Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Remove diverter valve actuator, place in a safe position where the spindle can be observed
Use insulation Mat as required
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Turn a hot water tap ON.
After 30 seconds:
Isolate Mains Power to appliance as per TOP's P4

With the aid of a screwdriver confirm the actuator spindle
is in the recessed position (DHW position)?