Checks; Removal Of The Pressure Switch - Savio GAIA 424 S Service Manual

17 Water pressure switch and
pump relay
17.1 Function
The boiler is equipped with two water pressure
switches which are connected to the main (c.h.) water
circuit.
They have two different operating points and, by
switching an electric circuit, they indicate the water
pressure by means of the display circuit (fig. 77).
The lower limit pressure switch interrupts the power to
the pump via the pump relay, in the event that the sys-
tem pressure drops below 0.5 bar.
High limit
water pressure
switch
Low limit
water pressure
switch
Pump
relè
fig. 77
The high and low pressure switches can be identified
by the color of the pastic plug situated on the end of
each switch.
The table below gives further details.
Pressure switching point (bar)
0.5
2
17.2

Checks

Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1 Switch off the boiler. Remove the front panel of the
case, lower the control panel and empty the main
circuit.
If you need to verify the operating point of the
switches, connect a suitable water pressure
gauge to a test point of the circuit near the boiler;
Display circuit
Pump
Colour
Black
Red
2 disconnect the connectors to the pressure
switches and measure the electrical resistance
between the connections (fig. 78).
When the circuit is empty, the contact between
the connection COM and the connection NC
must be closed; the contact between COM and
NO must be open.
O
fig. 78
3 Gradually fill the circuit. The lower limit pressure
switch (brown plug) must switch at a pressure of
about 0.5 bar.
Verify that the contact between COM and NC is
open and between COM and NO is closed.
4 To check the high limit pressure switch (red plug)
further increase the pressure of the circuit. It must
switch at a pressure of about 2 bar. Verify the con-
tacts as explained above.
After this test, remember to decrease the water
pressure to an adequate value.
17.3

Removal of the pressure switch

1 Empty the main circuit of the boiler;
2 remove the front panel of the body, the right side
panel and lower the control panel;
3 disconnect the wirings from the pressure switch
and unscrew it.
4 Reassemble the switch carrying out the removal
operations in the reverse order.
Reassembling the pressure switch, refer to the
diagram of the section 3.1 to connect correctly
the wirings.
17.4 Removal of the pump relay
The pump relay is located under the display circuit. To
remove it:
1 gain acces to the electric parts of the control
panel (see sect.2.3):
2 remove the display circuit (see sect.10.3)
3 disconnect the wirings and remove the relay.
NO
COM NC
33