Need to run hot water to start central heating

[relief]

Potterton suprima boiler, tank in airing cupboard, 3 port valve with a potterton myson 322 actuator.
Ok to get the heating on you need to run the hot water tap. else it wont start, on the bottom of the actuator is a switch auto or mid... when switched on mid sometimes the heating comes on without the need to run hot water but sometimes doesnt.
Auto and nothing, is the switch on these suppose to spring back to the auto position like the synchron motor older style.. ie: to keep in the mid position you need to clip it under the retaining clip.
Do you think that could be the problem or what other poss causes, let me know if you need more info.
Thanks

 

[GasMan1965]

Sounds like the syncron motor in zone valve!!

take the head off and check the spindle moves freely,, also while the head is off try the controls to see if it responds

 

[MANDATE]

While you have the head off make sure the spindle is free to turn.
If you find the head does go acroos to the CH only positon and the boiler does not light then micro switch faulty.
The side lever is for retaining the valve in mid position while filling.The micro switch is mounted just past mid point, hence using the lever to assist a faulty motor sometimes works.