Modulating Gas Valve; Function; Nomenclature Of The Parts; Adjustment - Biasi Parva HE M96.24SM/P Service Manual

11

Modulating gas valve

11.1

Function

The Modulating gas valve A in Fig. 53 controls the gas
inflow to the boiler burner.
A
Fig. 53
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. 54)
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
8
7
6
5
Fig. 54
11.3

Adjustment

Warning: isolate the boiler from the mains
electricity supply
covering or component.
1 Remove the front panel of the case.
2 Open the gas valve inlet pressure test point (6 in
Fig. 54) 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 Fig. 54) and connect the gauge;
Remove the protection cap B (Fig. 55) from the
5
mechanical pressure adjustment components
levering with a flat screwdriver in the slots C.
1
2
3
4
before removing any
25