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6.8
Burner operation
6.8.1
Burner start-up
0s:
TL thermostat/pressure switch closes.
2s:
Start of electrical control box programme. Servomotor
starts: turn 90° to the left, i.e. until the contact on cam I in-
tervenes (Fig. 24 on page 24).
26s:
The air damper arrives to the MAX. output position.
Fan motor starts up.
Start of the pre-purging phase.
57s:
the servomotor rotates towards the right, as far as the an-
gle set on cam III (Fig. 24 on page 24) for the MIN output.
77s:
The air damper and gas butterfly valve assume the MIN
output position (with cam III)(Fig. 24 on page 24) at 15°.
92s:
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 out-
put level, point A.
Delivery is then progressively increased, with the valve
VR opening slowly up to MIN. output, point B.
94s:
The spark goes out.
118s: The starting cycle comes to an end.
6.8.2
Operation
Burner without modulating operation kit
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.
(The electrical control box still continues to check the presence of
the flame and the correct position of the air and gas pressure
switches).
–
If the temperature or the pressure is low, the reason why the
thermostat/pressure switch TR is in the output request posi-
tion, the burner progressively increases the output up to the
MAX value (section C-D).
–
If, then, the temperature or the pressure increases up to the
TR switching, the burner gradually decreases the output
down to the MIN value, (section E-F). The sequence repeats
endlessly.
–
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 re-
turns to angle 0°. The air damper closes completely to reduce
heat losses to a minimum.
Burner with modulating operation kit
See manual enclosed with the adjuster.
6.8.3
Ignition failure
If the burner does not switch on, it goes into lockout within 3s of
the gas valve opening.
6.8.4
Burner flame goes out during operation
If the flame should accidentally go out during operation, the burn-
er will lock out within 1s.
20098687
Start-up, calibration and operation of the burner
D3857
D799
In the event the burner stops, in order to prevent
any damage to the installation, do not unblock the
burner more than twice in a row.
WARNING
If the burner locks out for a third time, contact the
customer service.
In the event there are further lockouts or faults
with the burner, the maintenance interventions
must only be carried out by qualified, authorised
personnel, in accordance with the contents of this
DANGER
manual and in compliance with the standards and
regulations of current laws.
28
GB
STANDARD IGNITION
(no. = seconds from instant 0)
IGNITION FAILURE
Fig. 31
Fig. 32
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