Worcester GREENSTAR 24i Junior Installation Instructions Manual
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Worcester GREENSTAR 24i Junior Installation Instructions Manual

Worcester GREENSTAR 24i Junior Installation Instructions Manual

Wall hung rsf gas-fired condensing combination boiler
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See also: Installation, Commissioning & Servicing Instructions , Instructions for Installation and Servicing
INSTALLATION, COMMISSIONING AND SERVICING
INSTRUCTIONS
WALL HUNG RSF GAS-FIRED CONDENSING COMBINATION BOILER
GREENSTAR 24i/28i JUNIOR
FOR SEALED CENTRAL HEATING SYSTEMS AND MAINS FED DOMESTIC HOT WATER
The appliance is for use with Natural Gas or
L.P.G. (Cat II 2H3P type C13, C33 & C53)
Natural Gas
Liquid Petroleum Gas
UK/IE
Model
GC Number
24 ijunior
47-311-86
28 ijunior
47-311-87
24 ijunior
47-311-90
28 ijunior
47-311-91

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Summary of Contents for Worcester GREENSTAR 24i Junior

  • Page 1 INSTALLATION, COMMISSIONING AND SERVICING INSTRUCTIONS WALL HUNG RSF GAS-FIRED CONDENSING COMBINATION BOILER GREENSTAR 24i/28i JUNIOR FOR SEALED CENTRAL HEATING SYSTEMS AND MAINS FED DOMESTIC HOT WATER The appliance is for use with Natural Gas or L.P.G. (Cat II 2H3P type C13, C33 & C53)

  • Page 2: Table Of Contents

    CONTENTS CONTENTS 5.6.2 Checking the gas rate ....41 KEY TO SYMBOL AND SAFETY PRECAUTION . . 3 5.6.3 Domestic hot water: ....41 Explanation of symbols .

  • Page 3: Key To Symbol And Safety Precaution

    INSTALL CORRECTLY COULD LEAD TO PROSECUTION. • NOTICE indicates possible damage to property or IF YOU ARE IN ANY DOUBT CONTACT THE WORCESTER equipment, but where there is no risk of injury. TECHNICAL HELPLINE (0844 892 3366). • CAUTION indicates possible injury.

  • Page 4: Safety Precautions

    KEY TO SYMBOLS AND SAFETY PRECAUTION SAFETY PRECAUTIONS FITTING AND MODIFICATIONS Fitting the appliance and any controls to the appliance IF YOU SMELL GAS: may only be carried out by a competent engineer in B CALL NATIONAL GAS EMERGENCY SERVICE ON accordance with the current Gas Safety (Installation and 0800 111 999 Use) Regulations.
  • Page 5 70kW (net) : Air Supply - HARDWARE LITERATURE PACK: Qty. BS7593 Treatment of water in domestic hot water Greenstar 24i/28i Junior Installation, central heating systems Commissioning and Servicing Instructions BS6798 Installation of gas fired boilers of rated input Users Instructions...

  • Page 6: Appliance Information

    APPLIANCE INFORMATION APPLIANCE INFORMATION APPLIANCE Depth to wall 330mm (When fitted to wall frame) 700mm* 400mm * 710mm to top of case front 6720644741-01.1Wo STANDARD PACKAGE: Wall hung gas fired condensing combi boiler for central heating and domestic hot water Wall mounting frame Hardware literature pack (see checklist) Bottom Panel...

  • Page 7: Technical Data

    APPLIANCE INFORMATION TECHNICAL DATA DESCRIPTION NATURAL GAS Low NOx 24i & 28i UNIT junior junior junior junior junior Domestic Hot Water Minimum heat input 7.00 7.00 9.64 9.64 Maximum rated heat output Maximum rated heat input (net) 24.49 28.57 24.49 28.57 Low NOx Gas flow rate - Max.

  • Page 8: Layout

    APPLIANCE INFORMATION LAYOUT Fig. 1 Main boiler components 6 720 644 741a (2010/10)
  • Page 9 APPLIANCE INFORMATION Expansion Vessel Left side hand-hold for lifting boiler Flow temperature sensor (NTC) Plate to Plate heat exchanger Removable panel - for servicing Gas valve Electrode assembly Flue air pressure switch connection (not used) Overheat thermostat Securing nut - Air/Gas manifold clamp Fan guard Silicon tube - heat exchanger air vent Manual vent point...
  • Page 10 APPLIANCE INFORMATION Fig. 3 Additional components Burner ON indicator light (green) CH return isolator Power ON/OFF indicator/fault diagnostic light (blue) DCW mains in isolator Position for optional programmer Gas inlet connection 22 mm & isolator Reset button DHW connection System pressure gauge CH flow isolator ECO button Condensate connection...

  • Page 11: Pre-Installation

    PRE-INSTALLATION PRE-INSTALLATION CLEANING PRIMARY SYSTEMS INHIBITOR NOTICE: Add a suitable inhibitor or combined inhibitor/anti- B All the following Pre-Installation sections freeze, if the system is exposed to freezing conditions, to must be read and requirements met the heating system in accordance with the before starting boiler or flue installations.

  • Page 12: Mains Supply

    PRE-INSTALLATION MAINS SUPPLY 3.2.4 WATER SUPPLY 3.2.1 ELECTRICAL SUPPLY WATER MAINS PRESSURE: • Supply: 230V - 50 Hz, 140 Watts • Minimum mains water pressure: 1.3 bar for 24 and 28i • Cable: PVC insulated 0.75 mm (24 x 0.2 mm) Junior, for maximum performance.

  • Page 13: Water Systems And Pipe Work

    PRE-INSTALLATION WATER SYSTEMS AND PIPE WORK PLASTIC PIPE WORK: SEALED PRIMARY SYSTEM: • Any plastic pipe work must have a polymeric barrier NOTICE: ARTIFICALLY SOFTENED WATER with 600mm (minimum) length of copper pipe MUST NOT BE USED TO FILL THE CENTRAL connected to the boiler.

  • Page 14: Condensate Pipe Work

    PRE-INSTALLATION CONDENSATE PIPE WORK Alternatively if the first option is not possible an internal NOTICE: kitchen or bathroom waste pipe, washing machine B Where a new or replacement boiler is waste pipe etc. can be used. being installed, access to an internal “gravity discharge”...

  • Page 15: External Connections

    PRE-INSTALLATION 3.4.2 EXTERNAL CONNECTIONS FITTING AN EXTERNAL AIR BREAK NOTICE: Freezing conditions • Refer to figure 9 when a rain water down pipe, that B Pipe work length should be kept to a goes directly into a sewer that carries both rainwater minimum and the route as vertical as and foul water, is used to dispose of condensate.
  • Page 16 PRE-INSTALLATION CONDENSATE SOAK AWAY • The condensate drainage pipe may be run above or below the ground to the soak away. • The examples shown on this page run above ground. • The soak away must use a 100mm Ø plastic tube with two rows of three 12 mm holes on 25 mm centres and 50 mm from the bottom of the tube.

  • Page 17: Pressure Relief Pipe Work

    PRE-INSTALLATION PRESSURE RELIEF PIPE WORK NOTICE: B The pressure relief valve is a safety device for the boiler and if activated may discharge boiling water or steam through the relief valve drain pipe. B Care should be taken when siting the outlet pipe so that it does not cause an obstruction or discharge above a window, entrance or other public access...

  • Page 18: Boiler Location And Clearances

    PRE-INSTALLATION BOILER LOCATION AND CLEARANCES 3.6.1 INSTALLATION 3.6.3 COMPARTMENTS This boiler is only suitable for installing internally within Follow the requirements of BS6798 and BS5440 Part 2 a property at a suitable location onto a fixed, rigid and note: surface at least the same size as the boiler and capable •...

  • Page 19: Boiler Clearances- Unventilated Compartments

    PRE-INSTALLATION 3.6.5 BOILER CLEARANCES- UNVENTILATED COMPARTMENTS The tables below show the options for the minimum space required to install and service the boiler inside an unventilated compartment. 3.6.6 INSTALLATION CLEARANCES - UNVENTILATED COMPARTMENTS CAUTION: CLEARANCES B Top and bottom clearances must not be reduced below the values shown in table 13 as they are the minimum clearances required for servicing.

  • Page 20: Plumbing Manifold

    PRE-INSTALLATION PLUMBING MANIFOLD 3.7.1 CONNECTIONS 1 2 3 Heating System 22mm compression fittings 15mm compression fittings 22mm compression fitting Tab. 16 Use the fittings supplied in the Hardware literature pack. • If the boiler pipes are to be run behind the appliance ensure that the pipes pass through the slot in the white cardboard guide (A).

  • Page 21: Flue Options

    PRE-INSTALLATION FLUE OPTIONS Maximum total flue length (mm) FLUE TYPE 60/100 80/125 Telescopic horizontal flue assembly 1,070 Horizontal flue extension 4,600 13,000 Horizontal flue with 1 x 90° bend 2,600 11,000 Horizontal flue with 2 x 90° bends 11,000 High level horizontal flue 4,600 13,000 High level horizontal flue with 2 x 90°...
  • Page 22 PRE-INSTALLATION 350 mm 570 mm 130 mm Min 500 mm 300 mm Flat roof 6720643895-12.1Wo 6 720 644 741a (2010/10)

  • Page 23: Flue Terminal Positions

    PRE-INSTALLATION FLUE TERMINAL POSITIONS All measurements in millimetres Dormer Window 1,500 Velux Window Drainpipe 1,200 1,500 Boundary Window 6720643895-13.2Wo Fig. 18 Flue terminal positions NOTICE: B All measurements are the minimum clearances required. B Terminals must be positioned so to avoid combustion products entering the building. B Support the flue at approximately one metre intervals and at a change of direction, use suitable brackets and fittings (Flue bracket part numbers.: 100mm - 7 716 191 092, 125mm - 8 716 110 272).

  • Page 24: Plume Management Terminal Positions

    PRE-INSTALLATION 3.10 PLUME MANAGEMENT TERMINAL POSITIONS All measurements in millimetres ±45° Plume management deflector: Flue Exhaust Outlet 180° Air Intake ±80° 1,200 Balcony Window Window Window Door Boundary Drainpipe 6720643895-14.1Wo Fig. 19 Plume terminal positions NOTICE: B All measurements are the minimum clearances required. B Refer to figure 18 for all concentric flue terminal positions unless the flue position is specified on the figure above “Plume terminal positions”.

  • Page 25: Installation

    INSTALLATION INSTALLATION IMPORTANT HANDLING INSTRUCTIONS: WARNING: All the previous “Pre- • It is advised that two people are used to carry the Installation” sections must be read and the carton from the van to the point of delivery. requirements met before starting boiler or flue installation.

  • Page 26: Wall Mounting Template & Flue Openings

    INSTALLATION WALL MOUNTING TEMPLATE & FLUE OPENINGS WARNING: BEFORE DRILLING: ENSURE THAT THERE ARE NO PIPES, ELECTRICAL CABLES, DAMP PROOF COURSES OR OTHER HAZARDS . SAFETY: All relevant safety precautions must be undertaken. Protective clothing, footwear, gloves and safety goggles must be worn as appropriate.

  • Page 27: Unpacking The Appliance

    INSTALLATION UNPACKING THE APPLIANCE 1. Outer carton 2. Inner sleeve (unwrap from front) 3. Packing base 4. Protective wrapping 5. Appliance outer case B Remove outer carton (1) and place safely away from the working area. B With the outer packaging removed and the inner sleeve (2) still in place gently lay the boiler on its back.

  • Page 28: Boiler Connections

    INSTALLATION BOILER CONNECTIONS 1. Pull the extended lever forward and down until there CAUTION: ISOLATE THE MAINS GAS is no further travel. SUPPLY BEFORE STARTING ANY WORK AND OBSERVE ALL RELEVANT SAFETY PRECAUTIONS. GAS AND WATER CONNECTIONS: B Remove wall mounting template and secure the wall mounting frame to the wall with the appropriate fixings for the boiler weight and wall type.
  • Page 29 INSTALLATION Connect the expansion vessel flexible pipe to the NOTICE: The pressure relief connector hydraulic manifold situated to the left of the pump: must be repositioned after the boiler has B Remove and discard the plastic cap from the been correctly mounted to the wall expansion vessel flexible pipe.

  • Page 30: Flue Installation

    INSTALLATION FLUE INSTALLATION 4.5.2 REDUCING THE TELESCOPIC FLUE LENGTH HORIZONTAL FLUE (60/100mm diameter) Ensure that the “TOP” label is facing up For vertical flues and 80/125mm horizontal flues, please before securing the flue section to the refer to separate instructions supplied with the flue kit. turret.

  • Page 31: Installing The Telescopic Flue

    INSTALLATION 4.5.3 INSTALLING THE TELESCOPIC FLUE Refer to figure 36. B If fitting the outer seal from outside the building, slide the outer wall seal onto the terminal as shown. 1. Set the flue length to the distance required, secure with screws provided.

  • Page 32: Flue Terminal Plume Re-Direction

    INSTALLATION 4.5.4 FLUE TERMINAL PLUME RE-DIRECTION NOTICE: Outlet position The flue discharge can be re-directed allowing some B The flue terminal outlet position must plume redirection control, alternatively, a complete follow those stated in the relevant plume management system can be fitted to the flue appliance instruction manual.

  • Page 33: Condensate Connection

    INSTALLATION CONDENSATE CONNECTION 1. Push the syphon onto the sump assembly, until the lug on the sump is fully engaged with the slot on the Never terminate or discharge into any open source, back of the syphon assembly and the clip is engaged including;...

  • Page 34: Electrical

    INSTALLATION ELECTRICAL Refer to figure 47. CAUTION: ISOLATE THE MAINS 1. Unscrew the three screws in the control panel. ELECTRICITY SUPPLY BEFORE STARTING 2. Remove the connections cover. ANY WORK AND OBSERVE ALL RELEVANT SAFETY PRECAUTIONS. The boiler is pre-wired with a mains supply cable.
  • Page 35 INSTALLATION 230 V ROOM STAT/CLOCK ST10: PROGRAMMABLE THERMOSTAT The figures below show the options of room thermostat Programmable 230V with programmer, programmer only, or room thermostat Thermostat MAINS only. SUPPLY The programmable thermostat may be a NC NO hard wired or RF type. live This diagram is applicable for the hard wired neutral...

  • Page 36: Commissioning

    COMMISSIONING COMMISSIONING CONVERT BOILER TO LOW NOx NOTICE: Low NOx ST10 B The Low NOx performance is achieved just by changing the code plug. No setting need to be made. The boiler can be converted to a “Low NOx” version. ST15 The “Low NOx”...

  • Page 37: Pre-Commissioning Checks

    COMMISSIONING PRE-COMMISSIONING CHECKS B Check that the condensate pipe (1) has been connected to the syphon. CAUTION: ISOLATE THE MAINS ELECTRICITY SUPPLY BEFORE STARTING ANY WORK AND OBSERVE ALL RELEVANT SAFETY PRECAUTIONS. Check that the service and water pipes are connected to the correct position on the manifold.

  • Page 38: The System

    COMMISSIONING FILLING THE SYSTEM ENSURE THAT THE SYSTEM HAS BEEN CLEANED AS ON PAGE 11 OF THESE INSTRUCTIONS. 1. Turn on the water main and open the system valves. FLUSHING (Central Heating): 2. Open all radiator valves. B Switch off the boiler. 3.

  • Page 39: Starting The Appliance

    COMMISSIONING STARTING THE APPLIANCE CAUTION: RUNNING THE APPLIANCE B Never run the appliance when the appliance/system is empty or partially filled. Fig. 61 Control panel Switching the appliance on/off: Turn the boiler CH temperature control (1) to maximum. The burner on indicator (2) illuminates GREEN when the B Turn on mains power supply, the power on indicator burner has lit.

  • Page 40: Commissioning

    COMMISSIONING COMMISSIONING Ensure inlet pressure is satisfactory with all NOTICE: The combustion settings on this gas-fired boiler have been checked, adjusted other gas appliances working. and preset at the factory for operation on the gas type defined on the data plate. GAS PRESSURE WITHIN THE SYSTEM No measurement of the combustion values Refer to the figures below for natural gas or L.P.G gas...

  • Page 41: Checking The Gas Rate

    COMMISSIONING 5.6.2 CHECKING THE GAS RATE B The gas rate should be measured at the gas meter after 10 minutes operation at maximum. See technical data section at the front of this manual. B Where a gas meter is not available (e.g. L.P.G.) the CO/CO must be checked to the units shown in the setting of the air/gas ratio, refer to section 6.6.

  • Page 42: Finishing Commissioning

    COMMISSIONING FINISHING COMMISSIONING 5.7.1 REPLACE OUTER CASING: 5.7.3 INSTALLING BOTTOM PANEL B Replace outer casing making sure that the securing B The bottom panel slides onto two ledges (C) either points are properly located. side of the boiler frame. B Replace top two screws (1). B Hold the panel up against the underside of the boiler and slide towards the rear, until there is no more B Tighten bottom two screws (2).

  • Page 43: Service And Spares

    SERVICE AND SPARES SERVICE AND SPARES INSPECTION AND SERVICE COMPONENT ACCESS 1. Removing outer case CAUTION: TURN OFF THE GAS SUPPLY AND – Remove bottom panel by pushing it fully back and ISOLATE THE MAINS SUPPLIES BEFORE then pulling it forward and down to remove. STARTING ANY WORK AND OBSERVE ALL RELEVANT SAFETY PRECAUTIONS.

  • Page 44: Check The Gas Inlet Pressure

    SERVICE AND SPARES CHECK THE GAS INLET PRESSURE CHECKING FLUE INTEGRITY Refer to section 5.6.1 for more information The integrity of the flue system and performance of the boiler can be checked via the flue turret sample points. NOTICE: B Ensure that the gas inlet pressure is Flue gas sample point satisfactory with all other gas appliances Air inlet sample point...

  • Page 45: Fan Pressure Test

    SERVICE AND SPARES FAN PRESSURE TEST B Remove the cover and connect a digital manometer to This test is to determine if the heat cell the fan pressure test point. requires cleaning/attention. B After measurement replace test point cover. B The pressure will read negative, refer to the chart in figure 73.

  • Page 46: Flue Gas Analysis

    SERVICE AND SPARES FLUE GAS ANALYSIS COMBUSTION TEST: B Connect the flue gas analyser to the flue gas sampling point as shown in the figure below. B Run the boiler at maximum output for at least 10 minutes. B Check the CO/CO readings against the information in table 24 CO/CO settings on page 47.

  • Page 47: Setting The Air/Gas Ratio

    SERVICE AND SPARES SETTING THE AIR/GAS RATIO B Measure the CO/CO and check against the table 24 NOTICE: THE SETTING OF THE GAS RATIO below. MUST BE CARRIED OUT BY A COMPETENT If required set the minimum CO/CO via adjuster (2) PERSON.

  • Page 48: Cleaning The Heat Exchanger

    SERVICE AND SPARES CLEANING THE HEAT EXCHANGER 1. Refer to figure 79 and undo the securing nut on the NOTICE: COMBUSTION TESTING top of the heat exchanger and remove the retaining B Combustion testing must be carried out plate assembly. by a competent person.
  • Page 49 SERVICE AND SPARES BURNER REMOVAL BAFFLE REMOVAL Refer to figure 81 Refer to figure 82. 1. Remove clamping plate. 1. Remove top baffle. 2. Remove spark/flame electrode assembly and seal 2. Remove lower baffle. from the top of the heat exchanger. If the lower baffle is stuck, it may be 3.
  • Page 50 SERVICE AND SPARES ACCESS COVER REMOVAL THE HEAT EXCHANGER DOES NOT HAVE TO BE REMOVED TO CLEAN. Refer to figure 83. The heat exchanger is shown removed from 1. Remove the two pozi-drive screws the boiler to illustrate cleaning more clearly. 2.

  • Page 51: Replacement Of Parts

    SERVICE AND SPARES REPLACEMENT OF PARTS CAUTION: TURN OFF THE GAS SUPPLY To gain access to the following components AND ISOLATE THE MAINS SUPPLIES he outer case has to be removed: BEFORE STARTING ANY WORK AND B Primary sensor OBSERVE ALL RELEVANT SAFETY B Overheat thermostat PRECAUTIONS.

  • Page 52: Flue Overheat Thermostat (With Grommet)

    SERVICE AND SPARES 6.8.4 FLUE OVERHEAT THERMOSTAT 6.8.5 MOVING CONTROLS TO SERVICE POSITION (WITH GROMMET) To remove the following components To remove and replace the thermostat either: require the control box must be moved in to B Using a small terminal screwdriver, prise the the service position: thermostat and grommet from the plastic housing.

  • Page 53: Gas Valve

    SERVICE AND SPARES 6.8.6 GAS VALVE 6.8.7 AIR/GAS MANIFOLD AND FAN ASSEMBLY Refer to figure 90 The following components require the B Isolate gas supply at boiler gas cock. air/gas manifold and fan assembly to be removed: 1. Remove wire clip from gas valve outlet. B Fan electrode assembly 2.

  • Page 54: Fan

    SERVICE AND SPARES B Rotate fan and air/gas manifold assembly (1.) around the top of the heat exchanger until the lug on the air/ gas manifold is visible. 6720643895-63.1Wo 6720643895-81.1Wo Fig. 93 Rotate the air/gas manifold assembly Fig. 94 Dismantling the air/gas manifold assembly B Lift up assembly and remove from boiler.

  • Page 55: Electrode Assembly And Burner

    SERVICE AND SPARES 6.8.9 ELECTRODE ASSEMBLY AND BURNER 6.8.10 HEAT EXCHANGER Refer to figure 96. B Isolate flow and return valves then drain the boiler. B Disconnect spark electrodes and flame sensor B Remove syphon. connection. B Remove the air/gas manifold and fan. B Remove clamping plate.
  • Page 56 SERVICE AND SPARES Refer to figure 99. 1. Release the clip. 2. Move the lower exhaust connector up B Remove the complete exhaust assembly. Fig. 101 Heat exchanger removal B Reassemble and check combustion as stated in the Fig. 99 Release lower exhaust connection gas conversion section.

  • Page 57: Access To Boiler Control Components

    SERVICE AND SPARES 6.8.11 ACCESS TO BOILER CONTROL COMPONENTS 6.8.13 TRANSFORMER/PCB 1. Remove three screws. Refer to figure 105. 2. Remove cover from control. B Disconnect all electrical connections from the control. 1. Remove five screws retaining the rear panel of the control.

  • Page 58: Replacing Controls

    SERVICE AND SPARES 6.8.14 REPLACING CONTROLS Refer to figure 108. 1. Using a suitable tool, press the button upwards. NOTICE: 2. Slide the control support bracket to the left. B Do not replace the control unit if a CO/CO analyser is NOT available. The control unit is supplied within its plastic housing.

  • Page 59: Syphon Removal

    SERVICE AND SPARES 6.8.15 SYPHON REMOVAL 6.8.16 DIVERTER VALVE MOTOR B Connect electrical power to the appliance. Removal of the syphon assembly will give B Enter the service mode to ensure that the diverter access to the Auto Air Vent. valve is in the mid position (there is no need to drain the appliance).

  • Page 60: Auto Air Vent

    SERVICE AND SPARES 6.8.18 AUTO AIR VENT 6.8.19 DHW TEMPERATURE SENSOR B Ensure the domestic hot water circuit is fully drained. Removal of the syphon assembly will give B Disconnect the electrical connection from the sensor. access to Auto air vent. Refer to page 59. 1.

  • Page 61: Flow Sensor, Flow Restrictor Housing And Filter

    SERVICE AND SPARES 6.8.21 FLOW SENSOR, FLOW RESTRICTOR HOUSING 6.8.23 DRAIN TAP AND FILTER B Ensure the appliance has been fully drained. B Ensure the domestic hot water circuit is fully drained. 1. Rotate the drain tap fully anticlockwise and push in. B Disconnect the electrical connection to the turbine.

  • Page 62: Hydraulic Block Removal

    SERVICE AND SPARES 6.8.25 HYDRAULIC BLOCK REMOVAL B Take care not to snag the harness. Remove the syphon assembly. Refer to Syphon assembly removal page 59 B Ensure the appliance has been fully drained . B Disconnect the electrical connections to the NTC sensor, turbine and pump.

  • Page 63: Dhw Pressure Relief Valve

    SERVICE AND SPARES 6.8.27 DHW PRESSURE RELIEF VALVE 6.8.28 DHW PLATE HEAT EXCHANGER Remove the Hydraulic block from the boiler NOTICE: DEVICE REMOVAL (See 6.8.25 removing the Hydraulic Block). B If the hydraulic block has already been removed from the appliance, steps 3 and 4 are all that is required to remove the 1.

  • Page 64: Expansion Vessel

    SERVICE AND SPARES 6.8.30 EXPANSION VESSEL The expansion vessel can be replaced with the boiler in Expansion vessel replacement (Removing the Boiler) position if there is a side exit flue fitted and a minimum B Isolate electrical supply. clearance of 340mm above the boiler casing. If a vertical B Isolate system and gas connections at the service flue is fitted then a similar clearance to one side of the valves.

  • Page 65: Short Parts List

    SERVICE AND SPARES SHORT PARTS LIST Burner Gas Valve 8 717 204 453 0 8 718 120 619 0 8 716 111 325 0 GC No. H26 536 GC No. H26 538 GC No. H26 540 Control board Flue overheat Electrodes HT3 Bus enabled thermostat...
  • Page 66 SERVICE AND SPARES Automatic air vent Fusing element set Pressure relief 8 744 503 010 0 8 716 106 445 0 valve Containing: 8 716 106 431 0 Fuse F1 2.5 Amp GC No. H09 750 Fuse F2 1.6 Amp Fuse F3 0.5 Amp Expansion vessel Seals kit...

  • Page 67: Fault Finding And Diagnosis

    (i.e. not This fault finding information is for guidance a first installation error). only. Worcester cannot be held responsible for costs incurred by persons not deemed to PRELIMINARY CHECKS : Preliminary electrical system be competent.
  • Page 68 FAULT FINDING AND DIAGNOSIS Blue light Lockout indication reset button Fault Possible solution/check Slow flash Flashing Ignition lockout B Gas present and at correct pressure? (mostly (reset B Gas valve off, flashes required) – Check that there is 35V d.c. to each solenoid –...

  • Page 69: Circuit Diagram

    Blue ST17 Yellow Green Black Blue Blue Purple Purple Orange Orange WORCESTER 24V CONTROLS OPTION, PLUG IN POINT Green (under blanking cover on fascia) Black Yellow Fuse F3, slow T 0.5 A 230V/AC Yellow Yellow Fuse F2, slow T1.6 A...

  • Page 70: Central Heating Function

    FAULT FINDING AND DIAGNOSIS CENTRAL HEATING FUNCTION Fig. 128 CH function 6 720 644 741a (2010/10)

  • Page 71: Preheat And Dhw Function

    FAULT FINDING AND DIAGNOSIS PREHEAT AND DHW FUNCTION Fig. 129 Pre-heat and DHW 6 720 644 741a (2010/10)

  • Page 72: Protection Function

    FAULT FINDING AND DIAGNOSIS PROTECTION FUNCTION AUTOMATIC INTERNAL FROST FUNCTION Internal boiler Internal boiler Pump switches off temperature Pump runs temperature after a 3 minute between rises above 9°C overrun period 8°C & 5°C Boiler automatic frost function (monitors internal boiler primary temperature) Central heating Internal boiler...
  • Page 73 FAULT FINDING AND DIAGNOSIS 6 720 644 741a (2010/10)
  • Page 74 Failure to install and commission according to the manufacturer’s instructions and complete this Benchmark Commissioning Checklist will invalidate the warranty. This does not affect the customer’s statutory rights. If yes, and if required by the manufacturer, has a water scale reducer been fitted? CONDENSING BOILERS ONLY The condensate drain has been installed in accordance with the manufacturer’s instructions and/or BS5546/BS6798 If the condensate pipe terminates externally has the pipe diameter been increased and weatherproof insulation fitted?

  • Page 75: Service Record

    Service Record It is recommended that your heating system is serviced regularly and that the appropriate Service Interval Record is completed. Service Provider Before completing the appropriate Service Record below, please ensure you have carried out the service as described in the manufacturer’s instructions.
  • Page 76 LITERATURE: 0844 892 9800 TRAINING: 01905 752526 SALES: 01905 752640 Worcester, Bosch Group Cotswold Way, Warndon, Worcester WR4 9SW. Tel. 0844 892 9900 Worcester, Bosch Group is a brand name of Bosch Thermotechnology Ltd. worcester-bosch.co.uk 6 720 644 741a (2010/10)

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Greenstar 28i junior

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