Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Attach pressure gauge to gas valve test point
Boiler Switch in ON position
Central Heating switch in constant position
Central Heating potentiometer set to MAX
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow burner to ignite, and boiler to run.
Boiler should run on low rate for approximately two minutes before increasing to maximum rate.
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.