Modulating Gas Valve; Function; Nomenclature Of The Parts; Adjustment - Biasi Riva Plus HE M296.24SR/C Service Manual

9

mOdulatinG Gas valve

9 .1 function

The Modulating gas valve A in Figure 9.1 controls the gas inflow
to the boiler burner.
a
figure 9 .1
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.

9 .2 nomenclature of the parts

- (figure 9 .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
- 24 -
Modulating gas valve
figure 9 .2

9 .3 adjustment

for the pressure values refer to the technical data section
of the user manual and installation instructions .
1 Remove the case panels and the sealed chamber lid (section
2 Open the gas valve inlet pressure test point (6 in Figure 9.2)
3 Remove the gauge and close the pressure test point 6.
4 Open the gas valve outlet pressure test point (7 in Figure 9.2)
figure 9 .3
5 Remove the protection cap B (Figure 9.3) from the mechani-
6 Start the boiler at its maximum power.
7 Rotate the maximum gas pressure adjustment (2 in Figure
8 Turn the boiler off and disconnect one of the two connectors
9 Start the boiler and rotate the minimum gas pressure adjust-
7
8
6
warning: isolate the boiler from the mains electrici-
ty supply before removing any covering or compo-
nent .
"Body panels" page 5).
at the valve input, connect a suitable pressure gauge and
check the gas pressure of the supply network.
and connect the gauge;
cal pressure adjustment components levering with a flat
screwdriver in the slots C.
9.2) until you obtain the required pressure (by rotating clock-
wise the pressure increases).
(3 in Figure 9.2).
ment (1 in Figure 9.2) until you obtain the required pressure
5
4
c
3
2
1
b