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6.5
Burner starting (gas operation)
It is advisable to first set the burner for operating
on oil and then for gas.
Execute the fuel exchange when the burner is off.
WARNING
Close the control devices and set switch 1)(Fig. 36) to "MAN".
As soon as the burner starts check the direction of rotation of the
fan blade, looking through the flame inspection window 26)(Fig. 6
at page 13).
Make sure that the lamps or testers connected to the solenoids,
or pilot lights on the solenoids themselves, indicate that no volt-
6.6
Burner firing (gas operation)
Having completed the checks indicated in the previous heading,
the burner should fire. If the motor starts but the flame does not
appear and the control box goes into lock-out, reset and wait for
a new firing attempt.
If firing 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 firing delivery.
6.7
Burner calibration (gas operation)
The optimum calibration of the burner requires an analysis of the
flue gases at the boiler outlet.
Adjust successively
–
Firing output
–
MAX burner output
–
MIN burner output
–
Intermediate outputs
–
Air pressure switch
–
Maximum gas pressure switch
–
Minimum gas pressure switch
6.7.1
Firing output
According to EN 676 Regulations:
Burners with MAX output up to 120 kW
Firing can be performed at the maximum operation output level.
Example:
–
max. operation output
–
max. firing output
Burners with MAX output above 120 kW
Firing must be performed at a lower output than the max. opera-
tion output. If the firing output does not exceed 120 kW, no calcu-
lations are required. If firing output exceeds 120 kW, the
regulations prescribe that the value be defined according to the
control box safety time "ts":
–
for ts = 2s, firing output must be equal to or lower than 1/2 of
max. operation output;
–
for ts = 3s, firing output must be equal to or lower than 1/3 of
max. operation output.
Example:
MAX operation output of 600 kW.
Firing output must be equal to or lower than:
–
300 kW con ts = 2s
–
200 kW con ts = 3s
In order to measure the firing output:
remove the UV cell 17)(Fig. 6 at page 13) (the burner will fire
and then go into lock-out after the safety time has elapsed).
Start-up, calibration and operation of the burner
: 120 kW
: 120 kW
age is present. If voltage is present, then immediately stop the
burner and check electrical connections.
D791
The arrival of gas at the sleeve is indicated by the U-type manom-
eter (Fig. 35).
Once the burner has fired, now proceed with global calibration
operations.
Perform 10 firings with consecutive lock-outs.
On the meter read the quantity of gas burned. This quantity
must be equal to or lower than the quantity given by the for-
mula:
3
/h (max. burner delivery)
Sm
360
Example for G 20 (9.45 kWh/Nm
max. operation output: 600 kW corresponding to 60 Sm
After 10 firings with lock-outs, the delivery read on the meter must
be equal to or lower than: 60 : 360 = 0.166 Sm
6.7.2
MAX burner output
Max. output of the burner must be set within the firing rate range
shown on pag. 11.
In the above instructions we left the burner running in MIN. output
operation. Now press button 2)(Fig. 36) "increase output" and
keep it pressed until the servomotor has opened the air gate
valve and the gas butterfly valve.
Gas calibration
Measure the gas delivery at the meter.
A guideline indication can be calculated from the Tab. N at
page 24, simply read off the gas pressure on the U-type manom-
eter, see Fig. 35 at page 28, and follow the instructions on
pag. 24.
–
If delivery needs to be reduced, diminish outlet gas pressure
and, if it is already very low, slightly close adjustment valve
VR.
–
If delivery needs to be increased, increase outlet gas pres-
sure.
Adjusting air delivery
Progressively adjust the end profile of cam 4)(Fig. 37) by turning
the screws 7).
–
Turn the screws clockwise to increase air delivery.
–
Turn the screws counter-clockwise to reduce air delivery.
29
GB
1
2
3
):
3
3
.
Fig. 36
/h.
20034293
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