Servomotor; Burner Start-Up; Burner Ignition; Burner Adjustment - Riello RS 55/M BLU Instrucciones De Instalación, Uso Y Mantenimiento

6.3

Servomotor

The servomotor (Fig. 25) provides simultaneous adjustment for
the air damper, by means of the variable profile cam, and the gas
butterfly valve.
The angle of rotation of the servomotor is equal to the angle on
the graduated sector controlling the gas butterfly valve.
The servomotor rotates by 90° in 24 seconds.
Do not alter the factory setting for the 4 cams; sim-
ply check that they are set as indicated below:
WARNING
Cam I : 90°
Limits rotation toward maximum position. When the burner is at
MAX output, the gas butterfly valve must be fully open: 90°.
Cam II: 0°
Limits rotation toward minimum position.
When the burner is shut down, the air damper and gas butterfly
valve must be closed: 0°.
6.4

Burner start-up

Switch off the remote controls and place the switch 1)(Fig. 26) to
"MAN" position.
As soon as the burner starts, check the direction of rotation of the
fan blade, looking through the flame inspection window 18)(Fig. 5
on page 11).
Make sure that the lights or testers connected to the solenoids, or
the pilot lights on the solenoids themselves, indicate that no volt-
age is present.
If voltage is present, stop the burner immediately and check the
electrical connections.
6.5

Burner ignition

Having completed the checks indicated in the previous heading,
ignition of the burner should be achieved.
If the motor starts but the flame does not appear and the control
box goes into lockout, reset and wait for a new ignition attempt.
If ignition is still not achieved, it may be that gas is not reaching
the combustion head within the safety time period of 3 seconds.
In this case, increase gas ignition delivery.
6.6

Burner adjustment

The optimum adjustment of the burner requires an analysis of
flue gases at the boiler outlet.
Adjust in sequence:
–

Ignition output (minimum)

–

MAX output

– Intermediate outputs between Min. and Max.
– Air pressure switch
– maximum gas pressure switch
– minimum gas pressure switch
Start-up, calibration and operation of the burner
Cam III: 20°
Adjusts the ignition position and the MIN output.
Cam IV:
integrated to cam III.
D791
The arrival of gas to the pipe coupling is shown by the pressure
gauge (Fig. 24 on page 22).
Once the burner has ignited, proceed with the global adjustment
of the burner.
6.6.1

Determining ignition output (minimum)

According to EN 676 standard:
Burners with MAX output above 120 kW
Ignition must occur at a lower output than the max. operation output.
If ignition output does not exceed 120 kW, no calculations are re-
quired. If ignition output exceeds 120 kW, the regulatory standard
sets that the value must be defined according to the control box
safety time "ts":
– for "ts" = 2s, ignition output must be equal to or less than 1/2
of the max. operation output;
– for "ts" = 3s, ignition output must be equal to or less than 1/3
of the max. operation output.
23 GB
D790
1 2
Fig. 25
Fig. 26
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