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6.8
Burner operation
6.8.1
Burner start-up
•
0s:Control remote control TL closes.
Fan motor start-up.
•
6s:Servomotor start-up: turn to the right by 130°, i.e. until the
contact intervenes on cam I (Fig. 30 on page 30).
The air damper is positioned to MAX output.
•
48s:Pre-purging stage with MAX output air delivery.
Duration 32 s.
•
80s:The servomotor turns to the left to reach the angle set on
cam III (Fig. 30 on page 30) for the MIN output.
•
112s:The air damper and gas butterfly valve assume the MIN
output position (with cam III)(Fig. 30 on page 30) at
15°.
•
113s:Ignition electrode strikes a spark.
•
119s:The safety valve VS opens, along with the adjustment
valve VR, (quick opening). The flame ignites with a
small output - point A.
The output gradually increases, and the VR valve
slowly opens, until MIN output is reached - point B.
•
122s:The spark goes out.
•
135s:The start-up cycle ends.
6.8.2
Steady state operation
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 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
control is closed), the burner progressively increases the
output up to the MAX value (section C-D).
•
If the temperature or pressure then increases until the TR
opens, the burner progressively decreases its output to the
MIN value (section E-F). And so on.
20152093
Start-up, calibration and operation of the burner
20156543
Fig. 38
•
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 II (E) page 12. The air
damper closes completely to reduce heat losses to a
minimum.
With each change of output, the servomotor automatically
modifies the gas output (butterfly valve) and the air flow rate (fan
damper).
6.8.3
Ignition failure
If the burner does not ignite, it locks out within 3s after the gas
valve opens, and the post-purging phase starts lasting 17s, i.e.
122s from TL closure.
Burner flame goes out during operation
If the flame goes out during operation, the burner will lock out
within 1s.
6.8.4
Final checks (with burner operating)
•
Disconnect a wire of the minimum gas pressure switch:
•
Open TL remote control:
•
Open TS remote control:
the burner must stop
•
Disconnect the P shared wire of the maximum gas pressure
switch:
•
Disconnect the P shared wire of the air pressure switch:
•
Disconnect the electrical connections of the ionisation probe:
the burner must stop in lockout
•
Make sure that the mechanical locking systems on the
various adjustment devices are fully tightened.
34
GB
20156544
Fig. 39
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