12
NOTE
The servomotor follows the adjustment of cam
III only when the angle of the cam is reduced. If
it is necessary to increase the angle of the cam,
you must first increase the angle of the servo-
motor by means of the “output increase” key,
then increase the angle of cam III, and finally
bring the servomotor to the position of MIN out-
put, with the “output reduction” key.
If it is necessary to adjust cam III, remove the
cover 1) (inserted with a trigger catch, as indi-
cated in fig. (B), extract the special key 2) from
inside, and insert it in the notch of cam III.
Adjustment of air delivery
Progressively adjust the starting profile of cam
4)(A) by turning the screws working through the
access hole 6)(A). It is preferable not to turn the
first screw since this is used to set the air
damper to its fully closed position.
2 - MAX. OUTPUT
Max. output of the burner must be set within the
firing rate range shown on page 5.
In the above description, we left the burner
switched on, working at MIN output. Now press
the button 2)(A)p.11 “output increase”, and keep
it pressed until the servomotor has opened the
air damper and the gas butterfly valve at 90°.
Adjusting gas delivery
Measure the gas delivery at the meter.
As a general rule, it can be seen from the table
on page 6, just read the gas pressure on the
pressure gauge, see fig.(C)p.10, and follow the
indications given on page 6.
- If delivery needs to be reduced, diminish out-
let gas pressure and, if it is already very low,
slightly close adjustment valve VR.
- If delivery needs to be increased, increase
outlet gas pressure.
Adjustment of air delivery
Progressively adjust the end profile of cam 4)(A)
by turning the cam adjustment screws as they
appear through the access opening 6)(A).
- Turn the screws clockwise to increase air
delivery.
- Turn the screws anti-clockwise to reduce air
delivery.
3 - INTERMEDIATE OUTPUTS
Adjusting gas delivery
No adjustment of gas delivery is required.
Adjustment of air delivery
Press the key 2)(A)p.11 “output increase” a little
so that a new screw 5)(A) appears in the open-
ing 6)(A). Adjust it until optimal combustion is
obtained. Proceed in the same way with the
other screws.
Take care that the cam profile variation is pro-
gressive.
Switch the burner off with the switch 1)(A)p.11.
Release the variable profile cam by putting the
servomotor slot 2)(A) in a vertical position and
check more than once, rotating the cam forward
and backward by hand, that the movement is
soft and smooth, without sticking.
As far as is possible, try not to move those
screws at the ends of the cam that were previ-
ously adjusted for the opening of the air damper
to MAX and MIN output.
NOTE
Once you have finished adjusting outputs MAX -
MIN - INTERMEDIATE, 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 delivery.
(A)
(B)
D518
D793
1 Servomotor
2
Constraint /
Release of cam 4
3 Cam cover
4 Variable profile cam
5 Screws for adjusting the variable profile
6 Slit to access the screws 5
7 Index of graduated sector 8
8 Gas butterfly valve graduated sector
