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6.11
Operation sequence of the burner
6.11.1 Burner start-up
• 0s
TL thermostat/pressure switch closure.
Fan motor start-up.
• 6s
Servomotor start-up: rotate to the right by 130°, i.e. until
the contact intervenes on the cam 1).
If it's operating with oil or cam 4) if it's operating with
gas.
• 48s
The air damper is positioned to MAX output.
Pre-purging stage with MAX output air delivery.
• 80s
The servomotor rotates towards the left until the angle
set on the cam 3).
If it's operating with oil or cam 5) if it's operating with
gas.
• 109s The air damper and the gas butterfly valve adopt the
MIN output position.
• 113s Ignition electrode strikes a spark.
• 116s The pilot valves VP1 and VP2 open.
The flame is ignited at a low output level, point A
(Fig. 42).
• 119s The spark goes out.
• 130s The safety valve VS opens, along with the adjustment
valve VR (quick opening).
The output is then progressively increased, with the
valve opening slowly up to MIN output, point B
(Fig. 42).
• 143s The start-up cycle ends.
STANDARD IGNITION
M
VP1
VP2
VS
VR
M
20148124
Start-up, calibration and operation of the burner
20160525
Fig. 42
6.11.2 Steady state operation
Burner without output regulator RWF
Once the start-up cycle is completed, the servomotor command
moves on to the TR thermostat/pressure switch that controls the
pressure or the temperature in the boiler, point C (Fig. 42).
(The electrical control box continues to check the presence of the
flame and the correct position of the air and gas maximum
pressure switches).
–
If the temperature or the pressure is low so the thermostat/
pressure switch TR is closed, the burner progressively
increases the output up to the MAX value (section C-D).
–
Then if the temperature or pressure increases until the TR
opens, the burner progressively decreases its output to the
MIN value (section E-F). And so on.
–
The burner locks out when the heat request is less than the
heat supplied by the burner at MIN output, (section G-H).
The TL thermostat/pressure switch opens, and the
servomotor returns to angle 0° limited by the contact of cam
2).
The air damper closes completely to reduce heat losses to a
minimum.
For every change of output, the servomotor will automatically
change the gas flow rate (butterfly valve), the airflow (fan
damper) and the air pressure (2 shutters in the combustion
head).
Burner with output regulator RWF
See the manual supplied with the regulator.
6.11.3 Burner flame goes out during operation
If the flame should accidentally go out during operation, the
burner will lock out within 1s.
6.11.4 Ignition failure
If the burner does not ignite (Fig. 43), it locks out within 3 s after
the gas valve opens, 119 s after the TL closes and the post-
purging phase starts lasting 17s.
M
VP1
VP2
VS
VR
M
34
GB
20160526
Fig. 43
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