Set Appliance State:

Mains Power Off
CH Demand
On/Off Switch in ON position
Mode selector switch to Constant
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Operate the Central Heating until the boiler reaches its full operating temperature (i.e. burner shuts down) and then check that the fan continues to run.
NOTE:
It may be necessary to turn off some radiators for this test.
This will assist the boiler to reach operating temperature and speed up the test.