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ModulATiNG GAS vAlvE
11 ModulATiNG GAS vAlvE
11.1 function
The Modulating gas valve A in Figure 11.1 controls the gas inflow
to the boiler burner.
figure 11.1
A
By means of an electric command given to the on-off operators
the passage of the gas through the Modulating gas valve can be
opened or closed.
By means of an electric command given to the modulation opera-
tor the pressure can be varied and therefore the gas flow rate to
the burner (modulation). The modulation operator has mechani-
cal components which allow the adjustment of the minimum and
maximum pressure exiting the valve.
11.2 Nomenclature of the parts
- (figure 11.2)
1
Minimum gas pressure adjustment
2
Maximum gas pressure adjustment
3
Modulation operator’s electric connectors
4
On-off operators electric connector
5
On-off operators
6
Gas valve inlet pressure test point
7
Gas valve outlet pressure test point
8
Modulation operator
figure 11.2
7
8
6
4
5
1
2
3
11.3 Adjustment
for the pressure values refer to the Technical data section
of the user manual and installation instructions.
Warning: isolate the boiler from the mains electrici-
ty supply before removing any covering or compo-
nent.
1 Remove the case panels and the sealed chamber lid (section
"Body panels" page 5).
2 Open the gas valve inlet pressure test point (6 in Figure 11.2)
at the valve input, connect a suitable pressure gauge and
check the gas pressure of the supply network.
3 Remove the gauge and close the pressure test point 6.
4 Open the gas valve outlet pressure test point (7 in Figure
11.2) and connect the gauge;
figure 11.3
b
C
