Biasi 24S Service Manual
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Biasi 24S Service Manual

Biasi 24S Service Manual

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SERVICE MANUAL
Models covered by these instructions
24S
28S
24SR
Wall hung, fan flue, room sealed gas boiler
Leave this manual adjacent to the gas meter
Biasi U.K. Ltd
Unit 32/33, Planetary Road
Industrial Estate, Neachells Lane
Willenhall, Wolverhampton WV 13 3XB
Tel: 01902 304 400

Table of contents

1
1.1
1.2
2
2.1
2.2
2.3
2.4
2.5
2.6
2.7
3
3.1
3.2
3.3
3.4
4
5
5.1
5.2
5.3
6
6.1
6.2
7
7.1
7.2
7.3
8
8.1
8.2
8.3
9
9.1
9.2
9.3
9.4
9.5
9.6
9.7
9.8
9.9
Thermal control in the "winter" mode
9.10
Thermal control in the "summer" mode
10
10.1
10.2
10.3
10.4
11
(47 970 06)
(47 970 07)
(41 970 03)

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Summary of Contents for Biasi 24S

  • Page 1: Table Of Contents

    Access to the electric parts of the control panel Access to the sealed chamber Emptying the main circuit Emptying the d.h.w. circuit Diagrams Wiring diagram (24S 28S) Wiring diagram (24SR) Functional flow diagrams Control circuit voltages Fault finding Main heat exchanger...

  • Page 2: Overall Information

    11.1 Function 11.2 Nomenclature of the parts 11.3 Adjustment 11.4 Checks 11.5 Removal Main circuit flow switch 12.1 Function 12.2 Checks 12.3 Removal D.h.w. filter and flow limiter 13.1 General notes 13.2 Removal of the filter 13.3 Flow limiter Temperature probes 14.1 Function 14.2...

  • Page 3: General Access And Emptying Hydraulic Circuits

    fig. 2 2 General access and emptying hydraulic circuits 2.1 Nomenclature fig. 3...

  • Page 4: Body Panels

    2.2 Body panels WARNING: isolate the boiler from the mains electricity supply before removing any covering or component. For the most part of the check and maintenance operations it is necessary to remove one or more panels of the body. The side panels can be removed only after the removal of the front panel.

  • Page 5: Control Panel

    To remove the side panels loosen the screws B (fig. 5), bring the base of the panels far from the boiler and lift them, freeing them from the side hooks. fig. 5 To remove the lower protection plate remove the screws “B” (fig.

  • Page 6: Access To The Electric Parts Of The Control Panel

    2.4 Access to the electric parts of the control panel WARNING: isolate the boiler from the mains electricity supply before removing any covering or component. To remove the service panel “5”: Remove the two screws D and remove the service panel (fig.

  • Page 7: Access To The Sealed Chamber

    2.5 Access to the sealed chamber To gain access to the parts contained in the sealed chamber it is necessary to remove the cover of the sealed chamber. For this purpose, remove the front panel of the body, remove the screws G as indicated in fig.

  • Page 8: Emptying The D.h.w. Circuit

    1. Remove the lower protection of the boiler; 2. Close the d.h.w. circuit cut-off valve J (fig. 11); 3. Open one or more hot water taps of the plant until the boiler has been completely emptied. fig. 11 3 Diagrams 3.1 Wiring diagram (24S 28S)

  • Page 9: Wiring Diagram (24Sr)

    3.2 Wiring diagram (24SR)

  • Page 10: Functional Flow Diagrams

    3.3 Functional flow diagrams...

  • Page 12: Control Circuit Voltages

    3.4 Control circuit voltages...

  • Page 13: Fault Finding

    a: never zero (short circuit) never 12V= (open circuit) 4 Fault Finding...

  • Page 16: Main Heat Exchanger

    5 Main heat exchanger 5.1 Characteristics The main heat exchanger (A in fig. 12) has the function of transferring heat of the gas produced by combustion to the water circulating in it. fig. 12 The hydraulic circuit consists of five elliptic pipes connected together in series (fig.

  • Page 17: Removal

    5.2 Removal WARNING: isolate the boiler from the mains electricity supply before removing any covering or component. 1. Empty the main circuit of the boiler 2. Remove the front panel of the body 3. Remove the sealed chamber cover. 4. Remove the cover of the combustion chamber; 5.

  • Page 18: Removal

    The schematic structure is shown in fig. fig. 16 6.2 Removal WARNING: isolate the boiler from the mains electricity supply before removing any covering or component 1. Empty the primary circuit and the d.h.w circuit of the boiler 2. Remove the front panel of the body and lower the instrument panel 3.

  • Page 19: Pump

    Attention. Reassembling the exchanger be sure to put the off center location/securing pin indicated in fig. 18 towards the left side of the boiler. fig. 18 7 Pump 7.1 Function The pump (A in fig. 19) has the function of making the water in the main circuit circulate through the main heat exchanger and therefore through the c/h system (during the c/h function) or through the secondary heat exchanger (during the d.h.w.

  • Page 20: Removal

    Electrical resistance of the windings (at ambient temperature) on switch position 3 must be about: 210 Ω - Myson CP53 180 Ω - Myson CP63 (high head alternative) 220 Ω - Salmson MYE30 120 Ω - Salmson MYL50 (high head alternative) Check the absence of starting defects.

  • Page 21: Checks

    The diverter valve (A in fig. 22) has the function of modifying the hydraulic circuit of the boiler by means of an hydraulic command given by the opening of a d.h.w. tap in order to send the water that exits the main heat exchanger towards the c/h system or towards the d.h.w. heat exchanger. fig.

  • Page 22: Removal

    8.3 Removal WARNING: isolate the boiler from the mains electricity supply before removing any covering or component. Removal of the membrane 1 Remove the front panel of the case, lower the control panel and empty the d.h.w. circuit. 2 Remove the forks C and move away the pipes D. (fig.
  • Page 23 5 Assemble the part proceeding in reverse order. Assembling the part, ensure to place the concave side of the membrane towards the actuator plate I ( fig. 27 When fixing the actuator to the valve, fit the reference shaft J in the seat of the valve ( fig.
  • Page 24 2 Drain the d.h.w. and the c/h circuits. 3 Completely loosen the connections to the hydraulic circuits indicated in fig. 30. fig. 30 4 Remove the forks M and move away the pipes N (fig. 31). fig. 31 5. Remove the forks that hold the d.h.w. pressure switch O and the main circuit flow switch P and separate the switches from the valve (fig.

  • Page 25: Electronic Control Circuit

    The diverter mechanism is composed by two parts. To reach them remove the hydraulic actuator as explained at the step 3 of the part Removal of the membrane of this chapter. With a suitable spanner unscrew both plugs indicated in fig.

  • Page 26: Selection And Adjustment Devices

    9.2 Selection and adjustment devices On the control circuit several selection, adjustment and protection devices are located. (fig. 36). fig. 36...

  • Page 27: Checking The Temperature

    Several of these devices are directly accessible by the user (function switch, temperature adjustment potentiometers etc.) others are accessible by removing the service panel. 9.3 Checking the temperature The control circuit makes it possible to separately adjust the c/h water flow and d.h.w. outlet temperature. The temperature of the water is converted into an electric signal by means of temperature probes.

  • Page 28: Function Selectors

    When the boiler functions in d.h.w. (fig. 38), the signal coming from the d.h.w. temperature probe is compared with the signal given by the instrument panel through the adjustment made by the user (knob fig. 38 Normally, the result of the comparison between these two signals directly operates the adjustment elements of the gas valve, adjusting the useful output generated in order to stabilize the temperature of the exiting water.

  • Page 29: Ignition Gas Pressure Regulator

    fig. 39 the selectors are illustrated in the configuration in which the p.c.b. is set in the factory (natural gas boiler). Selector 2 It selects the functioning of the boiler on the basis of the type of gas used. It allows the selection of the maximum supply current given to the modulator device. To set correctly the selector follow the table of fig.

  • Page 30: Max. C/H Power Regulator

    By using the device “7” (fig. 36) marked “ACC.” on the circuit board, it is possible to adjust the gas pressure at the injectors in the ignition phase. This pressure is maintained at the injectors until ignition occurs (ionization signal). To carry out the adjustment move the function selector n°...

  • Page 31: Thermal Control In The Mode

    3 Delicately flex the hooks indicated in fig. 46 and disconnect the connectors B fig. 46 4 Unscrew the four screws C and remove the circuit (fig. 46); 5 assemble the control circuit following the disassembly procedures in the reverse order. Attention: after having installed the control panel make sure the central heating and domestic hot water temperature adjustment knobs can move...

  • Page 32: Full Sequence Ignition Device

    9.10 Thermal control in the mode fig. 48 10 Full sequence ignition device 10.1 Function The ignition and flame control device, type S4565DD, used on electronic ignition boilers with forced flue gas expulsion carries out the following fundamental functions: does a sequence of operations (ignition cycle) which lead to the ignition of the gas at the burner checks the presence of the flame during the entire period in which it is activated supplies the fan and checks its functioning by means of the signal coming from the flue gas pressure switch.

  • Page 33: Checks

    The ignition device is supplied by the electronic control circuit when the ignition of the burner is requested. The ignition device has a safety function and any incorrect interventions or tampering can result in conditions of dangerous functioning of the boiler. The ignition device can lock the functioning of the boiler (lock state) and stop its functioning up to the resetting intervention.

  • Page 34: Ignition Sequence

    10.4 Ignition sequence fig. 51...

  • Page 35: Gas Valve

    11 Gas valve 11.1 Function...

  • Page 36: Nomenclature Of The Parts

    The gas valve controls the gas inflow to the boiler burner. By means of an electric command given to the on-off operators the passage of the gas through the valve can be opened or closed. By means of an electric command given to the modulating operator the pressure can be varied and therefore the gas flow rate to the burner (modulation).

  • Page 37: Main Circuit Flow Switch

    9. start the boiler; 10. rotate the maximum pressure adjuster “6” until you obtain the espected pressure (by rotating clockwise the pressure increases); 11. turn the boiler off and disconnect the gauge; At the end of the adjustment ensure to seal the gas test point. 11.4 Checks WARNING: isolate the boiler from the mains electricity supply before removing any covering or component.
  • Page 38 12.1 Function The main circuit flow switch (A in fig. 56) is a device that controls the speed of water that crosses the main heat exchanger. fig. 56 This device controls the regular functioning of the pump, the presence of water in the primary circuit of the boiler and the absence of obstructions of the main heat exchanger during the c/h function as well as during the d.h.w.
  • Page 39 1 Remove the front panel of the case and lower the control panel. 2 Remove the fork C that holds the main circuit flow switch B (fig. 58). fig. 58 3 Start and stop the boiler in c/h operation (time switch and external controls must call for heat) and verify the position of the shaft D referring to fig.

  • Page 40: General Notes

    4 Assemble the part proceeding in reverse order. Assembling the part, ensure to place the concave side of the membrane towards the actuator plate H and the reference hole indicated in the seat I ( fig. 60 Removal of the switch 1.

  • Page 41: Flow Limiter

    13.3 Flow limiter If the flow rate of the d.h.w. circuit is too high, it is possible to limit it installing a flow limiter. The following sizes are available: Nominal flow rate (litres/min) Colour Blue To install the flow limiter operate as in the following sequence: 1.
  • Page 42 14.2 Checks Temperature-resistance relationship WARNING: isolate the boiler from the mains electricity supply before removing any covering or component. Disconnect the cable from the temperature probe. Measure the temperature of the pipe near the temperature probe and check the electrical resistance according to the graph in fig.

  • Page 43: By-Pass Valve

    1. remove the front panel of the case and lower the instrument panel 2. empty the main circuit of the boiler. 3. remove the electric connector of the temperature probe and unscrew it. 4. assemble the temperature probe carrying out the removal operations in reverse order. 15 By-pass valve 15.1 Function The by-pass valve is located between the c/h water flow and return (A in...

  • Page 44: Flue Fan, Venturi, Air Pressure Switch

    4 Remove the fork C and the pipe D. 5 Unscrew the connector E and remove the bypass valve F (fig. 70). fig. 70 6 Reassemble the by-pass valve as illustrated in fig. 70 and proceeding in reverse order. 16 Flue fan, venturi, air pressure switch 16.1 Function The boiler has a fan whose function is that of forcing the expulsion of the products of combustion.
  • Page 45 Check of the air pressure switch operation WARNING: isolate the boiler from the mains electricity supply before removing any covering or component. 1 Remove the front panel of the body and the lid of the sealed chamber 2 Disconnect the wires and check the electrical resistance between its connections Between COM and NO the contact must be open.

  • Page 46: Removal Of The Fan

    These switches are interchangeable. 3 Connect the black wire (COM) and the brown wire (NC). 4 Run the boiler (the fan must run) and check the the electric resistance between COM and NO Between COM and NO the contact must be closed (electrical resistance zero) Remember that in this condition the boiler runs only for the ignition safety time and than it goes on safety lock-out.

  • Page 47: Ignition And Detection Electrodes

    1. Remove the front panel of the body and the lid of the sealed chamber; 2. Disconnect the wires of the air pressure switch; 3. Remove the two pipes from the air pressure switch; 4. Unscrew the screw D (two for the pressure switch of fig.
  • Page 48 WARNING: isolate the boiler from the mains electricity supply before removing any covering or component. Remove the front panel of the body, the sealed chamber cover and the combustion chamber panel. Check for the correct distance between the metallic edges of the ignition electrodes and refer it to the fig.

  • Page 49: Safety Thermostat

    the metallic edge of the detection electrode is longer than the one of the ignition electrodes. 18 Safety thermostat 18.1 Function The safety thermostat (A in fig. 78) is a device that senses the temperature of the main circuit water which flows in the outlet pipe of the main heat exchanger.
  • Page 50 fig. 81 18.2 Checks WARNING: isolate the boiler from the mains electricity supply before removing any covering or component. Position of probe and integrity Remove the front panel of the case and the sealed chamber cover. Verify the soundness of the fitting between the main circuit pipe and the temperature probe C (fig.

  • Page 51: Short Spare Parts List

    thermostat and no overheat intervention should occur. It is not permissible to change the factory setting of the safety thermostat. The safety thermostat must be replaced if its operation temperature is too low and therefore constantly interrupts the correct functioning of the boiler and not allowing it to reach its maximum permissible operating temperatures.

This manual is also suitable for:

28s24sr47 970 0647 970 0741 970 03

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