Set Appliance State:

Mains Power Off
Gas Off
Turn Hot Water Tap On
Boiler On/Off Switch ON
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Honeywell:
Resistance should be felt on Manual Operation lever as it is pushed across.
Sunvic:
Remove two screws holding actuator head to base and remove head.
Flat of 'D' on actuator head should lay inline with the line of the flex.