Servicing And Removal Of The Gas Valve; Setting Gas Pressure - Ariston EuroCombi A/23 MFFI Servicing Instructions

1.4 Servicing and Removal
of the Gas Valve
1
B
A
2
D
C
3
4
B029
Setting gas pressures
Setting the minimum and the maximum power of the boiler
1. Check that the supply pressure to the gas valve is a minimum of 20 mbar
for natural gas.
2. To do this, remove the screw "A".
Fit the pipe of the pressure gauge to the pressure connection of the gas
valve "B".
When you have completed this operation, replace the screw "A" securely
into its housing to seal off the gas.
3. To check the pressure supplied by the gas valve to the burner, remove the
screw "C". Fit the pipe of the pressure gauge to the pressure outlet of the
gas valve "D".
Disconnect the compensation pipe either from the gas valve or from the
sealed chamber.
4. Set the On/Off button to position < I > and the "summer/winter" switch to
the winter position.
To set the maximum power, turn on the hot water tap and allow the hot
water tap to run at a rate of about 8 litres/minute so that the main burner
lights.
Adjust nut "E" on the modureg to set the gas pressure (displayed on the
pressure gauge) corresponding to the maximum power (see table "A" page 11).
5. To set the minimum power, disconnect a supply terminal from the modu-
reg and adjust screw "F".
Turn the screw clockwise to increase the pressure and coun-
ter-clockwise
pressure gauge) corresponding to the minimum power (see table "A" page
11).
6. When you have completed the above operations, turn off the
hot water tap, re-connect the supply terminal to the modureg
on the gas valve and replace the cap on the screw of the
modureg.
Setting the maximum heating circuit power
7. To set
On/Off button to position < I > and the "summer/winter" switch to winter
position.
Turn the knob of the heating thermostat clockwise to maximum;
E
8. Remove the left hand inspection panel of the P.C.B. and fit a small
cross-head screwdriver in to the right hand potentiometer. Turn clockwise
to increase the pressure or counter-clockwise to reduce the pressure.
Adjust the setting to the required heating pressure value (displayed on the
pressure gauge), as indicated in the diagrams shown in page 11.
9. Turn off the boiler by placing the main switch to the "Off" position.
Setting pressure for soft ignition.
Disconnect the detection electrode connection from the P.C.B. (see fig.
1.13).
Start the boiler and during the ignition sequence adjust the centre poten-
tiometer until the gas pressure reads the required gas pressure as per the
table below.
F
Once the gas pressure is set turn off the boiler and reconnect the connec-
tion to the P.C.B.
NB.: It may be necessary to reset the flame failure reset a number of times
during this operation.
to decrease the
the maximum heating
pressure (displayed
circuit power, place
on the
the
11