Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Attach a U-gauge to the gas valve burner pressure test point
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Allow boiler to heat DHW to approximately 55 degrees C, reduce flow rate at tap to approximately 5 l/min.
Does burner pressure reduce to maintain a DHW temperature of approximately 55 degrees C?
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.