Problem with central heating. micro switch adjust?

[maximan]

Hi.
Seem to have a problem with central heating (heating). Turn on heating and all is ok until I adjust room stat, if it turns off heating and then I turn it up again it will not call for heating on boiler. Valve is opening and if I turn on the hot water the radiators start to heat up, but turn hot water off again and heating goes off. This can last for a few hours and then you can turn heating on again. Plumber changed programmer (honeywell) but problem persists.
2 2port valves (honeywell?)and vaillant boiler.

Thank you for any replies, Max.

 

[picasso]

The 2 port valve that controls your central heating is faulty, the motor isint making the micro switch reliabily so you would be better to change the valve head.

 

[maximan]

Thank you I think I had also almost reached that conclusion.

 

[maximan]

Picasso, do you think that the microswich can be adjusted or is a new head the only answer?

 

[picasso]

New head

 

[maximan]

Fiddled with the actuator for micro switch now all appears ok. probably was making cold but as warmed up was not making full contact?? Many thanks for steering me in right direction.