20159575
22
GB
Start-up, calibration and operation of the burner
6.4
Burner start-up
Turn off the remote controls and set the switch 1)(Fig. 27) to
“MAN”.
As soon as the burner starts, check the direction of rotation of the
fan impeller, looking through the flame inspection window 18)
(Fig. 5 on page 11).
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. The arrival of gas at
the pipe coupling is indicated by the U-type pressure gauge
(Fig. 25 on page 21).
Once the burner has fired, now proceed with global calibration
operations.
6.6
Burner adjustment
The optimum adjustment of the burner requires an analysis of
flue gases at the boiler outlet.
Adjust in sequence:
1
Output upon ignition
2
Maximum output
3
Minimum output
4
Intermediate outputs between the two
5
Air pressure switch
6
Minimum gas pressure switch
6.6.1
Output upon ignition
According to EN 676.
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 out-
put.
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 be defined according to the control box safety
time “ts”:
–
for “ts” = 2s, ignition output must be equal to or lower than 1/
2 of max. operation output;
–
for “ts” = 3s, ignition output must be equal to or less than 1/3
of the max. operation output.
Example:
MAX operation output of 600 kW. Ignition output must be equal
to or lower than:
–
300 kW con ts = 2s
–
200 kW con ts = 3s
In order to measure the ignition output:
disconnect the plug-socket 23)(Fig. 5 on page 11) on the
ionisation probe cable (the burner will fire and then go into
lockout after the safety time has elapsed);
perform 10 consecutive ignitions with 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:
Example
for G 20 gas (10 kWh/Nm
3
):
max. operation output of 600 kW
corresponding to 60 Nm
3
/h.
After 10 ignitions with their lockouts, the delivery indicated on the
meter must be equal to or less than: 60 : 360 = 0.166 Nm
3
.
6.6.2
Maximum output
The MAX output must be set within the firing rate (Fig. 2 on
page 9).
In the above instructions we left the burner running at the MIN
output.
Now press the “increase output” button 2)(Fig. 27), and keep it
pressed until the servomotor has opened the air damper and the
gas butterfly valve to 90°.
Adjustment of gas delivery
Measure the gas delivery on the gas meter.
A rough indication can be obtained from on page 18, just read
the gas pressure on the pressure gauge see Fig. 25 on page 21,
and follow the indication given in on page 18.
–
If delivery needs to be reduced, diminish outlet gas pressure;
if it is already very low, slightly close the VR adjustment valve.
–
If delivery needs to be increased, increase the adjuster outlet
gas pressure.
DANGER
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.
If voltage is present, stop the burner immediately
and check the electrical connections.
Fig. 27
1
2
D791
Nm
3
/h
(max. burner delivery)
360
