Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Attach U-gauge to gas valve outlet pressure test point
Set boiler to minimum output by turning the service mode to MIN
(Remove cover at front of appliance then panel slides down)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow boiler to commence its ignition sequence and ignite.
Is the MIN burner pressure 0.7mbar?
Set boiler to MAX output setting via the gas valve mode switch.
Is the MAX burner pressure 14.1mbar?
Notes:
1. When U-gauge is removed pressure test point should be tightened & checked for gas tightness.
2. If both pressures are ok, set the boiler back to normal mode via the gas valve mode switch