HW but no CH

[gtmpaul]

Hi, we have a gloworm conventional boiler.
When you turn on the HW all seems ok, if you turn on the CH the light comes on on the programmer but the boiler fails to start. the system has two motorised valves, I assume one for HW and one for CH,with the boiler running on HW if I manually open the other valve we have CH. Could this be a faulty motorised valve? can these be tested?

 

[kevplumb]

if its not moving its duff you can (in most cases ) replace the head or the motor