Set Appliance State:

Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Operating Switch in Water position
Connect U gauge to burner pressure test point
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure gas pressure at the Burner Pressure Test Point on the Main Gas Valve.
Note:
When U-gauge is removed pressure test point should be tightened & checked for gas soundness.