Set Appliance State:

Mains Power Off
CH Demand
Selector Switch to Hot Water and Heating
CH thermostat set to MAX
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow the burner to ignite and the boiler to run for central heating.
Monitor the operation of the appliance and system as well as the system pressure.
Is the heating operating correctly and does the system pressure remain stable?