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5.7
Burner starting
Operating control closes, the motor starts.
The pump 3) (Fig. 45) 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.
5.7.1
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).
5.8
Final checks (with the burner working)
Open the control limit operation
Open the high limit operation
Rotate the maximum gas pressure switch knob to the mini-
mum end-of-scale position
Rotate the air pressure switch knob to the maximum end of
scale position
Rotate the maximum oil pressure switch at the minimum of
the scale
Switch off the burner and disconnect the voltage
Disconnect the minimum gas pressure switch
Rotate the minimum low oil pressure switch at the maximum
of the scale
Cover the UV flame sensor
Make sure that the mechanical locking systems on
the different adjustment devices are fully tightened.
WARNING
20026897
Start-up, calibration and operation of the burner
32
D10157
5.7.2
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.
The burner must stop
The burner must stop in lockout
The burner must not start
The burner must stop in lockout due to firing failure
GB
Fig. 45
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