11
BURNER CALIBRATION
The optimum calibration of the burner requires
an analysis of the flue gases at the boiler outlet.
Adjust successively:
1 - Output upon ignition (minimum)
2 - Max. burner output
3 - Intermediate outputs between Min. and Max.
4 - Air pressure switch
5 - Minimum gas pressure switch
DETERMINATION OF OUTPUT UPON IGNI-
TION (MINIMUM)
According to the regulation EN 676.
Burners with MAX output up to 120kW
Ignition can be performed at the maximum oper-
ation output level. Example:
• max. operation output
: 120 kW
• max. ignition output
: 120 kW
Burners with MAX output above 120kW
Ignition must be performed 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 regulations prescribe 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 450 kW.
The ignition output must be equal to, or less
than, 150kW with ts = 3s
In order to measure the ignition output:
- disconnect the plug-socket 24)(A)p.4 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 lock-
outs.
- Read, on the meter, the quantity of gas
burned.
This quantity must be equal to, or lower than,
the quantity given by the formula, for ts = 3s:
Vg:
volume supplied in ignitions carried out
(Sm
3
)
Qa:
ignition output (Sm
3
/h)
n:
number of ignitions (10)
ts
: safety time (sec)
Example
for gas G 20 (9.45 kWh/Sm
3
):
ignition output 150 kW
corresponding to 15.87 Sm
3
/h.
After 10 ignitions with lockout, the output indi-
cated on the meter must be equal to, or less
than:
1 - OUTPUT UPON IGNITION (MINIMUM)
Min output must be selected within the firing rate
range shown on page 5.
Press the button 2)(A) “output reduction”, and
keep it pressed until the servomotor has closed
the air damper and the gas butterfly valve at 15°
(adjustment made in the factory).
Adjusting gas delivery
Measure the gas delivery at the meter.
- If it is necessary to reduce it, reduce slightly
the angle of cam III fig.(B)p.12 with small, reg-
ular movements, i.e. bring it from an angle of
15° to 13° - 11°....
- If it is necessary to increase it, press slightly
the button “output increase” 2)(A) (open by
10-15° the gas butterfly valve), increase the
angle of cam III fig.(B)p.12 with small, regular
movements, i.e. bring it from an angle of 15°
to 17° - 19°....
Then press the button “output reduction” until
the servomotor is in the position of minimum
opening, and measure the gas output.
(A)
D3833
Vg =
3600
Qa
(max. burner output)
x n x ts
Vg =
3600
15.87 x 10 x 3
= 0.132 Sm
3
