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7.9
Burner operation
7.9.1
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 36.
• 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 1st stage air delivery.
The pump 3) sucks the fuel from the tank through the piping 1)
and the filter 2) and pumps it under pressure to delivery. The
piston 4) rises and the fuel returns to the tank through the pip-
ing 5) - 7). The screw 6) closes the by-pass heading towards
suction and the solenoid valves 8) and 11), de-energized,
close the passage to the nozzles.
• After 25 sec.:
Solenoid valve 8) openes and the fuel passes through the pip-
ing 9) and filter 10) and is then sprayed out through the nozzle,
igniting when it comes into contact with the spark. This is the
1st stage flame.
• After 30 sec.:
The ignition transformer switches off.
If the control device TR is closed or has been replaced by a
jumper wire, the 2nd stage solenoid valve 11) is opened and
the fuel enters the valve 12) and raises the piston which opens
two passages: one to piping 13), filter 14), and the 2nd stage
nozzle, and the other to the cylinder 15) that opens the fan air
gate valve in the 2nd stage.
• After 39 sec.:
The starting cycle comes to an end.
7.9.2
Steady State Operation
System equipped with one control device TR.
Once the starting cycle has come to an end, the command of the
2nd stage solenoid valve passes on to the control device TR that
controls boiler temperature or pressure.
– When the temperature or the pressure increases until the con-
trol device TR opens, the burner passes from the 2nd to the
1st stage of operation.
– When the temperature or pressure decreases until the control
device TR closes, the burner passes from the 1st to the 2nd
stage of operation, and so on.
– The burner stops when the demand for heat is less than the
amount of heat delivered by the burner in the 1st stage. In this
case, the control device TL opens, and the solenoid valve 8)
closes, the flame immediately goes out. The fan's air gate
valve remains in the 1st stage position.
Systems not equipped with control device TR (which has
been replaced by a jumper)
The burner is fired as described in the case above. If the temper-
ature or pressure increase until control device TL opens, the
burner shuts down (Section A-A in the diagram).
When the solenoid valve 11) de-energizes, the piston 12) closes
the passage to the 2nd stage nozzle and the fuel contained in the
cylinder 15) is discharged into the return piping 7).
Start-up, calibration and operation of the burner
31
GB
D429
D2462
Fig. 31
Fig. 32
20033097
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