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.
Allow self-check to complete and burner to ignite and establish.
After 40 seconds;
Isolate Mains Power to appliance as per TOP's P4

With the aid of a screw driver confirm the
actuator spindle is in the raised position
and cannot be pushed down (DHW position).