Clunking actuator

[gillsy11]

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

 

[45yearsagasman]

When you say actuator,do you mean diverter valve and if so what make?

 

[gillsy11]

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.

 

[shorky]

you may find it will be the paddle in the valve itself, had this on honeywells before, speed of the water moving slams the paddle shut instead of the valve moving at a slow speed, this normally makes a noise when you turn heating/hotwater on and off, all you can do is replace the complete/ 3-port or zone valve whichever it is.

 

[gillsy11]

Is this an easy to do job? and is it expensive??