Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
ON/OFF Switch ON
Summer/Winter button set to Winter
CH Temperature selector to maximum
DHW Temperature selector to maximum
Remove the diverter valve head
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Diverter valve spindle should be fully retracted.
Replace diverter valve head after test.