Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Set selector switch to ch/dhw
Dhw temperature control to max
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

Observation:

Allow the boiler to execute its ignition sequence and the burner to ignite.
Does the burner pressure operate between MAX and MIN pressures as the dhw flow rate is altered via a dhw tap?
Note:
When gauge is removed pressure test point should be tightened and checked for gas tightness.