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4.12.3 Hydraulic connections
Make sure that the flexible hoses to the pump sup-
ply and return line are installed correctly.
CAUTION
Follow the instructions below:
tighten the flexible hoses with the supplied gas-
kets.
WARNING
Take care that the hoses are not stretched or
twisted during installation.
Place the pipes so that they are not crushed or
are in contact with hot parts of the boiler and so
it is possible to open the burner.
Finally, connect the other end of the flexible
hoses to the suction and return pipes.
4.12.4 Hydraulic circuit layout
Key (Fig. 24)
1
Pump suction
2
Pump pressure regulator
3
Filter
4
Oil pressure gauge
5
Min. Oil pressure switch
6
Safety valve
7
Discharge valve
8
Control valve
9
Oil modulator
10 Air solenoid valve
11 Air pressure switch
12 Air pressure gauge
13 Nozzle
14 Max oil pressure switch
P
Pressure gauge connection
V
Vacuometer connection
OPERATION
Pre-purging phase: valves 6) closed.
Ignition and operation phase: valves 6) opened.
Stop: all valves closed.
4.12.5 Pressure variator
The pressure variator (Fig. 25), incorporated in the oil circuit valve
group, makes it possible to vary the pressure on the nozzle line de-
pending on the output required. The pressure on the nozzle line is
adjusted by varying a section by means of the rotation of the ser-
vomotor, which also controls the gas butterfly valve at the same
time.
Regulator to 0° (minimum opening) = minimum pressure on
nozzle line.
Regulator to 90° (maximum opening) = maximum pressure on
nozzle line.
The servomotor is controlled by the electronic cam; thanks to this
device, it is possible to set different curves for oil and gas on the
same servomotor (also for the air damper servomotor.
When adjusting the gas, it is recommended to adjust the servo-
motor to about 90° to reduce leaks from the gas butterfly valve.
When adjusting the oil, the adjustment is done based on the
nozzle fitted and on the required degree of modulation; in a sit-
uation of minimum firing rate, a rotation of 20° can be enough.
Installation
1/2" NPT
5
6
4
3
V
P
1
2
OUTLET
Key (Fig. 25)
1
Outlet pressure gauge
2
Position indicator (0 ÷ 90) of the pressure variator
3
Max oil pressure switch
27
GB
Air Valve
10
12
8
11
14
6
4
4
9
7
8
3
2
20159158
13
8
20159149
Fig. 24
INLET
1
Fig. 25
20142253
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