuregauge is not below the required pressure.Switch on the mains electricity. The green power on indicator willlight. Set the room thermostat, if fitted, to maximum. Turn the centralheating temperature control knob to ‘MAX’. The red central heatingdemand indicator will light.The burner will light and the red flame detection indicator will light.Set the central heating and hot water temperature control knobsand the room thermostat, if fitted, to the desired temperature.TO STOP THE APPLIANCEFor Short PeriodsTurn the central heating temperature control knob fully anticlockwiseto the ‘ ’ position.For Long PeriodsTurn the operating switch to the ‘ ’ position. Switch off themains electricity.A facia mounted electronic programmer will retain its settings forabout two weeks, after which it will return to the factory setprogramme. The display will disappearExpansionvesselGas valveafter approximately 12 hours.A facia mounted mechanicalprogrammer will require resetting oncethe operating switch has been set to ‘O’,or the mains supply has beendisconnected.ELECTRICITY SUPPLYFAILUREIf the electricity supply fails theappliance will not operate. Once thesupply is restored the appliance willreturn to normal operation. If aprogrammer is fitted, check that thesettings have been maintained.OVERHEAT CUT-OFFTHERMOSTATThe appliance will enter a lockoutcondition in the event of overheating.An overheat cut-off thermostat isfitted to the appliance which willinterrupt the electricity supply to the gasvalve.If the overheat cut-off has operated,both the central heating and the hotwater demand indicators will flashtogether.

The appliance can be reset by pressing the reset button andholding in for 5 seconds.IGNITION LOCKOUTThe appliance will enter a lockout condition in the event of theburner failing to ignite.If the burner fails to light within a preset time of 10 seconds theelectricity supply to the gas valve will be interrupted.If ignition lockout has occurred, the central heating demandindicator will flash slowly (approximately once per second).The appliance can be reset by pressing the reset button andholding in for 5 seconds. Check that the gas supply has not beeninterrupted.If this condition continues to occur, then call a service engineer.AIR FLOW DEVICE (RSF ONLY)The appliance will enter a lockout condition in the event of anair flow fault.If the controls fail to detect the correct air flow through theappliance the electricity supply to the gas valve will be interrupted.If an air flow fault has occurred, the domestic water demandindicator will flash (approximately five times per second).The appliance will try to re-light after a waiting period ofapproximately 4 minutes Check that the flue terminal has not beenobstructed or damaged. If this condition continues to occur, then calla service engineer.FLUE SPILLAGE DEVICE (OF ONLY)The appliance is fitted with a device which detects the spillageof combustion products from the draught diverter. In the event of theflue becoming wholly or partly blocked this device will cut the gassupply to the burner. If the device has activated, the D.H.W. demandindicator will flash (approximately 5 times per second).The device automatically resets after a waiting period of approximately20 minutes. If the blockage remains the appliance will re-lightbriefly before the device operates again. Should the problem persistconsult your service engineer.REMOVAL AND REPLACEMENTOF THE FRONT PANEL (See Fig. 3)Removal:Holding the panel at the edges, slide it upwards to disengage theclips and ease the top edge forwards and upwards to raise it clear ofthe two pegs on the top edge of the facia.Replacement:Locate the two holes in the bottom edge of the front panel overthe two pegs on the top edge of the facia and reverse the removalprocedure.WARNING: Do not touch any component within the appliancewhen it is running as some may be very hot.11

APPLIANCE FAILS TOOPERATEA diagnostic system is provided which gives a flashing light displayon the facia panel. Press the reset button to attempt to restartthe appliance. If the appliance does not return to normal operationthen contact your installer or Worcester Bosch.More than 30% of all calls made to our contact centre reportingappliance faults or breakdowns prove to be false alarms, as there isoften a simple explanation for the apparent malfunction.So, to help you save time and money – not to mention frustrationand inconvenience – please refer to the General Information, Notes andLighting Instructions ensuring all controls are set correctly.If, after following the instructions the appliance still fails to operatecorrectly call the Worcester Contact Centre on 08457 256206.Arrangements will be made for an engineer to call as soon as possible.CALL-OUT CHARGESAll of our field service engineers are factory trained.If you request a visit from an engineer and your appliance hasbeen installed within the last 12 months, no charge will be made forparts and/or labour, providing:• The appliance was commissioned correctly on installation.• An appliance fault is found and the appliance has beeninstalled within the past 12 months.A call-out charge will be made where:• The appliance has been installed for over 12 months, or• Our Field Service Engineer finds no fault with the appliance(see note), or• The cause of breakdown is with other parts of your plumbing/heatingsystem, or with equipment not supplied by Worcester.NOTE: Invoices for attendance and/or repair work carried out onyour appliance by any third party will not be accepted.12

MAINTAINING YOURAPPLIANCEYour new Worcester CDi gas-fired appliance represents along-term investment in a reliable, high quality product.In order to realise its maximum working life, and to ensureit continues to operate at peak efficiency and performance, it isessential that your boiler receives regular, competent servicingand annual maintenance checks beyond the initial 12 monthguarantee period.Regular service contracts can be arranged with yourinstaller – however if you have difficulty making a satisfactoryarrangement simply contact Worcester on 01905 754624 forhelp.13

SERVICE CENTRESCONTACT NUMBERS:UK Contact Centre Tel. 08457 256 206UK Contact Centre Fax. 01905 757536Scotland only Fax. 01506 441 687Eire Tel: 01 494 0099OPERATING HOURS:Mon - FriSatSun7.00am to 8.00pm8.00am to 5.00pm9.00am to 12.00pmPlease contact our UK Contact Centre number where our friendly operatorswill book your call with one of our team of nationwide engineers.NOTE:Please refer to our website for our bank holiday opening hours.www.worcester-bosch.co.uk14

YOUR WORCESTERCDi COMBIGUARANTEEThis appliance is guaranteed from the date of installationsubject to the following conditions & exceptions.1. The appliance is guaranteed for aperiod of 24 calendar months subjectto the return of the guaranteecard within 30 days of installationand the first 12 months service andinspection having been carried outto the satisfaction of BBTThermotechnology UK Ltd. Pleasenote that this service is not coveredunder the terms & conditions of thewarranty and would therefore incura charge.2. That during the period of this guaranteeany components of the unitwhich are Proved to be faulty ordefective in manufacture will beexchanged or repaired Free of materialcharges and free of labourcharges if repaired directly by BBTThermotechnology UK Ltd.Invoices for attendance and repairof this appliance by third partieswill not be accepted for payment byBBT.3. That the householder may be askedto prove the date of installation andthat the appliance was correctlycommissioned. This informationmust then be documented in theBenchmark Gas BoilerCommissioning Checklist.4. That any product or part thereofreturned for servicing under theguarantee must be accompanied bya claim stating the model, serialnumber and date of installation.5. That BBT Thermotechnology UK Ltdwill not accept responsibility fordamage caused by faulty installation,neglect, misuse, accidentaldamage or the non-observance ofthe instructions contained in theInstallation and Users instructionsleaflets.6. That the appliance has been usedonly for normal domestic purposes,for which it was designed.7. That this guarantee applies only toequipment purchased and used inmainland Great Britain.This guarantee is given in addition to all your normal statutory rights.Worcester, Bosch Group is a trading name of BBT Thermotechnology UK Ltd.15

GUARANTEEREGISTRATIONYou should complete and return the postpaid GuaranteeRegistration Card within 30 days of purchase.The card will register you as the owner of your newWorcester CDi appliance and, while this will not affect yourstatutory rights in any way, it will assist us to maintain an effectiveand efficient customer service by establishing a referenceand permanent record for your boiler.IMPORTANT: SERIAL NUMBER. Copy the number off theGuarantee Card.FOR YOUR OWN RECORDMODELSERIAL NUMBER(See identity label inside appliance casing)TYPE/SIZEDATE OF INSTALLATIONCORGI CONTACTAll CORGI Registered installers carry a CORGI ID card andhave a registration number. Both should be recorded in yourcentral heating log book. You can check your installer isCORGI Registered by calling CORGI on 01256 372300www.worcester-bosch.co.ukWorcester, Bosch Group, Cotswold Way, Warndon, Worcester WR4 9SW.Telephone: 01905 754624 Fax: 01905 753130.Technical Helpline 08705 266241.Worcester, Bosch Group is a trading name of BBT Thermotechnology UK Limited8 716 114 647a (10/07)