25
3.4.2
Minimum pressure adjustment V4600N
To set the minimum pressure, proceed as follows (Fig. 31):
– withdraw the modulator (4);
– set the knob of the D.H.W. potentiometer to the maxi-
mum value (3, Fig. 32);
– ignite the boiler by operating the switch and open the
D.H.W. tap;
– turn the screw (3, Fig. 31) to arrive at the minimum
pressure value given in Table 8: to reduce the pressu-
re, turn the screw counterclockwise; to increase the
pressure, turn it clockwise;
– replace the modulator (4) in position;
– operate the main switch a number of times, keeping
the D.H.W. tap open all the time, and check that the
pressure corresponds to the values given in Table 8;
– Fix the modulator with its retaining spring.
3.4.3
Maximum pressure adjustment 837 TANDEM
To set the maximum pressure, proceed as follows (Fig.
31/a):
– connect the pressure column or a pressure gauge to
the pressure inlet downstream of the gas valve;
– remove the plastic cap (1);
– set the knob of the D.H.W. potentiometer to the maxi-
mum value (3, Fig. 32);
– ignite the boiler by operating the switch and open the
hot water tap;
– using a ø 10 spanner, turn the nut (3) to arrive at the
maximum pressure value given in Table 8: to reduce
the pressure, turn the nut counterclockwise; to increa-
se the pressure, turn it clockwise;
– operate the main switch a number of times, keeping
the hot water tap open all the time, and check that the
pressure corresponds to the values given in Table 8.
3.4.4
Minimum pressure adjustment 837 TANDEM
To set the minimum pressure, proceed as follows (Fig.
31/a):
– disconnect the electric power to the modulator;
– set the knob of the D.H.W. potentiometer to the maxi-
mum value and open the hot water tap;
– ignite the boiler by operating the switch and turn the
screw (2) keeping locked the nut (3) to arrive at the
minimum pressure value given in Table 8: to reduce
the pressure, turn the screw counterclockwise; to
increase the pressure, turn it clockwise;
– operate the main switch a number of times, keeping
the D.H.W. tap open all the time, and check that the
pressure corresponds to the values given in Table 8;
– restore electric power to the modulator and replace
the plastic cap (1) in position.
3.4.5
Minimum pressure adjustment VK4105M
To set the minimum pressure, proceed as follows (Fig. 31/b):
– connect the pressure column or a pressure gauge to
the pressure inlet downstream of the gas valve;
– disconnect the electric power and remove the plastic
cap on the modulator (1);
– set the knob of the D.H.W. potentiometer to the maxi-
mum value (3, Fig. 32);
– ignite the boiler by operating the switch and open the
D.H.W. tap at a high flow rate;
– using a ø 9 spanner, turn the nut (2) to arrive at the
minimum pressure value given in Table 8: to reduce
the pressure, turn the nut counterclockwise; to increa-
se the pressure, turn it clockwise;
– operate the main switch a number of times, keeping
the D.H.W. tap open all the time, and check that the
pressure corresponds to the values given in Table 8;
– restore electric power to the modulator.
KEY
1 Maximum pressure
adjusting union
2 Lockin nut M13
3 Minimum pressure
adjusting screw
4 Modulator 24 V
Burner Modulator
Burner Modulator
Type of gas
max. pressure
current
min. pressure current
mbar
mA
mbar
mA
Methane - G20
10 - 11
130
2
0
L.P.G. - G30
28
150
7
0
L.P.G. - G31
35
150
7
0
TABLE 8
Fig. 31
Fig. 31/b
KEY
1 Plastic cap
2 Minimum pressure
adjusting nut
3 Maximum pressure
adjusting nut
4 Modulator 24 V
LEGENDA
1
Plastic cap
2
Minimum pressure
adjusting screw
3
Maximum pressure
adjusting nut
Fig. 31/a
