Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
DHW temperature selector to MAX
Disconnect 1 wire from the gas valve modureg and make safe
Attach pressure gauge to burner pressure test point
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow fan to run and ignition sequence to commence.
Does the burner ignite and sparking cease at minimum pressure of approximately 1.8 mb (N.G)?
(For L.P.G refer to ADAPT / data badge, burner pressure test point may also be different.)
 
Isolate Mains Power to appliance as per TOP's P4
Reconnect the modureg wire.
Mains Power On.
 
Allow fan to run and ignition sequence to commence.
After a short time the pressure should increase to its maximum of approximately 10.5 mb (N.G).
Note: When pressure gauge is removed pressure test point should be tightened & checked for gas soundness.