Motorised valve problem

[gazsheff]

Hi

Intermittently my heating does not heat rads have found that it seems to be the flowshare 2 sticking so I changed motor but it still happens. If I turn thermostat on tank up so it clicks on lever is driven up to water setting but if I then turn tank stat down after a period of time there is a gurgling noise pump stops and the lever stays put i.e does not drop down to heating even though the room stat which has an indicator is calling for heat. If I then manually push the lever down pump comes on and heating returns. What should drive the lever back .Any help appreciated

 

[gas4you]

Check the spindle on the valve body is not sticking.

 

[gazsheff]

Thanks for replying Dave will do best to check this understand top unit comes off. If this is the case does it mean a new valve?. New programmer fitted not long ago by a gas company was begining to wonder if wired right. If I use valve isolator switch provided lever rises all way up to hw if I then put tank stat on and room stat on and switch isolator back on valve goes to mid if i then switch off tank stat, lever drops to ch I think this is correct Then if I switch tank stat on lever rises to mid ok so far problem seems to be if tank stat then is switched off even though room stat is calling for heat lever does not move back down and boiler and pump go off. Hence from morning switch on everything is ok but then at some point (I think when tank has cooled) you notice heating has stopped and I have to push lever manually