35
20148049
GB
Start-up, calibration and operation of the burner
6.11
Operation sequence of the burner (gas)
6.11.1 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. 35 on page 29).
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. 35 on page 29) for the MIN output.
•
112s: The air damper and the gas butterfly valve reach the
MIN output position (with cam III)(Fig. 35 on page 29)
at 30°.
•
113s: Ignition electrode strikes a spark.
•
119s: The safety valve VS and the adjustment valve VR
open (quick opening). The flame ignites with a small
output - point A.
The output gradually increases, and the VR valve
slowly opens, until the MIN output is reached - point B.
•
122s: The spark goes out.
•
135s: The start-up cycle ends.
6.11.2 Steady state operation
Burner without output regulator RWF
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.
•
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, the servomotor returns to angle 0°
limited by the contact of cam II Fig. 35 on page 29. 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).
Burner with output regulator RWF
See the manual supplied with the regulator.
6.11.3 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 18s, 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.
Fig. 43
D3202
Fig. 44
20159585
