Set Appliance State:

Mains Power Off
CH Demand
Boiler On/Off Switch ON
CH Mode Switch in its 24hrs position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Honeywell:
No or little resistance should be felt when the manual operation lever on the Diverter Valve is moved to its open position.
Sunvic:
Remove actuator head, flat of 'D' should lie across the line of the flex.