In message ,
writes
hi all, i have a danfoss hsv3 valve on my central heating that is
malfunctining... it is fine when ch is on or hw and ch is on but not when hw
only should be on...it stays in mid position. other than draining down and
fitting a new one or changing the powerhead...are they repairable? i have
some skill with a soldering iron so would be happy to give it a go! anyone
help me out with some tips?

There was a thread about just the very same point a week ago, you can
google for it
--
geoff