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5.10
Combustion head adjustment
The combustion head moves simultaneously with cam
8)(Fig. 19), the variable profile cams and the gas butterfly. Head
position can be seen on cylinder 2)(Fig. 15).
The head control lever systems are factory-calibrated for maxi-
mum travel.
If a different modulation range is required, these levers must be
recalibrated so that head travel takes place as illustrated in the
following graph (Fig. 16).
For ignition difficulty proceed as follows:
Adjust the fuel pressure on the return line
between 5 ÷ 8 bar and regulate the air for a
correct combustion.
ATTENTION
If difficulties persist, set the combustion head
to the minimum on notch 2 ÷ 3, keeping the
adjustment of the maximum delivery as in the
diagram.
Example:
With burner 4500, for modulation from 1.400.000 to 3.400.000
kcal/h you see from the graph: notch l for 1.400.000 kcal/h. notch
6,5 for 3.400.000 kcal/h, with a travel of a 5.5 notches.
NOTE:
To avoid causing knocking, never exceed maximum and
minimum aperture positions corresponding, respectively,
on cylinder 2)(Fig. 15), to notch 9 with the servomotor at 130°
and notch 0 with the servomotor at 0°.
To modify combustion head travel, proceed as follows:
Con-rod 1), which controls drive rod of the combustion head,
is fitted with a slot; when tie-rod 9) is moved towards the
outside of the slot, head travel decreases by about 20 mm
(approx. 4 notches).
20176605
Installation
If a larger reduction is required, proceed as follows:
With the servo-motor at 0°, slacken screws 5) and push ring
6) under the variable - profile cam in the direction of the
arrow. This reduces eccentricity and thus decreases travel.
Having established the required travel, fully secure screws
5).
In the previous example (travel of 5.5 notches), travel start-end
must coincide with the required values of 1 and 6.5.
To obtain this, turn hex. sleeve 3) one way or the other after hav-
ing slackened nuts 4).
With the servo-motor positioned at 0°, notch 1) must coincide with
reference surface 10); when the servo-motor is positioned at
130°, it must coincide with notch 6.5.
Having completed the adjustment, fully secure nuts 4) with ball-
joint 8) positioned as shown in the Fig. 15.
Head calibrations are performed with the burner closed and not
operating and with the servo-motor released.
Having completed the adjustment, manually check cam 7) travel
to ensure there is no knocking between 0° and 130°.
Output
20
GB
S7971
Fig. 15
S7970
Fig. 16
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