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8.5
Burner operation
8.5.1
Burner start-up
0 s:
TL remote control closing, motor starting.
The pump 3) sucks the fuel from the tank through the
piping 1) and the filter 2) and pumps it under pressure to
delivery. The piston 4) rises and the fuel returns to the
tank through the piping 5) - 7). The screw 6) closes the
by-pass towards the suction line and the solenoid valves
8)-15)-16), de-energised, closing the path towards the
nozzle.
5 s:
Start-up servomotor: 90° rotation to the right, until the
contact intervenes on the cam I. The air damper is
positioned to MAX output.
24 s:
Pre-purging stage with MAX output air delivery.
54 s:
The servomotor rotates to the left until the contact on
cam III) activates.
70 s:
The air damper and the pressure variator set to the MIN
output position.
72 s:
Ignition electrode strikes a spark.
76 s:
Solenoid valves 8) - 15) - 16) open; the fuel goes
through the duct 9), passing through the filter 10) and
enters the nozzle. A part of the fuel is sprayed out of the
nozzle and when it reaches the spark ignites: low output
flame, point A; the rest of the fuel goes through the duct
11 at the pressure preset by the variator 12, then it goes
back to the tank through the duct 7).
78 s:
The spark goes out.
96 s:
The start-up cycle ends.
8.5.2
Steady state operation
Burner without output regulator RWF
Once the start-up cycle is completed, the servomotor command
moves on to the TR remote control that controls the pressure or
the temperature in the boiler, point B.
–
If the temperature or pressure is low (so the TR remote
control is closed), the burner progressively increases the
output up to the MAX value (section B-C).
–
If subsequently the temperature or pressure increases until
TR opens, the burner progressively decreases its output to
the MIN value (section D-E). And so on.
–
The burner locks out when the heat request is less than the
heat supplied by the burner at MIN output, (section F-G).
–
The TL remote control opens, the servomotor returns to
angle 0° limited by the contact of cam II. The air damper
closes completely to reduce heat losses to a minimum.
With each change of output, the servomotor automatically
modifies the light oil output (pressure variator) and the air flow
rate (fan damper).
Burner with output regulator RWF
See the manual supplied with the regulator.
Start-up, calibration and operation of the burner
M
72
VM
VU
VS
76
24 54
MAX
70
M
MIN
0
5
2°
A B
1°
0
76 96
78
0 sec
8.5.3
Ignition failure
If the burner does not ignite, it locks out within 5 seconds after the
light oil valve opens, 78 s after the TL closes and the post-purging
phase starts lasting 12s.
8.5.4
Burner flame goes out during operation
If the flame should accidentally go out during operation, the
burner will lock out within 1s.
27
GB
78
C
D
E
20171022
F
G
Fig. 34
D873
Fig. 35
20167399
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