Table of Contents
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Summary of Contents for Savio GAIA 424 S
- Page 1 Wall hung, fan flue, room sealed gas boiler GAIA Service manual Leave this manual adjacent to the gas meter Models: 424 S 428 S 424 RS BIASI S.p.A. 37135 Verona (Italy) Via Leopoldo Biasi, 1 Stabilimento: 33170 Pordenone (Italy) Via Pravolton, 1/B...
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Page 3: Table Of Contents
Table of contents 11 Full sequence ignition device ... . 11.1 Function ......11.2 Checks . -
Page 5: Overall Information
Overall information Overall View Automatic air release valve Main heat Expansion vessel exchanger Air pressure Safety switch thermostat probe Ignition electrodes Combustion chamber Burner D.h.w. Detection heat exchanger electrode Gas valve Pump D.h.w. Diverter valve outlet D.h.w. inlet D.h.w. temp probe flow D.h.w. -
Page 6: General Access And Emptying Hydr. Circuits
General access and emptying hydraulic circuits Nomenclature fig. 4 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 of the frame. To remove the lower protection plate completely un- screw the screws B and remove the plate (fig. -
Page 7: Control Panel
General access and emptying hydraulic circuits 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 gain access to the parts located inside the control panel remove the four screws D (fig. -
Page 8: Diagrams
Diagrams Wiring diagram Air pressure Water pressure Water pressure switch switch switch High limit Low limit (red plug) (brown plug) Ignition Flame detection Safety Reset push Shutdown electrodes electrode thermostat button lamp Display circuit type 10.81 Ignition and flame control device Control circuit type 10.80 Pump... -
Page 9: Functional Flow Diagrams
Diagrams Functional flow diagrams General layout L --- LINE N --- NEUTRAL ACTIVE CIRCUIT function switch position off INACTIVE CIRCUIT F2 (1,6 A T) TRANSFORMER J4--- 1 21V= TO THE CONTROL CIRCUIT’ S LOW K1 (RELAY) VOLTAGE SECTION 12V= J4--- 4 IGNITION DEVICE K2 (RELAY) - Page 10 Diagrams Function switch position L --- LINE N --- NEUTRAL ACTIVE CIRCUIT Heat request on d.h.w. INACTIVE CIRCUIT F2 (1,6 A T) TRANSFORMER J4--- 1 21V= TO THE CENTRAL CIRCUIT’ S K1 (RELAY) LOW VOLTAGE SECTION 12V= J4--- 4 IGNITION DEVICE (or gas valve)* K2 (RELAY)
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Page 11: Control Circuit Voltages
Diagrams Control circuit voltages 230 V~ network D.h.w. Room thermostat flow switch Ignition device Circulator D.h.w. flow switch Main circuit temperature probe D.h.w. temperature probe a: never zero (short circuit) never 12V= (open circuit) Modulating operator Electronic control circuit Ignition device Overheat thermostat Shut--- down lamp... -
Page 13: Fault Finding
Fault finding... - Page 14 Fault finding...
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Page 15: Main Heat Exchanger
Main heat exchanger Characteristics The main heat exchanger (A in fig. 12) has the function of transferring heat of the gas produced by combus- tion to the water circulating in it. fig. 14a For model 428 S... Remove the front part of the flue gas hood by un- screwing the four screws C (fig. -
Page 16: H.w. Heat Exchanger
D.h.w. heat exchanger Remove the front panel of the case and lower the instrument panel Function Completely unscrew the two Allen key screws B (in fig. 17 the right one is shown) which hold the The d.h.w heat exchanger (A in fig. 15) allows the in- exchanger to the brass deviator groups;... -
Page 17: Pump
Pump Check the absence of starting defects. With the boiler off remove the front panel and lower the Function control panel; The pump (A in fig. 19) has the function of making the for Myson pump: unscrew the plug of the pump by hand water in the main circuit circulate through the main heat (the plug cannot be removed). -
Page 18: Diverter Valve And D.h.w. Pressure Switch
Diverter valve and d.h.w. pressure switch Function The diverter valve (A in fig. 22) has the function of mod- ifying 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. - Page 19 Diverter valve and d.h.w. pressure switch 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 refer- ence shaft J in the seat of the valve (fig. 28). fig.
- Page 20 Diverter valve and d.h.w. pressure switch Unscrew the screw R that holds the d.h.w. heat exchanger, the bolt S that holds the valve to the frame (fig. 33) and remove the valve. fig. 30 Remove the forks M and move away the pipes N (fig.
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Page 21: Electronic Control Circuit
Electronic control circuit Several of these devices are directly accessible by the user (function switch, temperature adjustment poten- tiometers etc.) others are accessible by removing the Function cover. Inlet Information d.h.w. temperature probe main circuit temperature probe d.h.w. pressure switch c/h flow switch function switch d.h.w. -
Page 22: Function Selectors
Electronic control circuit Function selectors Primary NTC The function selectors ” 6” (fig. 36 and fig. 39) are microswitches with which it is possible to select the vari- ous modes of functioning of the boiler. In fig. 39 the selectors are illustrated in the configur- ation in which the p.c.b. -
Page 23: Ignition Gas Pressure Regulator
Electronic control circuit Ignition gas pressure regulator By using the device ” 8”(fig. 36) marked “ ACC.”on the circuit board, it is possible to adjust the gas pressure at the injectors in the ignition phase. (1,6 A) This pressure is maintained at the injectors until ignition occurs (ionization signal). - Page 24 Electronic control circuit assemble the control circuit following the disas- sembly procedures in the reverse order. Attention: in order to facilitate the mounting of the cover: position the knobs of the panel as illustrate in fig. 47; fig. 48 position the spindles as in fig. 49 and mount the panel cover.
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Page 25: Thermal Control In The " "Mode
Electronic control circuit Thermal control in the ” ”mode Switch in the function mode Green LED on See functioning with the function Taking water from the domestic hot switch in the mode (sec. 9.10) water circuit? Is primary circuit temperature higher than that selected? Request for heat from room thermostat? -
Page 26: Display Circuit
Display circuit This light indicates the heat request signal from the electronic control circuit and it comes on when the water temperature (d.h.w. or c.h. circuit) is lower than 10.1 Function the requested on the control panel. The boiler is equipped with a pcb that displays some in- During d.h.w. -
Page 27: Full Sequence Ignition Device
Full sequence ignition device While the burner is on, turn the gas supply off. The de- vice should carry out a complete ignition cycle and then shutdown. 11.1 Function When turning the boiler on and off with the function The ignition and flame control device, type S4565DD, switch, the device should not reset itself and the burner used on electronic ignition boilers with forced flue gas should not turn on. -
Page 28: Ignition Sequence
Full sequence ignition device 11.4 Ignition sequence Supply from the electronic control circuit Shutdown memorised? Resets shutdown Fan pressure switch in standby? Starts fan Stops fan Memorizes shutdown Shutdown indicator light turns on Fan pressure switch working? Wait time starts Wait time starts Presence of flame? -
Page 29: Gas Valve
Gas valve 12.1 Function 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 modulat- ing operator the pressure can be varied and therefore the gas flow rate to the burner (modulation). -
Page 30: Removal
Gas valve trical resistance of the coil. Remove the front panel of the case and lower the Its electrical resistance value must be approx. control panel. 125 O. Remove the full sequence ignition device (see the Check the modulating operator coil section 11.3 of this manual). -
Page 31: Main Circuit Flow Switch
Main circuit flow switch 13.1 Function The main circuit flow switch (A in fig. 62) is a device that controls the speed of water that crosses the main heat exchanger. fig. 63 Mechanical function Remove the front panel of the case and lower the control panel as described in the section 2.2 of this manual. -
Page 32: Removal
Main circuit flow switch 13.3 Removal Assemble the part proceeding in reverse order. Assembling the part, ensure to place the concave Warning: isolate the boiler from the mains side of the membrane towards the actuator plate H electricity supply before removing any and the reference hole indicated in the seat I covering or component. -
Page 33: H.w. Filter And Flow Limiter
D.h.w. filter and flow limiter 14.1 General notes The input port of the d.h.w. circuit is provided wit a net filter and its function is to stop the passage of any impu- rities through the circuit. The d.h.w. filter is located in the c.h. return group (indi- cated in fig. -
Page 34: Temperature Probes
Temperature probes probe) A, (fig. 71 and fig. 72) one on its input, before the pump (d.h.w. temperature probe) B (fig. 71 and fig. 73). 15.1 Function The temperature probe has the function of converting the temperature of the water of the hydraulic circuit where it is installed into an electric signal (resistance). -
Page 35: Removal
Temperature probes 15.3 Removal Warning: isolate the boiler from the mains electricity supply before removing any covering or component. To remove the main circuit or the d.h.w. tempera- ture probes follow the same sequence. Refer to fig. 72 for the main circuit temperature probe, to fig. -
Page 36: By -- Pass Valve
By---pass valve remove the hydraulic actuator B (fig. 75) as ex- plained in the section Diverter valve and d.h.w. 16.1 pressure switch of this manual; Function remove the fork C and the pipe D. The by---pass valve is located between the c/h water flow and return (A in fig. -
Page 37: Checks
Water pressure switch and disconnect the connectors to the pressure switches and measure the electrical resistance pump relay between the connections (fig. 78). 17.1 Function When the circuit is empty, the contact between The boiler is equipped with two water pressure the connection COM and the connection NC switches which are connected to the main (c.h.) water must be closed;... -
Page 38: Flue Fan, Venturi, Air Pressure Switch
Flue fan, venturi, air pressure Check of the air pressure switch operation switch Warning: isolate the boiler from the mains electricity supply before removing any covering or component. 18.1 Function Remove the front panel of the body and the lid of The boiler has a fan whose function is that of forcing the the sealed chamber expulsion of the products of combustion. -
Page 39: Removal Of The Fan
Flue fan, venturi, air pressure switch 18.4 Removal of the air pressure switch Note that there are two different air pressure switches with different operating values for the 424 S, 424 RS and 428 S boilers. Refer to the short spare parts list for the correct selection of the switch. -
Page 40: Ignition And Detection Electrodes
Ignition and detection electrodes Check the integrity of the detection electrode and en- sure that its metallic edge is correctly placed over the ramp of the burner. 19.1 Function Three electrodes are fitted on the burner. Two of them Check the connection wires are the ignition electrodes and are fitted near the front part of the burner. -
Page 41: Safety Thermostat
Safety thermostat and the electric switch D which is fitted in the con- trol panel (fig. 89) 20.1 Function The safety thermostat (A in fig. 86) is a device that senses the temperature of the main circuit water which flows in the outlet pipe of the main heat exchanger. If the temperature control system of the boiler fails and the temperature of the main circuit reaches a danger- ous temperature, the safety thermostat opens the elec-... -
Page 42: Removal
Safety thermostat reach its maximum operating temperature (monitor the disconnect the switch; temperature display on the control panel). The boiler unscrew the nut that holds the switch to the should operate and maintain a temperature below that bracket E and remove the thermostat; of the safety thermostat and no overheat intervention should occur. - Page 43 Safety thermostat...
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Page 44: Short Spare Parts List
Short spare parts list Key G.C. part no. Description Q.ty Manufac- Manufacturer’ s reference turer part no. E01 167 13 ramps burner (mod. 424) BG1003 101 Polidoro E01 224 15 ramps burner (mod. 428) BG1013 105 E01 155 Injectors for natural BG1013 502 E01 156 Injectors for LPG... - Page 45 Short spare parts list...
- Page 48 *1796206821* 17962.0682.1 9811 (12A3)
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