2750
7
GB
4.3 SETTING OF THE AIR DAMPER ACTUATOR
Check that cams I and V are respectively set at 20°
and 90°.
I CAM
The
I
cam controls the air for the 1
st
stage flame (2, fig. 2).
The cam must be adjusted on decrease (damper closing)
by adjusting the micrometer screw.
The definitive position is obtained after 2
nd
stage adjust-
ment.
II CAM
The
II
cam controls the air for the 2
nd
stage flame.
(Reference value 60°, not to exceed 70°).
Do not modify this setting for any reason.
The regulation of airflow at 2
nd
stage is carried out by oper-
ating the air damper (1, fig. 2).
The
III
cam controls the opening of the gas valve at 2
nd
stage and must precede the
II
cam by at least 15°.
Warning:
For power adjustment at 1
st
and 2
nd
stage, apply the fol-
lowing indications:
– the power ratio between 1
st
and 2
nd
stage must be 1 : 2
at a maximum, if the above ratio is exceeded, valve seal
control must be used;
– in any case, the minimum burner power at 1
st
stage
must not be less than the firing rate range.
4.4 COMBUSTION CHECK
It is advisable to set the burner according to the type of gas used and following the indications of the table:
IONIZATION CURRENT
The minimum current necessary for the control
box operation is 3 µA.
The burner normally supplies a higher current
value, so that no check is needed. However, if
you want to measure the ionization current, you
must open the connector fitted to the red wire
and insert a microammeter.
EN 676
AIR EXCESS:
max. output
λ
≤
1.2
– min. output
λ
≤
1.3
GAS
Theoretical max. CO
2
0 % O
2
Setting CO
2
%
CO
mg/kWh
NO
x
mg/kWh
λ
= 1.2
λ
= 1.3
G 20
11.7
9.7
9.0
≤
100
≤
170
G 25
11.5
9.5
8.8
≤
100
≤
170
G 30
14.0
11.6
10.7
≤
100
≤
230
G 31
13.7
11.4
10.5
≤
100
≤
230
Micrometric screws
D1777
Op
en
+
Shut
–
Fig. 2
2
1
E9085
ATTENTION
PAUSE - FIRST STAGE
SECOND STAGE
Probe
Connector
Terminal board
of control-box
D5006
10
