Worcester GREENSTAR 24i Junior Installation, Commissioning And Servicing Instructions
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Worcester GREENSTAR 24i Junior Installation, Commissioning And Servicing Instructions

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INSTALLATION, COMMISSIONING AND SERVICING INSTRUCTIONS
WALL HUNG RSF GAS FIRED CONDENSING COMBINATION BOILER
GREENSTAR 24i Junior/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
24i Junior
47-406-54
28i Junior
47-406-56
24i Junior
47-406-55
28i Junior
47-406-57

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  • Page 1 INSTALLATION, COMMISSIONING AND SERVICING INSTRUCTIONS WALL HUNG RSF GAS FIRED CONDENSING COMBINATION BOILER GREENSTAR 24i Junior/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 5.5.3 Domestic hot water: ......33 KEY TO SYMBOLS AND SAFETY PRECAUTIONS ... . 3 Finishing commissioning .

  • Page 3: Key To Symbols And Safety Precautions

    Keywords at the start of a warning indicate the type and prosecution. seriousness of the ensuing risk if measures to prevent If you are in any doubt, contact the Worcester Technical helpline the risk are not taken. (0844 892 3366).
  • Page 4 KEY TO SYMBOLS AND SAFETY PRECAUTIONS BS5440:1 Flues and ventilation for gas appliances of rated heating not exceeding 70kW (net): Flues Benchmark places BS5440:2 Flues and ventilation for gas appliances of rated heating not responsibilities on both exceeding 70kW (net.: Air Supply manufacturers and BS7593 Treatment of water in domestic hot water central heating installers.

  • Page 5: Appliance Information

    APPLIANCE INFORMATION APPLIANCE INFORMATION APPLIANCE Depth to wall 330mm (When fitted to wall frame) 700mm* 400mm * 710mm to top of case front 6720643895-01.3Wo 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 6: 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 Minimum DHW flow rate to activate the boiler...

  • Page 7: Layout

    APPLIANCE INFORMATION LAYOUT Fig. 1 Main boiler components 6 720 802 047 (2013/05)
  • Page 8 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 Manual vent point Silicon tube - heat exchanger air vent Fan pressure test point...

  • Page 9: Pre-Installation

    PRE-INSTALLATION 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 22mm & isolator Reset button DHW connection System pressure gauge CH flow isolator ECO button Condensate connection...

  • Page 10: Mains Supply

    ▶ In cases where all attempts to find a micro leak have the mains water supply can cause a pressure build up failed, Worcester, Bosch Group supports the use of which could damage the boiler and other household Fernox F4 leak sealer.

  • Page 11: Condensate Pipe Work

    PRE-INSTALLATION NEW BUILD - SEALED SYSTEM WITH ZONE VALVES The boiler is equipped with an internal by-pass. The latest Part L1a regulation for new installations require separate zone The internal bypass is not intended to be a substitute for controls for the central heating. an external system bypass.

  • Page 12: External Connections

    PRE-INSTALLATION 75mm min. 22mm Ø 22mm Ø Fig. 7 Disposal to soil vent stack Alternatively if the first option is not possible an internal kitchen or 6720644744-08.2Wo bathroom waste pipe, washing machine waste pipe etc. can be used. Fig. 9 Condensate pump disposal Ensure that the condensate drain pipe is connected “down stream”...
  • Page 13 PRE-INSTALLATION ▶ The use of fittings, elbows etc. should be kept to a minimum and any CONDENSATE SOAK AWAY internal “burrs” on cut pipe work should be removed so that the • The condensate drainage pipe may be run above or below the ground internal pipe section is as smooth as possible.

  • Page 14: Pressure Relief Pipe Work

    PRE-INSTALLATION PRESSURE RELIEF PIPE WORK Vent position To room or internal space Direct to outside High level Minimum free area 122cm Min. free area 61cm NOTICE: Low level Minimum free area 122cm Min. free area 61cm ▶ The pressure relief valve is a safety device for the boiler and if activated may discharge boiling water or Table 8 Compartment ventilation steam through the relief valve drain pipe.

  • Page 15: Bathrooms

    PRE-INSTALLATION PLUMBING MANIFOLD If Side Clearances are Reduced (millimetres) If total side clearance is Increase height or Front clearance 3.7.1 CONNECTIONS reduced to: clearances to (approx): (to removable Heating System 22mm compression fittings (Combined left & right (Combined top & door) must be clearances excluding bottom clearances...

  • Page 16: Flue Options

    PRE-INSTALLATION FLUE OPTIONS 1 2 3 CAUTION: Non accessible flue systems: ▶ Where a flue system is not going to be accessible, provision must be made for service and inspection. ▶ Voids containing concealed flues must have at least one inspection hatch no less than 300mm square. ▶...
  • Page 17 PRE-INSTALLATION 350 mm - 570 mm 130 mm Min 500 mm 300 mm Flat roof 6720643895-12.1Wo 6 720 802 047 (2013/05)

  • Page 18: Flue Terminal Positions

    PRE-INSTALLATION FLUE TERMINAL POSITIONS All measurements in millimetres 52mm 104mm 1,500 1,500 300 300 300 300 1,200 Boundary Line Fig. 19 Flue terminal positions NOTICE: ▶ All measurements are the minimum clearances required. ▶ Terminals must be positioned so to avoid combustion products entering the building. ▶...

  • Page 19: Plume Management Terminal Positions

    PRE-INSTALLATION 3.10 PLUME MANAGEMENT TERMINAL POSITIONS All measurements in millimetres Flue terminal guard 7 716 191 176 ±45° Plume re-direction: 180° Flue Exhaust Outlet 1,500 Air Intake ±80° 1,200 Boundary Line Fig. 20 Plume terminal positions Maximum and minimum plume management lengths: ▶...

  • Page 20: Installation

    INSTALLATION Additional requirements for roof space installation: INSTALLATION • The boiler should be first unpacked before ascending ladder to loft space. WARNING: All the previous “Pre-Installation” sections • Two sets of steps should be used. must be read and the requirements met before starting •...

  • Page 21: Unpacking The Appliance

    INSTALLATION 6720643895-18.1Wo Fig. 23 Remove outer carton Fig. 22 Marking the flue position UNPACKING THE APPLIANCE 1. Outer carton 2. Inner sleeve (unwrap from front) 3. Packing base 4. Protective wrapping 5. Appliance outer case ▶ Remove outer carton (1) and place safely away from the working area. ▶...

  • Page 22: Boiler Connections

    INSTALLATION PREPARING THE WALLFRAME If using the optional filling loop: 7 716 192 281 (not supplied with the boiler) fit it before hanging the boiler on the wall frame. The bonded washer supplied is for the Gas connection only. ▶ Fit sealing washers to service valves before hanging boiler. Fig.
  • Page 23 INSTALLATION HANGING THE BOILER ▶ Make connections to the heating system. Connect the gas supply to the boiler gas cock 22mm compression. CAUTION: Hanging the boiler Connect mains water in and DHW out. ▶ Remove the plastic strip fitted to pipes before EXPANSION VESSEL CONNECTION hanging the boiler.

  • Page 24: 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 before securing For vertical flues and 80/125mm horizontal flues, please refer to the flue section to the turret. separate instructions supplied with the flue kit. To ease assembly of flue components, apply silicone The flue terminal MUST be fitted with the 'TOP' label uppermost to allow lubricant to sealing surfaces.

  • Page 25: Installing The Telescopic Flue

    INSTALLATION 4.5.3 INSTALLING THE TELESCOPIC FLUE Refer to figure 38. 1. Set the flue length to the distance required, secure with screws provided. 2. Seal the joint with the aluminium tape provided. 3. Slide the inner wall seal onto the terminal. 4.

  • Page 26: Condensate Connection

    INSTALLATION CONDENSATE CONNECTION Never terminate or discharge into any open source, including; sink, bath, shower, bidet, toilet etc. NOTICE: Any external condensate pipe work must be protected with weather resistant insulation to help prevent freezing. • Ensure that the condensate drain is a 22mm diameter plastic pipe. The pipe must fall at least 50mm per metre towards the outlet.

  • Page 27: Electrical

    INSTALLATION ACCESS TO ELECTRICAL CONNECTIONS: ▶ Remove boiler casing to access control panel. Refer to figure 48. 1. Remove the screw securing the control panel. 2. Lower the control panel into the horizontal service position. Fig. 48 Moving control panel into the service position 6720643895-37.2Wo When stripping wires always ensure copper strands do Fig.

  • Page 28: Mounting Optional Plug-In Controls

    Figures 54 and 55 give some suggestions regarding zoning the system for a small dwelling, less than 150m floor area, using a third party programmer or a Worcester programmer. THIRD PARTY EXTERNAL TIMER AND TWO ZONES Zone 1 Zone Valve Fig.
  • Page 29 The programmable thermostat may be a hard wired or RF type. This diagram is applicable for the hard wired unit and the receiver section of the RF pack. Plug in Worcester timer. (see timer operating Programmable 230V instructions for Thermostat...

  • Page 30: Commissioning

    COMMISSIONING OPTIONAL EXTERNAL FROST STAT CONNECTION ST6: Frost Thermostat NP LP 6720643895-43.1Wo Fig. 59 Frost Thermostat ▶ Connect frost thermostat cables to terminals F & F ▶ These are not polarity sensitive. ▶ The external frost thermostat only operates the pump (see page 58 for internal frost protection).

  • Page 31: Filling The System

    ▶ In cases where all attempts to find a micro leak have to a static head of 7.5m (22ft). A Schraeder type valve is fitted to the failed, Worcester, Bosch Group supports the use of expansion vessel to allow for pressure adjustment if required.

  • Page 32: Starting The Appliance

    COMMISSIONING STARTING THE APPLIANCE Having checked: CAUTION: RUNNING THE APPLIANCE ▶ That the boiler has been installed in accordance with the installation ▶ Never run the appliance when the appliance/system is instructions. empty or partially filled. ▶ The integrity of the flue system and flue seals, as described in section 6.3 of this manual.

  • Page 33: Checking The Gas Rate

    COMMISSIONING 5.5.3 DOMESTIC HOT WATER: Meter Gas Control Natural Gas valve Controlling the hot water temperature: < 2.5mbar The hot water temperature can be set to between 40 an 60 °C using the difference DHW temperature control. DOMESTIC HOT WATER PRE-HEAT: Pre-heat reduces the time taken to produce hot water at the tap and is 19 - 23 mbar controlled by the ECO button.

  • Page 34: Installing Bottom Panel

    SERVICE AND SPARES 5.6.3 INSTALLING BOTTOM PANEL • To ensure the continued efficient operation of the appliance it must be checked at regular intervals. ▶ The bottom panel slides onto two ledges either side of the boiler • The frequency of servicing will depend upon the particular installation frame.

  • Page 35: Check The Gas Inlet Pressure

    SERVICE AND SPARES Regulator Gas Control L.P.G. valve < 4.0mbar difference 32 - 45 mbar 28 - 41 mbar Boiler inlet 2.5 mbar 1.5 mbar drop drop Fig. 72 Control panel into service position 29.5 - 42.5 mbar 6720644744-45.2Wo CHECK THE GAS INLET PRESSURE Fig.

  • Page 36: Fan Pressure Test

    SERVICE AND SPARES FAN PRESSURE Fig. 76 Flue integrity test Fig. 78 Fan pressure test point FAN PRESSURE TEST ▶ Remove the cover and connect a digital manometer to the fan pressure test point. This test is to determine if the heat cell requires ▶...

  • Page 37: Flue Gas Analysis

    SERVICE AND SPARES SETTING THE AIR/GAS RATIO NOTICE: THE SETTING OF THE GAS RATIO MUST BE CARRIED OUT BY A COMPETENT PERSON. SETTING OF THE GAS RATIO MUST NOT BE ATTEMPTED UNLESS THE PERSON CARRYING OUT THE TEST IS EQUIPPED WITH A COMBUSTION ANALYSER CONFORMING TO BS 7927 AND IS COMPETENT IN ITS USE.

  • Page 38: Cleaning The Heat Exchanger

    SERVICE AND SPARES 2.5 mm 4 mm 6720643895-72.1Wo Fig. 84 Gas valve connection 6720643895-66.1Wo Fig. 83 Gas valve adjustment ▶ Remove electrical connector and earth wire from fan. CO/CO settings for Greenstar i Junior To prevent damage to the electrodes when removing the CO/CO should be measured after 10 minutes.
  • Page 39 SERVICE AND SPARES BURNER REMOVAL Refer to figure 87 1. Remove clamping plate. 2. Remove spark/flame electrode assembly and seal from the top of the heat exchanger. 3. Remove burner. Fig. 87 Burner removal Checking and cleaning the electrode assembly: NOTICE: Cleaning ▶...

  • Page 40: Replacement Of Parts

    SERVICE AND SPARES ▶ Clean heat exchanger flue ways using the cleaning brush removing any CLEANING THE SYPHON debris from the access point in the sump. There is no need to remove the Syphon to clean. ▶ Clean around the sealing surface on the sump. To drain debris from the syphon, release the clips and remove the ▶...

  • Page 41: Primary Sensor (Ch Ntc)

    SERVICE AND SPARES 6.8.2 PRIMARY SENSOR (CH NTC) ▶ Remove electrical connections. ▶ Push the flue limit thermostat in from the sump. Refer to figure 92 for removal. ▶ Retrieve the thermostat from the sump well. 1. Remove electrical connection by pulling upwards. Squeeze retaining clip on plastic moulding of sensor and pull back and up until clear of pocket in heat exchanger.

  • Page 42: Gas Valve

    SERVICE AND SPARES 6.8.6 GAS VALVE NOTICE: Refer to figure 96 ▶ If the joint between the Air/Gas manifold and heat ▶ Isolate gas supply at boiler gas cock. exchanger is disturbed the sealing gasket must be 1. Remove wire clip from gas valve outlet. replaced.

  • Page 43: Fan

    SERVICE AND SPARES 6.8.8 FAN 6.8.9 ELECTRODE ASSEMBLY AND BURNER Remove the air/gas manifold as described in the previous section. Refer to figure 102. ▶ Disconnect spark electrodes and flame sensor connection. 1. Remove two screws retaining the fan to the air/gas manifold. ▶...

  • Page 44: Heat Exchanger

    SERVICE AND SPARES Fig. 105 Clamping plate secured 6.8.11 HEAT EXCHANGER ▶ Isolate flow and return valves then drain the boiler. ▶ Remove syphon. ▶ Remove the air/gas manifold and fan. Refer to figure 106. 1. Remove the clip from plastic elbow on the flow pipe. 2.

  • Page 45: Access To Boiler Control Components

    SERVICE AND SPARES Refer to figure 108. ▶ Reassemble and check combustion as stated in the gas conversion section. 6.6. 1. Release the clip. 2. Move the lower exhaust connector up NOTICE: CO/CO CHECKS ▶ Remove the complete exhaust assembly. ▶...

  • Page 46: Access To Pcb

    SERVICE AND SPARES 6.8.14 ACCESS TO PCB 2. Remove the front fascia. Refer to figure 114 and disconnect all electrical connections from the control. 1. Remove five screws retaining the rear panel of the control. 2. Remove the rear panel. Fig.

  • Page 47: Syphon Removal

    SERVICE AND SPARES 6.8.16 SYPHON REMOVAL 6.8.18 DIVERTER VALVE Removal of the syphon assembly will give access to the To ease assembly of components, apply silicone Auto Air Vent. lubricant to sealing surfaces. To release the syphon from the sump: ▶...

  • Page 48: Dhw Temperature Sensor

    SERVICE AND SPARES 6.8.20 DHW TEMPERATURE SENSOR 6.8.22 FLOW SENSOR, FLOW RESTRICTOR HOUSING AND FILTER ▶ Ensure the domestic hot water circuit is fully drained. ▶ Ensure the domestic hot water circuit is fully drained. ▶ Disconnect the electrical connection from the sensor. ▶...

  • Page 49: Drain Tap

    SERVICE AND SPARES 6.8.24 DRAIN TAP 1. Release the locking devices that secure the two copper water pipes leading to the combustion chamber by squeezing the two tabs ▶ Ensure the appliance has been fully drained. together and rotating anti-clockwise (viewed from above). 1.

  • Page 50: Ch Pressure Relief Valve

    SERVICE AND SPARES 6.8.27 CH PRESSURE RELIEF VALVE 6.8.29 DHW PLATE HEAT EXCHANGER ▶ Remove the hydraulic block from the boiler (See 6.8.26 Removing Remove the Hydraulic block from the boiler (See 6.8.26 the Hydraulic Block). removing the Hydraulic Block). 1.

  • Page 51: Expansion Vessel

    SERVICE AND SPARES 6.8.31 EXPANSION VESSEL The expansion vessel can be replaced with the boiler in position if there is a side exit flue fitted and a minimum clearance of 340mm above the boiler casing. If a vertical flue is fitted then a similar clearance to one side of the flue is required.

  • Page 52: Short Parts List

    SERVICE AND SPARES SHORT PARTS LIST Burner Gas Valve 8 716 116 067 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 (including HT3 BUS enabled thermostat...

  • Page 53: Fault Finding And Diagnosis

    FAULT FINDING AND DIAGNOSIS FAULT FINDING This fault finding information is for guidance only. Worcester cannot be held responsible for costs incurred by persons not deemed to be competent. The electronic control system for this boiler incorporates a blue central indicator. This normally confirms the permanent mains supply but, by flashing at different rates during a fault, provides a guide to the cause as listed.This fault finding system assumes that the appliance has been operating normally...
  • Page 54 FAULT FINDING AND DIAGNOSIS Blue light Lockout reset indication button Fault Possible solution/check Slow flash Flashing (reset Ignition lockout ▶ Gas present and at correct pressure? (mostly off, required) ▶ Gas valve flashes on) – Check that there is 35V d.c. to each solenoid –...

  • Page 55: Circuit Diagram

    ST17 Yellow Green Black Blue EMS BUS contacts Blue Purple (for FX controls) Purple Orange Orange WORCESTER 24V CONTROLS OPTION, PLUG IN POINT Green (under blanking cover on fascia) Black 230V~ Yellow Yellow Yellow PRE WIRED LINK ST18 DIAGNOSTIC 6720804530-09.2Wo...

  • Page 56: Central Heating Function

    FAULT FINDING AND DIAGNOSIS CENTRAL HEATING FUNCTION Fig. 136 CH function 6 720 802 047 (2013/05)

  • Page 57: Preheat And Dhw Function

    FAULT FINDING AND DIAGNOSIS PREHEAT AND DHW FUNCTION Fig. 137 Pre-heat and DHW 6 720 802 047 (2013/05)

  • Page 58: 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) Internal boiler Central heating...
  • Page 59 NOTES 6 720 802 047 (2013/05)
  • Page 60 6 720 802 047 (2013/05)
  • Page 61 6 720 802 047 (2013/05)
  • Page 62 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 63: 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 64 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 Document No. 6 720 802 047 (2013/05)

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