Servicing Manual
10
2.3 FUEL CIRCUIT
Description
The fuel circuit is basically composed of :
tank
suction and return hoses
fuel filter,
fuel pump,
fuel solenoid valve,
high pressure microhose
combustion head
nozzle
The gear pump, driven by the motor, sucks fuel from the tank and increases its pressure to the rated value.
At the pump outlet a fuel cut-out solenoid valve SV is fitted. The pump is controlled by the flame control
unit. During normal operation the valve is open and the pressurized fuel flows to the nozzle, where it is
atomized, mixed with primary combustion air and ignited by the electrode spark. The flow of primary air
to the burner is adjusted by an air lock on the combustion head.
Under abnormal operating conditions (see also flow-chart) the flame control unit closes the solenoid
valve SV, fuel does not come to the nozzle but goes back to the tank through the return hose. An
adjustment screw is fitted on the front of the pump ; it allows to adjust the pressure and consequently the
fuel flow.
ILL. 2: particolare gruppo filtro gasolio
ILL. 3: particolare pompa gasolio
2.4 BURNER HEAD/COMBUSTION CHAMBER
