"Mike Tomlinson" wrote in message ...

[Danfoss TRVs]
but they are easily unstuck without the need to drain
down and with no more than a few cc of water spilt.

Any chance of more info?

1. Ensure that the system pump is not running.

2. Remove the TRV sensor head.

3. Unscrew & remove the 'gland seal' - this is the central hex headed
brass assembly which holds the actuator pin. The innards of the
valve are now exposed and a slight seepage of water is usual at
this point.

4. Using something small and round, such as a small electrical
screwdriver, feel inside for the recess that the actuator pin
engages with; this is one end of a rod with the valve cone on its
other end. _Gently_ attempt to push this rod from side to side with
a circular or waggling motion, increasing the force applied until
you start to feel the valve un-stick. The internal spring does the
rest and the rod will pop outwards by a few mm, accompanied by a
little gush of water (have old towels ready).

5. Quickly replace the gland seal and tighten.

6. Press on the actuator pin and ensure that it returns under spring
pressure - you can easily distinguish between stuck and unstuck
valves by the feel of their pins.

7. Replace the head.

HTH
--
Andy