Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Gas On; Pilot On
Boiler On/Off Switch ON
CH Switch OFF
DHW Switch in INSTANT position
Connect a U-gauge to the burner pressure test point
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

With the DHW tap fully open does the burner ignite and operate at its maximum gas pressure of approximately 10.6mb?
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.