It is a siemens demountable actuator DVA3 230v 50 hz 3 amp midposition cmv 322. The noise only starts when the heating is warm. If we isolate the supply from the main switch it stops, we put the main switch back on, no noise, click the heating on how ever and it starts again.
When the central heating is turned on there is a loud clunking sound coming from the actuator. The radiators are still hot and the water is also fine, was hoping someone could shed some light on the problem and is it an easy problem to resolve.
Thanks