Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Is the diverter valve in the DHW position ?
Note.
It may take approximately 40 seconds for the boiler to recognise
a demand, this will depend upon the boiler status.
(Status code guidance CLICK HERE)