Set Appliance State:
Mains Power Off
Set Multimeter to DC Volts 
Locate primary system filling loop
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
1. Measure for DC voltage across pin14 (red lead) of connector X2 and a suitable earth connection, make a note of the voltage measured.
2. Increase the primary system pressure slightly, measure the DC voltage as above, has the voltage increased after an increase in system pressure?
Note:
Pins are numbered on the connector.
2. Increase the primary system pressure slightly, measure the DC voltage as above, has the voltage increased after an increase in system pressure?
Note:
Pins are numbered on the connector.
Isolate as per TOPs P4
and refit as necessary