Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
CH Demand
Attach pressure gauge to the inlet pressure test point
Ensure No other gas appliances are in use
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset boiler if required.
Allow the ignition sequence to commence.
A drop in the standing pressure should be seen as the gas valve opens.
Note:
1. No other gas appliances must be in use during the test. The appliance will have 5 ignition attempts approximately 5 seconds apart and gas will only pass for approximately 3 seconds on each ignition attempt.
2. When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.