Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Turn off the mains water supply
Turn Hot Water Tap ON (to relieve pressure in supply)
Boiler Switch in ON position
Central Heating Switch in Constant position
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Does central heating flow pipe get hot approximately 2 minutes after burner has lit?