Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect leads from APS making a note of their positions
Remove APS from boiler
Connect the air pressure switch charge test kit to P1 (+ve) on the APS
Note the operating pressure which is indicated on APS
Remove APS from boiler
Connect the air pressure switch charge test kit to P1 (+ve) on the APS
Note the operating pressure which is indicated on APS
Measurement:
Increase the pressure via the syringe to that indicated on the APS.
Measure the resistance between terminals 1 and 3.
Expect continuity/zero resistance.
100 Pascals = 1mbar / 50 Pascals = 0.5mb.
Measure the resistance between terminals 1 and 3.
Expect continuity/zero resistance.
100 Pascals = 1mbar / 50 Pascals = 0.5mb.
Isolate as per TOPs P4
and refit as necessary