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6.10
Operation sequence of the burner
6.10.1 Burner start-up
0s
TL thermostat/pressure switch closes.
6s
Fan motor starts up. Servomotor starts: 130 rotation to
the right, until contact is made on cam 4).
48s
The air damper is positioned to MAX output.
48s
Pre-purging stage with MAX output air delivery. Duration
32 seconds.
80s
The servomotor rotates to the left up to the angle set on
the cam 2).
112s
The air damper and the gas butterfly valve adopt the MIN
output position (with cam 2).
113s
Ignition electrode strikes a spark.
130s
The safety valve VS opens, along with the adjustment
valve VR (quick opening).
The flame is ignited at a low output level, point A (Fig. 34).
Output is then progressively increased, with the valve
opening slowly up to MIN output, point B (Fig. 34).
122s
The spark goes out.
143s
The control box start-up cycle ends.
6.10.2 Operation
Burner without the output power regulator RWF40
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. 34).
(The electrical control box continues to check the presence of the
flame and the correct position of the air and gas maximum pres-
sure switches).
–
If the temperature or the pressure is low so the thermostat/
pressure switch TR is closed, the burner progressively in-
creases the output up to the MAX value (section C-D).
–
If subsequently the temperature or pressure increases until
TR opens, the burner progressively decreases its output to
the MIN. value (section E-F). The sequence repeats endless-
ly.
–
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 servomo-
tor returns to angle 0 limited by the contact of the 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 damp-
er) and the air pressure (2 shutters in the combustion head).
Burner with the output power regulator RWF40
See manual enclosed with the adjuster.
20061862
Start-up, calibration and operation of the burner
TL
TR
M
VS
VR
M
6.10.3 Burner flame goes out during operation
If the flame should accidentally go out during operation, the burn-
er will lock out within 1s.
6.10.4 Ignition failure
If the burner does not fire (Fig. 35), it goes into lockout within 3 sec.
after the gas valve opens and 122 seconds after the control device
TL closes.
28
GB
NORMAL IGNITION
NO IGNITION
D8339
Fig. 34
D8340
Fig. 35
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