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4.12.2 Adjustment and calibration of the oil circuit
and of the air output
The oil supply system requires that suction of the fuel occurs from
a degassing tank, using a self-priming pump, and that the fuel is
sent to the burner at the correct pressure.
This pressure is calibrated using the regulator built into the pump
(Fig. 21) after having unscrewed the protection plug (to regulate
the pressure, see the attached diagrams of the nozzles.
The modulation of the oil flow rate is carried out using the
pressure regulator 1)(Fig. 22).
It works by varying the pressure on the return line from the
nozzle, this pressure can be measured using the pressure gauge
2)(Fig. 22) after slightly unscrewing the valve 3)(Fig. 22) (it is
advisable, when the burner is operating normally, to keep the
valves 3)(Fig. 22) of the pressure gauges closed to prevent any
water hammers damaging them).
To set the delivery range within which the nozzle must work,
nozzle return line fuel maximum and minimum pressure must be
adequately adjusted.
For correct functioning at the minimum, the return pressure, read
on the pressure gauge 2), must be approx 4 - 5 bar.
Regulator to 0° (maximum opening) = minimum pressure on
the nozzle return line;
Regulator to 90° (minimum opening) = maximum pressure
on the nozzle return line.
The servomotor is controlled by the electronic cam present in the
boiler main panel; 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 9)(Fig. 8, on page 12).
When adjusting the gas, it is recommended the servomotor
be adjusted 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 situation of minimum firing rate, a rotation of 20° can be
enough.
20169350
Installation
VIEW FROM MOTOR SIDE
Rotation direction to the right
1
Key (Fig. 21)
1 Pressure gauge connection
2 Delivery line
3 Return line
4 Pressure regulator (unscrew the plug)
5 Suction line
Key (Fig. 22)
1 Indicator for the position of modulator
2 Return pressure gauge
3 Shut-off valve for pressure gauge
20
GB
2
3
D1498
2
3
20121578
4
5
Fig. 21
1
Fig. 22
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