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Start-up, calibration and operation of the burner
5
5.3
Burner start-up
Feed electricity to the burner via the disconnecting switch on
the boiler panel.
Close the thermostats/pressure switches and turn the switch
of Fig. 27 to position "MAN".
Make sure that the lights or testers connected to
the solenoids, or the pilot lights on the solenoids
themselves, indicate that no voltage is present.
DANGER
If voltage is present, stop the burner immediately
and check the electrical wiring.
As soon as the burner starts, check the direction of rotation of
the fan blade, looking through the flame inspection window.
5.4
Burner ignition
Having completed the checks indicated in the previous head-
ing, 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 reach-
ing the combustion head within the safety time period of 3
seconds. In this case increase gas ignition delivery.
The arrival of gas to the pipe coupling is shown by the pres-
sure gauge.
Once the burner has ignited, proceed with the global adjust-
ment of the burner.
5.5
Burner adjustment
The optimum adjustment of the burner requires an analysis of
flue gases at the boiler outlet.
Adjust in sequence:
Ignition output
Maximum output
Minimum output
Intermediate outputs between Min. and Max
Air pressure switch
Maximum gas pressure switch
Minimum gas pressure switch
6461
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D8694
Fig. 26
20
Ignition output
According to EN 676 standard:
Burners with MAX output up to 120 kW
Ignition can occur at the maximum operation output level.
Example:
max. operation output: 120 kW
max. ignition output: 120 kW
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
required. If ignition output exceeds 120 kW, the regulatory
standard sets that the value be defined according to the con-
trol box safety time "ts":
for "ts" = 3s, ignition output must be equal to or less than 1/3
of the max. operation output.
Example
MAX operation output of 450 kW.
The ignition output must be equal to or less than 150 kW with
ts = 3s.
In order to measure the ignition output:
disconnect the plug-socket 6)(Fig. 5) on the ionisation
probe cable (the burner will fire and then go into lockout
after the safety time has elapsed);
perform 10 ignitions with consecutive lockouts;
on the meter, read the quantity of gas burned:
this quantity must be equal to, or lower than, the quantity
given by the formula, for ts = 3s:
Qa (max. burner delivery) x n x ts
Vg =
Vg: volume supplied in ignitions carried out (Sm
3
Qa: ignition delivery (Sm
/h)
n: number of ignitions (10)
ts: safety time (sec)
Example for gas G 20 (9.45 kWh/Sm
ignition output 150 kW
3
corresponding to 15.87 Sm
/h.
After 10 ignitions with their lockouts, the delivery indicated on
the meter must be equal to or less than:
15.87 x 10 x 3
Vg =
3600
Maximum output
The maximum burner output must be set within the firing rate
range shown on page 7. In the above instructions we left the
burner running at the MIN output.
Now press the button 2)(Fig. 27) "output increase", and keep
it pressed until the servomotor has opened the air damper
and the gas butterfly valve.
1
D791
GB
3600
3
)
3
):
3
= 0.132 Sm
2
Fig. 27
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