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6.8
Burner operation
6.8.1
Burner start-up
(gas trains in compliance with EN 676)
• 0s : Control remote control TL closes.
•
: Servomotor start-up: rotate to the right by 130°, i.e. until
6s
the contact intervenes on the cam I (Fig. 27 on
page 29).
The air damper is positioned to MAX output.
• 51s : Pre-purging stage with MAX output air delivery.
Duration 31 seconds.
•
: The servomotor rotates to the left until reaching the
82s
angle set on cam III (Fig. 27 on page 29) at 20°.
•
: The air damper and gas butterfly valve assume the MIN
120s
output position - with cam III (Fig. 27 on page 29) at
20°).
• 121s : Ignition electrode strikes a spark.
•
: The safety valve VS opens, along with the adjustment
valve VR, (quick opening). The flame is ignited at a low
127s
output level, point A.
The output is then progressively increased, with the
valve opening slowly up to MIN output, point B.
• 130s : The spark goes out.
• 150s : The start-up cycle ends
6.8.2
Steady state operation
STEADY STATE OPERATION
Burner without output regulator RWF50
At the end of the start-up cycle, the servomotor control switches
to TR remote control that controls the pressure or temperature in
the boiler, point C. (The electric control box RFGO carries on
checking the presence of the flame and the correct position of the
air and gas maximum pressure switches).
•
If the temperature or pressure is low (so the TR remote con-
trol 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 remote control opens, and the servomotor returns to angle
0° limited by the contact of cam I (Fig. 30 on page 30). The
air damper closes completely to reduce heat losses to a min-
imum.
Upon every output change, the servomotor will automatically
change the gas flow rate (butterfly valve), the airflow (fan damp-
er) and the air pressure (2 shutters in the combustion head).
Burner with output regulator RWF50
See the manual supplied with the adjuster.
Start-up, calibration and operation of the burner
Burner flame goes out during operation
If the flame should accidentally go out during operation, the burn-
er will lock out within 1s.
51
MAX
MIN
0
6
MAX
MIN
0
0 sec
20194414
6.8.3
Ignition failure
If the burner does not ignite, it locks out within 3 s after the gas
valve opens, 130 seconds from TL closure and the post-purging
phase starts and lasts in 18 seconds.
M
127
MAX
MIN
0
6
0 sec
20194415
35
GB
STANDARD IGNITION
121
130
127
82
120
D
E
B
C
F
A
127
150
IGNITION FAILURE
130
G
H
Fig. 37
Fig. 38
20148758
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