Ferroli Falcon II, Installation, Servicing And User Instructions Manual

FALCON  II

33

8.04 Temperature sensors (thermistors)

Identical, but individual, negative temperature co-efficient (NTC) thermistors are fitted in the C.H. and D.H.W. outlets 
from the heat exchanger. As the water temperature increases the resistance in the thermistor decreases. This causes 
the PCB to reduce the voltage to the modureg, in turn reducing the burner pressure. The wiring for each thermistor 
is colour coded red for C.H. and blue for D.H.W. The sensors are fitted in wet pockets.

8.05 Limit thermostats

Two surface mounted auto reset bi-metal thermostats are located on the heat exchanger secured by spring 
clips. Heat sink compound is used.

8.06 Ignition PCB

Located to the right hand side of the electrical control compartment accessed by lowering the facia then 
removing the rear cover.

8.07 Main printed circuit board

Secured by three screws, the PCB is situated inside the control compartment. The transformer for low voltage 
AC is attached to the PCB as is the DC rectifier. Potentiometers control C.H. output and maximum D.H.W. 
temperature, both are adjustable by the controls on the facia and because the boiler features automatic 
range rating no adjustments need to be made. Electro mechanical relays control pump operation and 
put switched live to the ignition PCB (demand relay), they have transparent plastic covers so that their 
contacts can be seen moving.

8.08 Air pressure switch

Operating at 230 V AC and situated next to the fan. Different coloured tubes connect the switch to the fan. It is a 
make on pressure switch and only uses two terminals, the middle terminal is not used.

8.09 Short spares list

  KEY NO.                    DESCRIPTION                                                             PART NO.            G.C. NO.
 (from fi g 2 )

          14                        Safety Valve                                                                     800130                  386-816
          16                        Fan                                                                                    800480                  E23-851
          34                        Central Heating Flow Temperature Sensor                     800320                  E23-839
          39                        Cold water flow limiter
          42                        Domestic Hot Water Flow Temperature                        
                                      Sensor                                                                              800320                  E23-839
          43                        Air Pressure Switch                                                          800150                  E23-840
          44                        Honeywell Gas Valve                                                       800266                  E23-768
          49                        Overheat Safety Thermostat 100°C                                801270                  386-815
          50                        High Limit Thermostat 88°C                                            800160                  386-577
          81                        Ignition Electrode °/N fixing Bracket                              806460
          82                        Flame Sensing Electrode                                                 801438                  E23-855
          136                      Flow Meter                                                                       803430                  E03-340
                                      Main PCB MF03                                                                                           
          27                        Heat Exchanger                                                               802180                  E23-919