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:

After boiler completes self-check the boiler should begin to run for DHW demand.
The DHW demand LED should illuminate and display should show the target temperature.
The right hand side of the display should show 3 (fan proving / purge)
for approximately 5 seconds before changing to 4 (ignition).