Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect leads from the air pressure switch noting the connections
Remove the air pressure switch from the boiler (if required)
Remove the air pressure switch from the boiler (if required)
Measurement:
Note the operating pressure indicated on the pressure switch. Connect the air pressure switch charge test kit to
P1 (+ve connection) on the air pressure switch.
Increase the pressure via the syringe to that indicated on the pressure switch.
Continuity should then be measured between common and normally open terminals on the air pressure switch.
Note:
If continuity is not obtained, it is permissible to increase the pressure by 50%.
100 Pascals = 1mbar / 50 Pascals = 0.5mbar
P1 (+ve connection) on the air pressure switch.
Increase the pressure via the syringe to that indicated on the pressure switch.
Continuity should then be measured between common and normally open terminals on the air pressure switch.
Note:
If continuity is not obtained, it is permissible to increase the pressure by 50%.
100 Pascals = 1mbar / 50 Pascals = 0.5mbar
Isolate as per TOPs P4
and refit as necessary