Central heating is fine but no hot water. Diaphragm is ok and microswitch makes clicky noise and works if pushed manually. Pin does not seem to move when hot water is drawn.
Any ideas ?

Mark Hanney, December 2007

just replace the diverter valve

lee, January 2008

Possibly the pressure relief valve is jammed open with a fragment of perished diaphragm, and may be cleared with a bit of fiddling?. Perhaps more likely than a broken spring?. Post your findings?

c, January 2008

One last possibility, with the diaphragm out you should see a white nylon insert behind it. There is a spring loaded pressure relief bit in the middle. If you poke the middle with a small screwdriver you should be able to push it down and it should spring back. If it doesn't work there will be no pressure difference across the diaphragm when you draw hot water. It looks as if it comes out with a two dog removal tool, such as the circlip pliers you see in pound shops.

c, January 2008

Sorry, didn't read your post properly. I dont know why the pin does not move at all when you draw hot water if the diaphragm is indeed OK.

c, December 2007

Google 'Vokera diaphragm', or search this site; for example:

http://fixed4free.com/answers.php?id=89783

c, December 2007