Set Appliance State:

Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Attach pressure gauge to burner pressure test point
DHW temperature selector to 0 position
CH temperature selector to 0 position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Reset lockout as necessary.
Allow appliance to self check and return to standby mode.
DHW temperature selector to maximum position.
Allow fan to run and burner to ignite.
Does the gauge show a ramp up in pressure to approximately 30.4 mb (Propane LPG G31)?
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.