Set Appliance State:

Mains Power Off
CH Demand
Ensure no DHW demand and that radiators are not up to temperature
CH temperature control to MAX
Selector switch in CH & HW mode
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

After approx 5-10 seconds of the power being turned on does the fan begin to run?