33
INS
TALLER
US
ER
MAINTEN
AN
CE TECHNI
CI
AN
3.7 ADJUSTMENT OF THE AIR-GAS
RATIO.
Attention:
the CO
2
verification operations must
be carried out with the casing mounted, while the
gas valve calibration operations must be carried
out with the casing open and disconnecting the
boiler from the power supply.
Calibration of the minimum CO
2
(minimum
heating power).
Enter the chimney sweep phase without with-
drawing domestic hot water and take the se-
lector switches to minimum (turn them in an
anti-clockwise direction until "0" is seen on the
display). To have an exact value of CO
2
in the flue
gases the technician must insert the sampling
probe to the bottom of the sample point, then
check that the CO
2
value is that specified in the
table, otherwise adjust the screw (3 Fig. 3-4) (Off-
Set adjuster). To increase the CO
2
value, turn the
adjustment screw (3) in a clockwise direction and
vice versa to decrease it.
Calibration of the maximum CO
2
(nominal
central heating power).
On completion of the adjustment of the mini-
mum CO
2
keeping the chimney sweep function
active, take the heating selector switch to maxi-
mum (turn it in a clockwise direction until “99”
is seen on the display). To have an exact value of
CO
2
in the flue gases the technician must insert
the sampling probe to the bottom of the sample
point, then check that the CO
2
value is that speci-
fied in the table, otherwise adjust the screw (12
Fig. 3-4) (gas flow rate regulator).
To increase the CO
2
value one must turn the
adjustment screw (12) clockwise for gas valve
8205 and counterclockwise for gas valve 848 and
vice versa is one wants to decrease it.
At every adjustment variation on the screw 12 it
is necessary to wait for the boiler to stabilise itself
at the value set (about 30 sec.).
Magis Victrix ErP
CO
2
at nominal
output
(central heating)
CO
2
at minimum
output
(central heating)
G 20
9.50% ± 0.2
8.95% ± 0.2
G 30
12.30% ± 0.2
11.80% ± 0.2
G 31
10.40% ± 0.2
10.00% ± 0.2
3.8 CHECKS FOLLOWING
CONVERSION TO ANOTHER TYPE
OF GAS.
After making sure that conversion was carried
out with a nozzle of suitable diameter for the
type of gas used and the settings are made at the
correct pressure, check that the burner flame is
not too high or low and is stable (does not detach
from burner);
N.B.:
all boiler adjustment operations must be
carried out by a qualified company (e.g. Author-
ised After-Sales Assistance).
