Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Unclip diverter valve and place in a position where the diverter spindle can be easily observed
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Tap reset button to skip self check.
Allow boiler to start to run for DHW demand.
Is the diverter spindle in the fully extended position?
(As shown in picture)