Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Flow and return valves fully open
CH thermostat set to MAX
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow the boiler to ignite and run in central heating mode.
Is the heating operating satisfactorily?