Set Appliance State:

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

Observation:

Turn the DHW temperature selector to minimum then
back to approx. 60°C to disable appliance preheat.
Turn hot water tap on.
Does the boiler recognise a DHW demand?
(Right hand LED illuminates)