Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
CH Demand
Refit wires to APS if you have not already done so
Connect the air pressure switch charge kit to +ve connection on the air pressure switch, disconnect the -ve connection and ensure there is no pressure
Ensure that the Boiler Thermostat is set to MAX
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Approximately 2 seconds after the fan starts to run increase
the pressure via the syringe to the point that continuity
was measured on the previous test.
With the APS manually made can sparking now
be observed between the ignition electrodes?
Note:
If sparking is not noticed it is permissible
to increase the pressure by up to 50%