Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
DHW Demand
Undo Burner Pressure test point
Attach pressure gauge to the burner pressure test point
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Allow ignition sequence to commence.
Does burner pressure increase to approx 2.5mbar.
If Burner pressure is low then it can be set.
Instructions for setting up Burner Pressures
When gauge is removed pressure test point should be tightened and checked for gas tightness.