Set Appliance State:

CH Demand
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Does the boiler respond to a CH demand (CH symbol flashing)?
Note.
It may take approximately 60 seconds for the boiler to recognise a CH demand after a DHW demand, this will depend upon the boiler status.
(Status code guidance CLICK HERE)