Modulating Gas Valve; Function; Nomenclature Of The Parts; Adjustment - Biasi M96A.24SM/B Service Manual

11

Modulating gas valve

11.1

Function

The Modulating gas valve A in Fig. 1 controls the gas
inflow to the boiler burner.
A
Fig. 1
By means of an electric command given to the on---off
operators the passage of the gas through the Modula-
ting gas valve can be opened or closed.
By means of an electric command given to the modula-
tion operator the pressure can be varied and therefore
the gas flow rate to the burner (modulation). The mo-
dulation operator has mechanical components which
allow the adjustment of the minimum and maximum
pressure exiting the valve.
11.2 Nomenclature of the parts (Fig. 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
7
8
6 4
Fig. 2
11.3

Adjustment

For the pressure values refer to the Technical data
section of the User manual and Installation instruc-
tions
Warning: isolate the boiler from the mains
electricity supply
covering or component.
1 Remove the case panels and the sealed chamber
lid (see section 2).
2 Open the gas valve inlet pressure test point (6 in
Fig. 2) at the valve input, connect a suitable pres-
sure 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 Fig. 2) and connect the gauge;
C
Fig. 3
3
2
1
5
before removing any
B
27