Set Appliance State:

Mains Power Off
Function selector in standby position
All CH controls calling
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

While observing the diverter valve actuator switch the function selector from stand by position to heating position.
Actuator spindle should extend to the heating position.
Switch the function selector back to stand by position.
Actuator should retract to the DHW position.
Note:
It is important that the actuator has the spindle side uppermost during the test.