Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect the 5-pin electrical plug connecting the air pressure switch and fan Withdraw the fan assembly by pulling forwards from the top edge
Disconnect leads from the air pressure switch noting the connections
Disconnect leads from the air pressure switch noting the connections
Measurement:
Note the operating pressure indicated on the pressure switch. Connect the air pressure switch charge test kit to the +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.
Notes:
1. APS is shown removed from the burner door / flue hood assembly but test can be carried out with it still fitted.
2. If continuity is not obtained, it is permissible to increase the pressure by 50%.
3. 100 Pascals = 1mbar / 50 Pascals = 0.5mbar.
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.
Notes:
1. APS is shown removed from the burner door / flue hood assembly but test can be carried out with it still fitted.
2. If continuity is not obtained, it is permissible to increase the pressure by 50%.
3. 100 Pascals = 1mbar / 50 Pascals = 0.5mbar.
Isolate as per TOPs P4
and refit as necessary