Burner Operation; Oil Pressure Switch - Riello Burners RL 190/M Installation, Use And Maintenance Instructions

(A)

BURNER OPERATION

BURNER STARTING (A) - (B)
• Operating control closes, the motor starts.
The pump 3) draws the fuel from the tank through the
piping 1) and pumps it under pressure for 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 sole-
noid valves 2) - 8) - 9) close the passage to the nozzle.
• Servomotor starts: 130° rotation to right, until contact is
made on cam 1. The air damper is positioned on MAX.
output.
• Pre-purge stage with air delivery at MAX. output.
• Servomotor rotates to left until contact is made on cam
3.
• Air damper and pressure regulator are positioned on
MIN output.
• Ignition electrodes spark.
• Solenoid valves 2) - 8) - 9) 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 noz-
zle, igniting when it comes into contact with the spark:
flame at a low output level; the rest of the fuel passes
through piping 12 at the pressure adjusted by the regu-
lator 13, then, through piping 7), it goes back into the
tank.
• The spark goes out.
• The starting cycle ends.
STEADY STATE OPERATION
At the end of the starting cycle, the servo-motor control
then passes to load control for boiler pressure or tem-
perature.
• If the temperature or pressure is low (and the load con-
trol is consequently closed), the burner progressively
increases output up to MAX.
• If subsequently the temperature or pressure increases
until the load control opens, the burner progressively
decreases output down to MIN.
• The burner shuts down when demand for heat is less
than the heat supplied by the burner in the MIN output.
The servomotor returns to the 0° angle limited by con-
tact with cam 2. The air damper closes completely to
D2444
reduce thermal dispersion to a minimum.
Every time output is changed, the servomotor automati-
cally modifies oil delivery (pressure regulator) and air
delivery (fan damper).
FIRING FAILURE
If the burner does not fire, it goes into lock-out within 5 s
of the opening of the light oil valve.
FLAME FAILURE
If the flame should go out for accidental reasons during
operation, the burner will lock out in 1 s.

OIL PRESSURE SWITCH

The oil pressure switch 15)(A) page 4 is factory set to
43.5 PSI (3 bar). If the oil pressure reaches this value in
the return piping, the pressure switch stops the burner.
Burner starts again automatically if the pressure goes
down under 43.5 PSI (3 bar) after burner shut down. If a
loop circuit with Px pressure feeds the burner, the pres-
sure switch should be adjusted to Px + 43.5 PSI.
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