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 and burner to ignite.
To check the minimum heating gas pressure, rotate the CH temperature control until pressure drops to minimum (should be as per table).
Note:
When gauge is removed pressure test point should be tightened and checked for gas tightness.