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7.3.4
MIN power
Min. output must be selected within the firing rate range seen on
page 11.
Press button 2)(Fig. 30) "output reduction" and keep it pressed
until the servomotor has reached 20° (factory setting).
D791
Nozzle flow rate adjustment
The nozzle flow rate is given in diagram (Fig. 27) corresponding
to the pressure on the nozzle return read on the pressure gauge
1)(Fig. 28).
The output and the pressure of the nozzle are at minimum when
the servomotor is positioned on 20°.
To set return pressure, see page 23.
Adjusting air delivery
Progressively adjust the starting profile of cam 2)(Fig. 29) by turn-
ing the screws 3).
It is preferable not to turn the first screw since this is used to set
the air gate valve to its fullyclosed position.
7.3.5
Intermediate power
Air/oil flow rate adjustment
Press the switch 2)(Fig. 30) "output increase" a little so that the
servomotor turns by about 15°. Adjust the screws until optimal
combustion is obtained.
Proceed in the same way with the other screws.
Take care that the cam profile variation is progres-
sive.
WARNING
Switch the burner off with switch 1)(Fig. 30), at the OFF position,
disengage the cam 2)(Fig. 29) from the servomotor, by pressing
the button 3)(Fig. 31) and moving it to the right, and check more
7.4
Oil pressure switch
The oil pressure switch 5)(Fig. 4 at page 12) is factory set to
3 bar. If the gas oil pressure reaches this value in the return pip-
ing, the pressure switch stops the burner.
Burner starts again automatically if the pressure goes down un-
der 3 bar after burner shut down.
If a loop circuit with Px pressure feeds the burner, the pressure
switch should be adjusted to Px + 3 bar.
20033333
Start-up, calibration and operation of the burner
1
2
than once that the movement is soft and smooth, and does not
grip, by rotating the cam 2) forward and backward by hand.
Engage cam 2) to the servomotor again by moving button
2)(Fig. 31) to the left.
As far is possible, try not to move those screws at the ends of the
cam that were previously adjusted for the opening of the airgate
to MAX and MIN output.
Once you have finished adjusting outputs MAX - MIN - INTER-
MEDIATE, check ignition once again: noise emission at this
stage must be identical to the following stage of operation.
If you notice any sign of pulsations, reduce the ignition stage de-
livery.
Fig. 30
Finally fix the adjustment by turning screws 4)(Fig. 29).
NOTE
The servomor follows the adjustment of cam III only when the
cam angle is reduced. If it is necessary to increase the cam an-
gle, first increase the servomotor angle with the key "output in-
crease", then increase the III cam angle, and finally bring the
servomotor back to the MIN output position with the key "output
decrease".
In order to adjust cam III, especially for fine movements, key
10)(Fig. 31), held by a magnet under the servomotor, can be
used.
24
GB
D889
Fig. 31
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