Set Appliance State:

Mains Power Off
Boiler mains switch ON
CH temperature to MAX
CH demand
Integral timer set to DHW ON and CH ON
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Does the boiler react to CH demand?
(A CH demand is recognised when a small radiator symbol appears in the display)