Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Ensure that the Boiler Thermostat is set to MAX
Connect a U-gauge to the Gas Valve outlet pressure test point
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow the fan to run and the pilot to ignite.
Does the burner cross light from the pilot and operate at the correct burner pressure as stated in the manufacturer’s instructions.
Note:
When U-gauge is removed pressure test point should be tightened & checked for gas tightness.