1. DL manuals
  2. Worcester
  3. Boiler
  4. 24ijunior
  5. Installation and servicing instructions

Worcester 24ijunior Installation and servicing instructions

Manual is about: WALL MOUNTED COMBINATION BOILERS FOR CENTRAL HEATING AND MAINS FED DOMESTIC HOT WATER

Summary of 24ijunior

  • Page 1

    24i / 28i jju un niio orr wall mounted combination boilers for central heating and mains fed domestic hot water installation and servicing instructions this appliance is for use with natural gas or lpg (cat ii 2h3p type c12 & c32) 24i gc number 47 311 69 (n.G.) gc number 47 311 71 (l.P.G.) 28i gc nu...

  • Page 2

    The appliance is suitable for installation in gb and ie only and should be installed in accordance with the rules in force. 1.1 gas safety (installation & use) regulations 1998: it is the law in gb that a competent person in accordance with the above regulations installs all gas appliances. Failure ...

  • Page 3

    2.3 electrical supply 230v - 50hz. Load 152 watts. External fuse 3a, internal fuses f1 - 2a, f2 - 1.25a (20mm). 2.4 gas supply the appliances require a maximum of 3.17 m 3 /h of natural gas (g20) or 1.23 m 3 /h of propane (g31) [28i] or 2.74 m 3 /h of natural gas (g20) or 1.06 m 3 /h of propane (g31...

  • Page 4

    4 fig. 2. Water flow diagram. 7 6 1. Ch flow 8. Expansion vessel 2. Domestic hot water flow 9. Primary heat exchanger 3. Mains cold water inlet 10. Expansion vessel charge point 4. Ch return 11. Relief valve 5. Pressure relief valve discharge 12. Boiler drain point 6. Domestic water flow turbine 13....

  • Page 5

    5 3. Technical data maximum available pump head boiler output head min. Flow rate kw metres l/min. °c 8 4.5 10.4 11 23.5 2.2 18.3 18 27.5 2.0 18.3 21 table 3 mechanical specifications 24i 28i central heating flow - compression 22mm 22mm return - compression 22mm 22mm cold water inlet - compression 1...

  • Page 6

    Performance specifications 24i 28i primary water capacity litres 3 3 ip rating (whole of boiler) ip 20 ip 20 maximum mains inlet pressure bar 10 10 minimum mains inlet pressure (working) for maximum flow bar 0.9 0.9 minimum mains inlet pressure (working) for operation bar 0.1 0.1 domestic hot water ...

  • Page 7

    Fig. 4. Appliance casing dimensions and required clearances (side view). All dimensions in mm 24i 28i a ch flow = 70 90 b relief valve discharge = 88 108 c dhw outlet = 135 155 d gas = 200 220 e cold water inlet = 265 285 f ch return = 330 350 fig. 3. Appliance casing dimensions and required clearan...

  • Page 8

    The appliance may be installed in any room but refer to the requirements of the current iee regulations and, in scotland, the relevant electrical provisions of the building regulations with respect to the installation of appliances in rooms containing baths or showers. In eire refer to the etci rule...

  • Page 9

    6.1 a separate vent for combustion air is not required. Refer to bs5440:2. The system must comply with requirements of bs6798 and bs5449 and, in eire, the current edition of is813. It must not be operated without being full of water and correctly pressurised. The pressure relief valve will operate a...

  • Page 10

    It may be necessary to contact the local water company before connecting the appliance. Where back-flow prevention devices, including water meters, are fitted the expansion of hot water into cold water main can be prevented. This can result in a pressure build-up that may cause damage to the boiler ...

  • Page 11

    11 fig. 9. Wiring diagram. Control board fan flame sense electrode spark electrode spark generator mains in link black 6.3mm tag common white 4.8mm tag low speed red 2.8mm tag high speed flow turbine st16 2 blue 2 orange 2 brown br own blue blue br own green 2 red 2 yellow st2 st15 st1 pump gas valv...

  • Page 12

    12 fig. 10. Functional flow diagram. On/off swit ch st2 (l s ) st2 (l r ) st2 (n s ) st1 centr e pin st15 right pin pump fan st2 pin n optional link r oom thermost at tr ansf ormer fuse f2 (1.25a slow) fuse f1 (2a slow) n n st2 pin l live in electronics electronics inputs outputs spark indicat or s ...

  • Page 13

    Note: read this section fully before commencing the installation. 11.1 general the appliance is only suitable for fitting to a sealed system. The flue must be installed as specified in bs5440:1 and the current building regulations, and, in eire in accordance with the current edition of is813. 11.2 u...

  • Page 14

    11.7 install the boiler check that the gas and water valves are closed. Refer to fig 13. Fit the fibre washers, in the hardware pack, to the service valves on the manifold. Remove the two fixing screws. Lift the appliance to the wall, engage in the top support and lower onto the manifold assembly. T...

  • Page 15

    11.8 air and flue duct preparation 11.8.1 the method of installation of the flue system may be varied to suit the actual site conditions. The instructions for connecting and fixing the ducts must, however, be strictly followed. Remove all packing material from the flue components. 11.8.2 11.8.3 fit ...

  • Page 16

    11.9 measure and cut the ducts. General: cut the ducts as necessary, ensuring that the cuts are square and free from burrs. Always check the dimensions before cutting. Measure the distance l. Refer to fig. 20, 21, 22 and 23. The standard flue can be telescopically adjusted to any length between 425m...

  • Page 17

    11.11 fitting of the flue assembly without access to the terminal. The rubber gasket kit is available from worcester heat systems. Note: a larger diameter (150mm) opening in the wall is required. Refer to table 2. Prepare the flue assembly as described in section 11.8. Fit the rubber sealing gasket ...

  • Page 18

    If z is between 425 - 725mm it is not necessary to cut the terminal assembly or use a second extension duct as the length can be set telescopically. If z is greater than 725mm then two extension duct assemblies will be required, the first assembly being cut to length as plain tubes. If more than two...

  • Page 19

    Neutr al 19 fig 31 - mains voltage external controls connections 230 v room thermostat connections ns ls l r st2 ns ls l r st2 remove link liv e swit ched liv e neutr al liv e swit ched liv e motor 230 v programmer connections 230 v room thermostat and programmer connections ns ls l r neutr al liv e...

  • Page 20

    In eire additional guidance on commissioning is contained in paragraph 15 of is 813:2001 13.1 water treatment: for optimum performance after installation, this boiler and its associated central heating system should be flushed in accordance with the guidelines given in bs7593 – treatment of water in...

  • Page 21

    13.7 checking the burner pressure unscrew the facia fixing screw. Unhook the panel and lower it into the bottom support lugs. Do not strain the support strap. Refer to fig. 18. Check that the gas and electricity supplies are turned off. Connect pressure gauges to the gas valve to measure the inlet p...

  • Page 22

    Hand over the user booklet and the completed benchmark logbook and/or, in eire, the declaration . Explain how to operate the appliance safely and efficiently. Tell the user what to do if the appliance is not to be used in very cold conditions. Tell the user what to do if the system pressure falls. E...

  • Page 23

    23 fig. 41. Inner case components 1. Flue hood 2. Overheat thermostat 3. Burner 4. Combustion chamber cover 5. Spark electrode assembly 6. Heat exchanger 6 1 4 5 2 7 11 3 8 9 7. Fan assembly 8. Air pressure switch 9. Flue gas sampling point 10. Combustion chamber cover fixing screws 11. Pump connect...

  • Page 24

    Inner case cover unscrew the two screws and lift off. Refer to fig. 39. Combustion chamber cover unscrew the two screws, lift and pull forward to remove. Refer to fig. 41. Fan carefully pull off the electrical connections and the tubes from the airflow-sensing device. Unscrew the three screws and re...

  • Page 25

    Important: turn off the gas supply and electrically isolate the appliance before replacing any components. Note: turning the control knob fully anti-clockwise does not isolate the appliance electrically. After the replacement of any components always check for gas soundness where relevant and carry ...

  • Page 26

    2 spark electrode remove the inner casing cover and the combustion chamber cover. Carefully pull off the lead from the electrode. Unscrew the screw and remove the assembly. Refer to fig. 48. Ensure that the electrode is at the correct height above the burner blade. 3 flame sense electrode remove the...

  • Page 27

    5 combustion chamber insulation. Remove inner casing door and combustion chamber cover. Slide the damaged insulation panel from the appliance rear remove heat exchanger. Refer to fig 61. Remove the side insulation panels. Slide the rear insulation forward and up to remove. Replacement is the reverse...

  • Page 28

    9 inlet water filter and flow restrictor remove the flow turbine as described in 16.8 preceding. Taking care, remove flow restrictor assembly from the flow turbine. Carefully clean wire mesh by back flushing with water or replace assembly if necessary. Refer to fig. 55. 10 control board check that t...

  • Page 29

    15 primary [ch] sensor remove the clip-on facia cover and the cabinet. Lower the facia onto the support lugs. Carefully pull-off the connections. Release the clip and remove the sensor. Refer to fig. 58. Do not omit the heat transfer paste when fitting the replacement sensor. 16 primary overheat the...

  • Page 30

    20 auto air vent remove the complete pump assembly as described in section 16.18. Take care not to strain the electrical connections. Pull out the clip securing the auto air vent cartridge. Refer to fig 52. Do not omit the o-ring when fitting the new cartridge. Refit the pump assembly as described i...

  • Page 31

    1 h05-333 burner 24 ng 1 8 716 105 484 0 2 h05-352 burner 28 ng 1 8 716 105 485 0 3 h05-337 gas valve ng 1 8 716 105 654 0 4 h05-338 gas valve lpg 1 8 716 105 650 0 5 e80-454 air pressure switch 1 8 747 004 461 0 6 e94-710 e lectrode spark 1 8 716 105 186 0 7 e01-612 e lectrode flamesense 1 8 716 12...

  • Page 32

    32 1 - 2 3-4 9 10 28 12 -13 14 -15 16 19 20 11 18 24 8 5 27 6 7 17 25-26 21-23.

  • Page 33

    Room thermostat and/or mains programmer (or link) on facia programmer (if fitted) on ch control knob on 33 18. Operational flow diagrams main switch on central heating demand pump on. Fan on/ ignition sequence. Burner light on. Three minute wait gas valve off. Burner light off. (pump still on) over ...

  • Page 34

    Commence normal central heating mode until temperature reaches 20°c 34 there is a delay of 6 seconds, pump pulses for 2 seconds, 60 second wait, 2 second pump pulse, 60 second wait, pump pulses for 2 seconds. Overrun function run pump end dhw demand end ch demand pump runs for 3 minutes autofrostat ...

  • Page 35

    Note: this fault-finding information is for guidance only. Worcester heat systems cannot be held responsible for costs incurred by persons not deemed to be competent. By flashing at various rates, the oval shaped facia light will indicate specific fault conditions. If this is used with other observa...

  • Page 36

    36 is there a 230v ac live supply across terminal st2 pins l and n? Switch off electrical power. Has fuse f1 blown? Replace fuse and investigate cause. Suggestions: cable damage, connections to (or faults within) pump, fan, external 230v controls, transformer or board. Check electrical supply to boi...

  • Page 37

    37 re-connect the 3-way connector and open a tap to run the turbine. Is there between 1.5v and 4.5v across the green 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)...

  • Page 38

    38 is the boiler fully water pressurised and is all air vented? Rectify fault. No no no reset and restart the boiler in ch mode. Does the pump run? Yes test resistance across pins 4 and 5 (blue wires). Is resistance between 10Ω and 25Ω ? Repair or replace harness. Remove front panel. Reset and resta...

  • Page 39

    39 remove combustion chamber cover. Is the sense electrode and lead in good condition and is gap correct? Replace flame sensor or wiring. No no remove multiway connector from board position st16. Is there continuity from pin 10 (white wire) to flame sensor? Yes yes yes relace control board. Note: it...

  • Page 40

    40 remove multiway connector from board position st16. Test resistance across pins 16 and 17 ( yellow wire). Is it between 1 kohm and 30 kohm? Test resistance across contacts 12 and 13 (red wire). Is it between 1 kohm and 30 kohm? Is there continuity from individual pins 16 and 17 to dhw sensor? Che...

  • Page 41

    41 replace control board. In the unlikely event of this not solving the problem replace code plug. Pressure switch has opened during operation. Check flue for blockage. Also investigate sense tubes and pressure switch. Replace fan connector st1. Remove electrical connectors from air pressure switch ...

  • Page 42

    42 boiler is running in “autofrost stat” mode. See section 17. Replace control board. Note: a damp board could cause this fault. Is the boiler in a very cold environment (less than 5°c)? Test g no yes does the problem occur in ch mode only? Test i no yes it is not possible to easily isolate the faul...

  • Page 43

    43 20. Conversion instructions nominal boiler ratings (10 minutes after lighting) boiler adjusted for g20 (natural gas) output input (net) gas rate kw kw m bar. M 3 /h 8.0 9.5 1.2 1.00 27.5 30.0 14.7 3.17 boiler adjusted for g31 (propane) 8.0 9.5 3.4 0.39 27.5 30.0 35.3 1.23 table 1. 28i burner pres...

  • Page 44

    This booklet is accurate at the date of printing but will be superseded and should be disregarded if specifications and/or appearances are changed in the interests of continued improvement. All goods sold are subject to our official conditions of sale, a copy of which may be obtained on application....