20148049
32
GB
Start-up, calibration and operation of the burner
6.9
Burner adjustment (gas)
The optimum adjustment of the burner requires an analysis of
flue gases at the boiler outlet.
Adjust in sequence:
1
Ignition output
2
Maximum output
3
Minimum output
4
Intermediate outputs between the two
5
Air pressure switch
6
Maximum gas pressure switch
7
Minimum gas pressure switch
6.9.1
Ignition output
According to standard 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
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
control box safety time "ts":
for "ts" = 3s, ignition output must be equal to or lower than 1/3
of max. operation output.
Example
MAX operation output of 600 kW.
Ignition output must be equal to or lower than:
•
300 kW with ts = 2 s.
•
200 kW with ts = 3 s.
In order to measure the ignition output:
remove flame sensor 11)(Fig. 7 on page 12) (the burner
starts and locks out after the safety time);
perform 10 consecutive ignitions with lockouts;
read the quantity of burned gas on the meter:
this quantity must be equal to, or lower than, the quantity
given by the formula:
Example
for G 20 gas (9.45 kWh/Sm
3
):
Max. operation output: 600 kW corresponding to 63.5 Sm
3
/h.
After 10 ignitions with a lockout, the delivery indicated on the
meter must be equal to or lower than: 63.5: 360 = 0.176 Sm
3
Air adjustment
The air is adjusted by changing the angle of cam III) (Fig. 35 on
page 29) and by using the selector 2)(Fig. 36 on page 30).
To adjust the cam of the servomotor, see Fig. 35 on page 29.
6.9.2
Maximum output
The MAX output must be set within the firing rate indicated in
Fig. 3 on page 10.
In the above instructions we left the burner running at the MIN
output.
Now press the “increase output” button 2)(Fig. 36), and keep it
pressed until the servomotor has opened the air damper and the
gas butterfly valve.
Adjustment of gas delivery
Measure the gas delivery on the meter.
A rough indication can be obtained from Tab. L on page 26, just
read the gas pressure on the "U" pressure gauge (see Fig. 37 on
page 31) and follow the indications.
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.
Air adjustment
The air is adjusted by varying the angle of cam I) (Fig. 35 on
page 29) and by using the selector 2)(Fig. 36 on page 30).
To adjust the cam of the servomotor, see Fig. 35 on page 29.
Key (Fig. 38)
1
Servomotor
2
Servomotor 1) - cam 4): fastened
3
Servomotor 1) - cam 4): unfastened
4
Variable profile cam
5
Screws for adjusting the adjustable profile
6
Screws for fixing adjustment
7
Screws for adjusting the end profile
8
Gas butterfly valve graduated sector
9
Index of graduated sector 8)
Sm
3
/h
(max. burner delivery)
360
Fig. 38
D891
