Set Square wrote:
In an earlier contribution to this discussion,
wrote:

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?

ta!

steve

These things can occasionally get confused, and need a master reset!

The first thing to try is to remove *all* power to the thing. This
means turning off the isolator which provides power to the whole
heating/hot water system - *not* just turning off at the programmer.

With all power removed, does it return to the home (hot water only)
position? If it *does*, try using it as is for a few days - this may
have fixed it.

If it *doesn't* there is either a problem with the spring return
mechanism in the actuator, or the mechanical (wet) part of the valve
is stuck. Remove the actuator from the valve (2 screws, no need to
drain down). Does the actuator *then* return to the home position? If
so, the valve is probably stuck. You should be able to turn the
spindle with your fingers or - at any rate - with only *light*
pressure, using a pair of pliers.

If the valve is stuck, you may be able to free it by rotating the
spindle back and forth. If not, it's a new valve - which *does*
require a partial drain down - unless you have strategically placed
isolator valves.

HTH.

i havenet tryed turning off the power yet...will try tonight...but i have
taken the actuator off and the spindle is free...so if tonight with the
power off it dont move to hw only...then the spring return is faulty? is it
possible to repair?

steve