Set Appliance State:

Mains Power Off
Gas On; Pilot On
Turn Hot Water Tap On
Selector Switch Summer position.
Gas Control Knob in Main Burner position
Connect U-gauge to pressure test point
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

With the Main Burner alight, check the burner pressure rises to the set pressure.
(Maximum pressure is 15.8 mbar.)
Note:
When U-gauge is removed pressure test point should be tightened & checked for gas soundness.