Can someone confirm my suspicions.....
New house, well 5 years old, and CH has stopped working though hot water is ok.
When turn CH on I get a buzzing from the airing cupboard. Noise is coming from a white box ie :
myson power extra mpe322 ipx2
6w 36mA motor load max ambient 52 'c water temp 5' to 95' 2 ports ie < ch dhw >porta portb
This has a manual override lever which is a bit stiff but can be moved up and then to one side to sit in a slot. If I do this the radiators then get hot.
I now understand that this box is an actuator and sits on a valve. So I figure this actuator is the problem unless it is the valve that is sticky. So removed actuator from valve turned CH and it starts its repeated buzzing again. Also the valve does not appear sticky. So I think it is the actuator except I am confused in that when I move the manual override lever - remember actuator is not connected - then the heating appears to start ie I hear the pump start up. The lever did not appear to turn the whole in the centre of the acutator. I thought this should happen ie that the valve would need to be turned. The valve appears to stay in an 11'0'clock position which I think means supply both HW and CH.
I have had a look for the actuator and seen the myson mpe322 at :
Am I right in thinking its the actuator thats at fault and can anyone recommend where to obtain a replacement? Thanks.