Table of Contents
Advertisement
6.8
Air / fuel adjustment
During the operations for calibrating the air/fuel ratio for oil
burners, the following adjustments need to be made:
A
Oil pump delivery pressure:
act on the screw 5)(Fig. 22) located on the pump.
B
Air cam:
act on the adjustment screws 2)(Fig. 36) after having
loosened the screws 3)(Fig. 36).
C
Gas cam:
act on the adjustment screws 2)(Fig. 36) after having
loosened the screws 3)(Fig. 36).
D
Oil cam:
modify the eccentricity by acting on the screw 4)(Fig. 37)
after having loosened the screws 7)(Fig. 37).
By tightening the screw 4)(Fig. 37) the eccentricity
increases, thereby increasing the difference between the
maximum and minimum return pressure returning from the
nozzle.
D8369
Key (Fig. 37)
1
Maximum oil pressure switch
2
Delivery pressure gauge
3
Return pressure gauge
4
Eccentric adjustment screw
5
Piston stop ring
6
Piston calibration nut and lock nut
7
Eccentric locking screws
8
Variable eccentric
Start-up, calibration and operation of the burner
Fig. 37
Burner calibration procedure
Install the nozzle suitable to achieve the maximum desired
output.
Verify that the eccentricity of the oil cam is such to make a
travel of about 8 mm on the shaft of oil modulator.
Normally, with a shaft stroke of 8 mm, the pressure variation
needed for the modulation of the minimum to maximum
output is obtained.
To verify this, manually rotate the cam after having released
the servomotor with the lever 7)(Fig. 38), so that the travel of
the shaft is not exaggerated or insufficient. Remember to
block the servomotor after the verification.
Switch on the burner, with the selector on the control panel
on manual 1)(Fig. 34).
At this point, after the pre-purging phase, the servomotor
stops at about 20°.
Adjust the outlet pressure of the pump as shown in point A
(oil pump outlet pressure) to obtain an outlet pressure to
the nozzle of 24 - 25 bar.
Adjust the minimum return pressure to approx. 6 bar.
To do so, the length of the shaft 5)(Fig. 37) must be varied
by means of nut 6)(Fig. 37).
Calibrate the air delivery by adjusting the variable profile
cam with the screws 2)(Fig. 36).
Having performed this first adjustment, increase the output
supplied via the automatic return selector on the control
panel. Pause after a 15° rotation of the servomotor and
perform another adjustment by means of the variable profile
cam of the air.
It is recommended to perform a calibration that will prevent
the formation of a smoky flame and arrive as soon as
possible to the maximum output (maximum stroke of the
servomotor 130°); on the eccentric (screw 4, Fig. 37),
calibrate the pressure on the return line to obtain the output
desired and requested by the nozzle, and then go back to
calibrate the intermediate points.
Then recheck the values of the combustion parameters at
the various modulation outputs and if necessary make the
necessary adjustments.
At this point shift the selector 3)(Fig. 34), to GAS and check
that the gas operation is operating correctly at the desired
output.
If this is not so, calibrate the gas cam as in point C (Gas
Cam) mentioned above.
With the optimal adjustment achieved, remember to lock the
adjustment screws of the cam profiles by means of screws
3)(Fig. 36).
When calibrating the cams, never go beyond the
travel limits of the servomotor 0° - 130° to avoid
any sticking. Carrying out a manual travel 0 -130°
of the cams, check that there are no mechanical
ATTENTION
stops before the micro-switches 1-2 of the
servomotor are activated.
31
GB
20148124
Advertisement
Table of Contents
