Set Appliance State:

Mains Power Off
Gas On; Pilot On
CH Demand
Selector switch in CH CONTINUOUS position
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow fan to run and burner to ignite.
Does the CH system start to heat up correctly?
Note: If power has been switched off or CH demand has been interrupted, there will be a delay of between 1 and 3 minutes before the boiler starts.