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5.8
Burner starting
Operating control closes, the motor starts.
The pump 3)(Fig. 48) draws the fuel from the tank through the
piping 1) and pumps it under pressure for delivery.
The piston 4) rises and the fuel returns to the tank through the
piping 5) - 7).
The screw 6) closes the by-pass heading towards suction and
the de-energized solenoid valves 8) - 9) - 2) close the passage
to the nozzle.
Air damper and pressure regulator are positioned on MIN out-
put.
Ignition electrode strikes a spark.
Solenoid valves 8) - 9) - 2) open; the fuel passes through the
piping 10) and filter 11), and enters the nozzle.
A part of the fuel is then sprayed out through the nozzle, ignit-
ing when it comes into contact with the spark: flame at a low
output level; the rest of the fuel passes through piping 12 at
the pressure adjusted by the regulator 13, then, through piping
7), it goes back into the tank.
The spark goes out.
The starting cycle ends.
5.8.1
Steady state operation
At the end of the starting cycle, the servo-motor control then pass-
es to load control for boiler pressure or temperature.
If the temperature or pressure is low (and the load control is
consequently closed), the burner progressively increases out-
put up to MAX.
If subsequently the temperature or pressure increases until
the load control opens, the burner progressively decreases
output down to MIN.
The burner shuts off when demand for heat is less than the
heat supplied by the burner in the MIN output.
The servomotor returns to the 0° angle limited by contact with
cam 2. The air damper closes completely to reduce thermal
dispersion to a minimum.
Every time output is changed, the servomotor automatically modi-
fies oil delivery (pressure regulator) and air delivery (fan damper).
5.9
Flame signal measurement
Check the flame signal through the parameter 954, as indicated in
Fig. 49. The displayed value is expressed in percentage.
The value during the operation must be higher than 24%. If at the
burner start-up the value is higher or equal of 18%, the burner locks
out due to the extraneous light.
For further and specific information, please refer to the specific
instruction manual.
The display (Fig. 49) shows parameter 954: flashing on the left.
On the right, the flame's intensity is displayed as a percentage.
Example: 954: 0.0
Start-up, calibration and operation of the burner
35
D10157
5.8.2
Firing failure
If the burner does not fire, it goes into lock-out within 3 sec. of
the opening of the light oil valve.
If the flame should go out for accidental reasons during opera-
tion, the burner will lock out in 1 s.
S8171
GB
P
V
h min s
%
Fig. 48
Fig. 49
20095074
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