21
2916089
GB
Burner calibration
7.2.1
Burner starting (Fig. 26) - (Fig. 27)
Starting phases with progressive time intervals shown in sec-
onds:
Control device TL closes.
After about 3s:
0 s:
The control box starting cycle begins.
2 s:
The fan motor starts.
3 s:
The ignition transformer is connected.
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 piping 5) - 7). The screw 6) closes the by-pass heading
towards suction and the solenoid valves 8) - 11) - 16), de-
energized, close the passage to the nozzles.
The hydraulic cylinder 15), piston A, opens the air gate
valve: pre-purging begins with the 1st stage air delivery.
22 s:
Solenoid valves 8) and 16) open 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. This is the 1st stage flame.
29 s:
The ignition transformer switches off.
36 s:
If the control device TR is closed or has been replaced
by a jumper wire, the 2nd stage solenoid valve 11) is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 device 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), piston B, that opens the fan air gate valve in the 2nd
stage.
The starting cycle comes to an end.
7.2.2
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
control device TR opens, solenoid valve 11) closes, and the
burner passes from the 2nd to the 1st stage of operation.
When the temperature or pressure decreases until the con-
trol device TR closes, solenoid valve 11) opens, and 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 solenoid valves
8)-16) close, the flame immediately goes out. The fan's air
gate valve closes completely.
Systems not equipped with control device TR (jumper wire
installed)
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), piston B, is discharged into the return piping 7).
7.2.3
Firing failure
If the burner does not fire, it goes into lock-out within 5 s of the
opening of the 1st stage valve and 30 s after the closing of control
device TL.
The control box red pilot light will light up.
7.2.4
Undesired shutdown 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.
7.2.5
Final checks
Darken the flame sensor and switch on the control
devices:
the burner should start and then lock-out about 5 s
after opening of the 1st stage operation valve.
Illuminate the flame sensor and switch on the control
devices:
the burner should start and then go into lock-out
after about 10 s.
Darken the flame sensor while the burner is in 2nd
stage operation, the following must occur in sequence:
flame extinguished within 1 s, pre-purging for about 20 s,
sparking for about 5 s, burner goes into lock out.
Switch off control device TL followed by control device
TS while the burner is operating:
the burner should stop.
D3315
Fig. 27
