20098582
24
GB
Start-up, calibration and operation of the burner
An insufficient CO
2
level must also be avoided, since, in addition
to raising costs and falling short of the established range, this can
also be the cause for the generation of a dangerous quantity of
uncombusted hydrocarbons in the flue gas (yellow Bacharach)
and the detachment of the flame upon ignition.
The combustion values measured may be considered reliable
only if there are no entries of air between the burner and the stack
flue gas sampling point. Check for penetration of outside air by
placing a column of smoke near the suspected leak in the seal: if
the smoke column is drawn towards the seal there must be an en-
try of air.
6.4.2
Flue gas temperature
This temperature varies in relation to the delivery generated: the
lower the delivery, the lower the temperature and the higher the
fuel saving. Bear in mind that excessive temperature reduction,
however, gives rise to the formation of condensate.
6.4.3
Combustion chamber pressure
This must correspond to the setting indicated by the boiler man-
ufacturer.
Chamber pressure is lowered with reduced burner delivery and
higher CO
2
levels.
If the combustion chamber pressure is significantly higher than
expected and the burner's delivery is correct, make sure that the
boiler is not dirty, that the flue gas duct is not obstructed, and that
the flue gas stack has been correctly sized.
6.5
Burner operation
6.5.1
Burner starting
–
When the control device TL closes, the control box pro-
grammes the starting phase.
The indications for the start-up cycle are given on page 25.
–
0 sec. time:
The control device TL closes.
–
After 2 sec.:
The motor starts.
–
After 3 sec.:
The ignition transformer is connected. Pre-purging begins
with the max. air delivery.
The pump 3)(Fig. 26) sucks the fuel from the tank through the
piping 1) and the filter 2) and pumps it under pressure to de-
livery. The piston 4) rises and the fuel returns to the tank
through the piping 5) - 7). The screw 6) closes the by-pass
heading towards suction and the solenoid valve 8), de-ener-
gized, closes the passage to the nozzle.
–
After 25 sec.:
Solenoid valve 8) openes and the fuel passes through the
piping 9) and filter 10) and is then sprayed out through the
nozzle, igniting when it comes into contact with the spark.
–
After 30 sec.:
The ignition transformer switches off.
–
After 39 sec.:
The starting cycle comes to an end.
6.5.2
Steady state operation
When the temperature or the pressure increases until the control
device TL opens, the burner shuts down.
6.5.3
Firing failure
If the burner does not fire, it goes into lock-out within 5 seconds
of the opening of the solenoid valve and 30 seconds after the
closing of control device TL.
The control box pilot light will light up.
6.5.4
Undesired shut-down during operation
If the flame goes out during operation, the burner shuts down au-
tomatically within 1 second and automatically attempts to start
again by repeating the starting cycle.
Fig. 25
D2707
Fig. 26
D432