Radiators pumping out heat when boiler is off?

[Kewat66]

Hi All,
i have a Worcester boiler connected to 2 small cylinders. I am turning the boiler off but the rads are still red hot hours after. The programmer is only used for the heating so the hot water appears to be controlled by the stats on the cylinders. I am thinking that may be the motorised valves on the circuit aren't closing properly and are keeping the pump going?any thoughts or suggestions?
thanks
kewat66

 

[jtsplumbing]

Is this a fully pumped system ??

 

[Kewat66]

Yes

 

[jtsplumbing]

Need to check if cylinder connection is last back to boiler,