Set Appliance State:

Mains Power Off
CH Demand
Ensure all heating controls are calling and thermal store is up to temperature
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset lockout if necessary.
Allow boiler to fire under CH demand.
Does the system heat satisfactorily and the system pressure remain at the correct level?
System pressure should be approximately 1 bar.