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3

B029

1.

SERVICING 

INSTRUCTIONS

The life of individual components vary and they will need servicing or
replacing as and when faults develop.
The fault finding sequence chart in chapter 2 will help to locate which
component is the cause of any malfunction, and instructions for removal,
inspection and replacement of the individual parts are given in the following
pages.

1.1

Replacement
of Parts

1.2

To Gain General
Access

All testing and maintenance operations on the boiler require the control panel
to be lowered. This will also require the removal of the casing.

To dismantle the front part of the casing, proceed as follows:
1. 
Remove screw “A” (see fig. 1.1);
2. Lift the front panel up and forward (see fig. 1.2).

A

Fig. 1.2

Fig. 1.1

To ensure efficient safe operation, it is recommended that the boiler is
serviced annually by a competent person.

Before starting any servicing work, ensure both the gas and electrical
supplies to the boiler are isolated and the boiler is cool.
Before and after servicing, a combustion analysis should be made via the flue
sampling point (please refer to the Installation Manual for further details).

After servicing, preliminary electrical system checks must be carried out to
ensure electrical safety (i.e. polarity, earth continuity, resistance to earth and
short circuit).

Summary of Contents for EURO COMBI A/23 MFFI

Page 1: ...A 23 MFFI A 27 MFFI G C N 47 116 10 47 116 12 Servicing Instructions Type C Boilers LEAVE THESE INSTRUCTIONS ADJACENT TO THE GAS METER...

Page 2: ...or 11 Removing the Gas Valve 12 1 5 Access to the Hydraulic Circuit Removing the D H W Secondary Exchanger 12 Removing the Safety Valve 13 Removing the Automatic Air Vent 13 Removing the Main Flow Cir...

Page 3: ...emoval of the casing To dismantle the front part of the casing proceed as follows 1 Remove screw A see fig 1 1 2 Lift the front panel up and forward see fig 1 2 A Fig 1 2 Fig 1 1 To ensure efficient s...

Page 4: ...ove the screws B 2 Push the two side panels outward slightly fig 1 5 3 Rotate the control panel forward and down Fig 1 4 B Fig 1 5 B C Fig 1 7 Fig 1 6 C To access the areas where the adjustment and co...

Page 5: ...e the injectors using a No 7 socket spanner 5 Replace in reverse order Removing the burner and the injectors 5 B029 Removing the sealed chamber frontal cover 1 3 Access to the Combustion Chamber Remov...

Page 6: ...hilips No 2 star tip screwdriver see fig 1 16 6 Slide the electrode gently downward see fig 1 17 To replace repeat the steps in reverse order paying particular attention to the following a Centre the...

Page 7: ...g 1 21 Use a No 2 star tip screwdriver to remove the switch from the plate Fig 1 21 Fig 1 20 7 B029 1 Drain the boiler of water 2 Release the two connection nuts I connecting the exchanger to the flow...

Page 8: ...the venturi device 1 Disconnect electrical connections and remove screws O using a No 2 star tipped screwdriver see fig 1 24 2 Pull fan to the right forward and remove see fig 1 25 3 Remove fan from...

Page 9: ...9 B029 1 4 Servicing and Removal of the Gas Valve 1 2 3 4 A B C E F D SIT TANDEM SIT SIGMA 1 2 3 4 A B C E F D...

Page 10: ...A page 11 6 When you have completed the above operations turn off the hot water tap re connect the supply terminal to the modureg on the gas valve and replace the cap on the screw of the modureg Sett...

Page 11: ...ors min 13 x 1 25 Gas rate max 3 0 m 106 0 ft Gas rate min 1 2 m 3 h 3 h 42 3 ft 3 h 3 h Inlet pressure 20 mbar 7 8 in w g Burner pressure max 12 3 mbar 4 8 in w g 2 0 mbar 0 8 in w g 13 x 0 72 0 88 m...

Page 12: ...e P C B see the electrical diagrams By adjusting the potentiometer it is possible to change the time interval between the burner shutting down and its next ignition It is preset at 1 minute and can be...

Page 13: ...ator SIT Tandem gas valve 1 Disconnect ignition leads Q1 by pulling upwards see fig 1 30 2 Remove the screws R1 see fig 1 31 with a Pozidrive No 2 star tip screwdriver 3 Remove the spark generator Fig...

Page 14: ...d condition and replace if necessary Important Before any component is removed the boiler must be drained of all water Removing the gas valve 1 Disconnect all the cables from the solenoid and modureg...

Page 15: ...valve Removing the automatic air vent 1 Unscrew valve W see fig 1 39 Removing the main circuit flow switch 1 Remove the cable of the main circuit flow switch Y 2 Remove the screws Y1 see fig 1 40 3 R...

Page 16: ...s A1 and remove the pump see fig 1 42 Removing the pressure gauge 1 Remove the inspection panel see fig 1 6 1 7 2 Release coupling A2 using a 14 mm open ended spanner see fig 1 43 3 Push the pressure...

Page 17: ...Remove the electrical connection from the overheat thermostat see fig 1 48 2 Then remove the thermostat from the pipe by releasing its securing clip Removing the heating temperature sensor N T C 1 Re...

Page 18: ...ove fuse see fig 1 50 1 6 Access to the Control System Removing the time clock 1 Remove the inspection panel see fig 1 6 1 7 2 Remove electrical connection of the clock A5 see fig 1 51 3 Unclip the cl...

Page 19: ...ectors and screws A8 see fig 1 55 8 To remove the 240V P C B remove the electrical plug connectors and screws A9 see fig 1 56 9 Replace either P C B in reverse order Fig 1 53 Fig 1 54 Fig 1 55 Fig 1 5...

Page 20: ...d outlet 3 Check replacethepower supplyPCB Pressthe On Off Button FOR BOILERS EQUIPPED WITHAN ELECTRONIC ANT FREEZE SYSTEM HAS THE SAFETY BEEN TRIGGERED TO ACTIVATE THE DEVICE T sensor 5 C FOR BOILERS...

Page 21: ...n the system 2 Checkthepressureswitch foractivatingpump 3 Check replacewater gaugeandrefill the thesystemproperly 1 Turn theboileroff andthen backon again safetyreset 1 Checkto seeifpumpis stuck 2 Rep...

Page 22: ...lacepower supplyPCB 5 Check replacecontrol PCB 1 pressureswitch wiring 2 Checkwhetherreset button isstuck 3 detection electrode Check replaceair Check replaceflame 1 2 3 Check replacepower supplyPCB 4...

Page 23: ...ctrode 3 Check thepower PCB 4 Check thecontrol PCB 1 Checksupplyofgasto gas valve 2 CheckpowersupplyPCB 3 Checkcontrol PCB 4 Checkfunctionalityofthe valve Shutdown LEDoff Restartofthefan IS THE AIR PR...

Page 24: ...erflow rate Checkexchangerfordomestic hot water Primaryexchangerisdefective Low waterpressurein heatingsystem Checkgassettingsandregulation Checkforleaksin heatingcircuit Defectivewatersupplyinlet val...

Page 25: ...itch Faulty flame detection Faulty overheat thermostat Faulty exhaust fumes sensor Faulty heating sensor N T C Faulty D H W sensor N T C A b C d E F G I m 1 2 3 4 5 6 2 2 Fault Finding Using the Total...

Page 26: ...Time Clock Connection Q On Off L E D R On Off Switch S Interface Wire for P C B s T Relay Motorised Valve U Ignitor Relay V Gas Valve Relay W Fan Relay X Circulation Pump Relay Y Selector TCS2 Aa Ada...

Page 27: ...27 B029 EX C MI FFI 8 A 23 MFFI A 27 MFFI...

Page 28: ...64 71 75 75 63 65 75 126 72 121 74 10 62 73 80 28 46 45 45 116 54 114 49 50 51 115 113 48 49 52 52 53 47 45 34 33 32 35 29 30 103 27 117 5 96 102 100 101 100 41 39 97 108 14 37 39 34 38 29 41 40 43 4...

Page 29: ...way main flow group Gasket 1 2 Manual vent cock Safety valve 3 bar 1 2 Pressure gauge Time clock P C B EX C MI FFI P C B EI A MFFI P C B cable Fan Fan Fan inlet gasket Venturi exhaust manifold header...

Page 30: ...3 way main flow group Gasket 1 2 Manual vent cock Safety valve 3 bar 1 2 Pressure gauge Time clock P C B EX C MI FFI P C B EI A MFFI P C B cable Fan Fan Fan inlet gasket Venturi exhaust manifold heade...

Page 31: ...or 3 way main flow group Gasket 1 2 Manual vent cock Safety valve 3 bar 1 2 Pressure gauge Time clock P C B EX C MI FFI P C B EI A MFFI P C B cable Fan Fan Fan inlet gasket Venturi exhaust manifold he...

Page 32: ...ri SpA Italy Commercial subsidiary MTS GB LIMITED MTS Building Hughenden Avenue High Wycombe Bucks HP13 5FT Telephone 01494 755600 Fax 01494 459775 Technical Service Hotline 01494 539579 23 99 84 1268...

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