Operation Sequence Of The Burner; Final Checks - Riello RL 70/M Installation, Use And Maintenance Instructions

7.5

Operation sequence of the burner

7.5.1 Burner starting
0 s : Control device TL closes, the motor starts.
The pump 3) sucks the fuel from the tank through the
piping 1) and the filter 2) and pumps it under pres-
sure 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 de-energized solenoid valves 8) - 9) - 16) -
17) close the passage to the nozzle.
6 s : Servomotor starts: 130° rotation to right, until contact
is made on cam I)(Fig. 31 on page 26).The air gate
valve is positioned on MAX. output.
48 s : Pre-purge stage with air delivery at MAX. output.
85 s : Servomotor rotates to left until contact is made on
cam III) (Fig. 31 on page 26).
121 s : Air gate valve and pressure regulator are positioned
on MIN output.
123 s : Ignition electrode strikes a spark.
128 s : Solenoid valves 8) - 9) - 16) open; the fuel passes
through the piping 10) and filter 11), and enters the
nozzle.
A part of the fuel is then sprayed out through the
nozzle, igniting when it comes into contact with the
spark: flame at a low output level, point A; the rest of
the fuel passes through piping 12 at the pressure
adjusted by the regulator 13, then, through piping 7),
it goes back into the tank.
131 s : The spark goes out.
153 s : The starting cycle ends.
7.5.2 Steady state operation (Fig. 34)
Burner without output regulator RWF
At the end of the starting cycle, the servo-motor control then
passes to load control TR for boiler pressure or temperature,
point B.
 If the temperature or pressure is low (and the TR load con-
trol is consequently closed), the burner progressively
increases output up to MAX (section B-C).
 If subsequently the temperature or pressure increases until
TR opens, the burner progressively decreases output down
to MIN (section D-E). And so on.
 The burner locks out when demand for heat is less than the
heat supplied by the burner in the MIN output (section F-G).
Load control TL opens. The servomotor returns to the 0°
angle limited by contact with cam II)(Fig. 31 on page 26).
The gate valve closes completely to reduce thermal disper-
sion to a minimum.
Every time output is changed, the servomotor automatically mod-
ifies gas oil delivery (pressure regulator) and air delivery (fan gate
valve).
Burner with output regulator RWF
See the handbook enclosed with the regulator.
20166443
Start-up, calibration and operation of the burner
M
123
VS VF VR
128
48 85
MAX
M
MIN
0
6
2
1
0
128
0 sec
20169283
7.5.3 Firing failure
If the burner does not fire, it goes into lock-out within 2.5 s of the
opening of the light oil valve and the pre-purging phase starts and
lasts 15 seconds.
7.5.4 Undesired shut-down during operation
If the flame should go out for accidental reasons during operation,
the burner will lock out in 1 s.
7.6

Final checks

 Obscure the flame sensor and switch off the control
devices: the burner should start and then lock-out about 5 s
after starting.
 Illuminate the flame sensor and switch off the control
devices: burner should go into lock-out.
 Obscure the flame sensor while the burner is operating:
flame should go out and burner lock out within 1 s.
 Switch off control device TL followed by control device
TS while the burner is operating: the burner should stop.
Make sure that the mechanical locking systems
on the various adjustment devices are fully
tightened.
WARNING
28 GB
131
121
C D
A B E
153
131
F
G
Fig. 34