Set Appliance State:

Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Mains Isolator Switch (ON/OFF Switch) in ON position
Selector Switch in DHW Summer position
Hot Water Temperature Control set to Maximum
Remove one Wire from Modureg Solenoid (1) and make safe
Attach 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

Observation:

Does main burner ignite with a burner pressure of approximately 2.0 mbar?
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.