I went down to Screwfix and picked up a ZA5 valve actuator for £42,99. Fitted it in 10 minutes when I got home and all is well.
Thanks to all of the contributors to this thread.
CVB
I took the actuator apart and found three things that did not look quite right - a small piece of grey plastic broken off the stop post
a small piece of black plastic broken off the top of the post that holds the quadrant and delivers the movement to the valve spindle
a couple of teeth...
Yes, I have a multimeter and have used it for connectivity, voltage measurements, etc. plus I have a neighbour who could help out if it gets complicated.
CVB
I did the first check as suggested and the ch valve tried to open but clicked closed immediately it reached the fully open position. Neither the pump not the boiler came on. Note that I have an oil-fired boiler that has its own temperature controller built into it so that may have prevented it...
See new picture below
There is a white wire (A) but it is not connected but left, as you see, taped up. The other white 'cable' you see is not a cable because it has no conductor in it - it's like a flexible plastic rod (to make up six 'conductors' in the black sheath for better packing of...
Thanks - found the catch on the side. The way the valve is situated, I could not see the release catch. I removed the actuator and found that the pipe part of the valve seemed to be in good order with little effort needed to rotate it through about 60 degrees (guess)
I have two motorised...
When the heating came on this after (timer - 2 periods morning and evening) there was a loud banging noise transmitted through the central heating pipes every 20 seconds or so. When I went to the airing cupboard, I found the noise was coming from the above valve. The lever on the side moved from...
Well, it's been running, without missing a beat, for over a month so thanks to all the contributors for saving me from wasting yet more money with so-called experts.
CVB
A quick update - the condenser arrived last Friday afternoon and I fitted it as soon as it arrived - quite an easy operation.
It has been running now for two days and has not missed a beat so I'm keeping my fingers crossed that I've solved the problem with your help. If it all goes t*ts up...
I spoke today to a nice guy at Riello called Graham who works in their technical department. He came to the same conclusion as you, Burnerman, and suggested I replace the capacitor. I was given the part number and ordered one from Vitalise Trading on Ebay for £10. I'll let you know the outcome...