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6.8
Operation sequence of the burner
6.8.1
Burner start-up
T0:
0 s. - Closure of thermostat/pressure switch TL.
T1:
2 s. - Start of electrical flame control programme.
Fan motor starts up, servomotor starts up, the pre-purging
phase starts. The servomotor rotates to the right by 90°,
i.e. until the contact intervenes on the cam 1)(Fig. 26 on
page 24).
T2:
34 s. - The air damper arrives at the MAX. output posi-
tion.
T3:
58 s. - The servomotor rotates towards the left until the
angle set on the cam 3).
T4:
85 s. - The air damper arrives on the MIN. power position
or ignition position.
T5:
89 s. - The ignition electrode strikes a spark. The safety
valve VS opens, along with the adjustment valve VR.
The flame is ignited at a low output level, point A.
Delivery is then progressively increased, with the valve
VR opening slowly up to MIN. output, point B.
T6:
91 s. - The spark goes out.
T7:
99 s. - The control value box starting cycle ends.
6.8.2
Operation
Burner without the RWF... output regulator (See 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
flame control continues to check the presence of the flame and
the correct position of the air and gas maximum pressure switch-
es).
–
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 servomotor re-
turns to angle 0° limited by the contact of the cam 2)(Fig. 26
on
The air damper closes completely to reduce heat losses to a
minimum.
For every change of output, the servomotor will automatically
change the gas output (butterfly valve), the air output (fan damp-
er) and the air pressure.
Burner with the RWF ... output regulator (See kit)
See manual enclosed with the adjuster.
6.8.3
Ignition failure
If the burner does not fire, it goes into lockout within 3 seconds
after the gas valve opens or 91 seconds after the TL closes.
6.8.4
Burner flame goes out during operation
If the flame should go out during operation, the burner will lockout
within 1s.
Start-up, calibration and operation of the burner
page 24).
(n° = seconds from instant 0)
27
GB
Normal ignition
Ignition failure
20073942
Fig. 30
20073943
Fig. 31
20160598
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