Gas Valve; Function; Description Of The Parts; Adjustment - Biasi Activ A 25C Service Manual

11

Gas valve

11.1

Function

The Gas valve A in Fig. 11.1 controls the gas inflow to
the boiler burner.
A
Fig. 11.1
By means of an electric command given to the on---off
operators the passage of the gas through the Gas valve
can be opened or closed.
11.2 Description of the parts (Fig. 11.2)
5
Fig. 11.2
1 Maximum gas pressure adjustment
2 Minimum gas pressure adjustment
3 On---off operators
4 On---off operators electric connector
5
11.3
Check the supply pressure before making any ad-
justment to the gas valve.
1
2
3
4
5
6
Fig. 11.3
7
8
9
1 10
2
Gas valve adjustment
11
3
4
Fig. 11.4
12
13
Gas valve inlet pressure test point

Adjustment

Warning: isolate the boiler from the mains
electricity supply
covering or component.
Close the gas inlet valve.
Remove the front panel of the case and lower the
control panel (see sections 2.2 and 2.3).
Loosen the internal screw on the Inlet Pressure
Test Point 5 (Fig. 11.2) of the Gas valve and con-
nect a pressure gauge using a suitable hose.
Open the gas inlet valve.
Turn on the electricity supply to the boiler, switch-
ing on the fused spur isolation switch.
Set the boiler in c.h. / d.h.w. function as illustrated
in Fig. 11.3
Open at least one hot water tap fully.
Read the inlet pressure value and ensure that it is
within the limits given in the table Gas supply
pressures, of the user/installation manual
If it does not comply with the required pressure
check the gas supply line and governor for faults
and/or correct adjustment.
Switch off the boiler close the gas inlet valve and
close the water tap.
Disconnect the pressure gauge and close the
Inlet Pressure Test Point 5 (Fig. 11.2).
Fit the probe of the flue analyser in the flue ex-
haust sampling point located on the exhaust
pipes of the boiler (Fig. 11.4).
air intake
sampling point
Turn on the boiler, switching on the fused spur
isolation switch.
Open the gas inlet valve.
before removing any
C.h. / d.h.w.
function
flue exhaust
sampling point
27