Set Appliance State:

Gas Off
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Attach U gauge to inlet pressure test point
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset lockout as necessary.
Ensure no other gas appliances are in use.
Allow the ignition sequence to commence.
Monitor the inlet pressure during the ignition cycle, a drop in the standing pressure should be seen as the gas valve opens.
Notes:
1. The inlet pressure should remain above 18mb through the ignition sequence.
2. When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.