Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
CH temperature control to max
Selector switch set to ch/dhw
Connect a U-gauge to the Burner Gas Pressure Test Point
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow the boiler to execute its ignition sequence, as sparking commences.
Does the burner pressure increase to MAX as per the table?
Notes:
1. Burner pressure will depend on boiler temperature.
2. When gauge is removed pressure test point should be tightened and checked for gas tightness.