Set Appliance State:

Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
DHW temperature control set to maximum
Attach pressure gauge to burner pressure test point
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Appliance On/Off control set to ON position.
Reset lockout as necessary.
Allow the fan to run and ignition sequence to commence.
With a DHW demand is the burner pressure approximately as per the table?
Note:
When pressure gauge is removed pressure test point should be tightened and checked for gas soundness.