Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Mode Selector Switch to DHW position
Connect 'U' gauge to burner pressure test point
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Is burner pressure 11.2 mbar?
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.