On Tue, 2 Apr 2019 15:25:07 +0100, "www.GymRatZ.co.uk"
wrote:

On 02/04/2019 08:33, T i m wrote:
snip
This was all the rotation I could get (without forcing anything
anyway).

http://tinypic.com/r/244v3fp/9

Running the system with the MV head off and turning the valve manually
wasn't that revealing as the system was already hot and once hot it
didn't cool that quickly.

Did you see the following page?
http://www.freeheatingadvice.com/art...-valve-faults/

I did now, thanks, very interesting / informative.

I recently had to replace 2 Honywell 3-way valves in the shop which had
been in service for around 17 years! Replacement valves were the same
length and wiring but the threads were different so had to cut olives
off. Partially cutting through the olive so as not to damage pipe then
putting a flat-blare screwdriver in the saw cut and rotating fractured
the remaining bit of olive without risk to pipe.

Understood.

I'd have thought the spindle should rotate significantly further than
the few degrees in your picture.

Well, from the picture shown on your link (and what Mr Rumm says
elsewhere):

http://www.freeheatingadvice.com/wp-...valve_ball.jpg

.. it looks like the two end 'stops' are when the ball contacts
(blocks) each port in turn. With the pump running and turning the
valve spindle by hand, you can feel / hear the ball being pushed
against the port with quite a bang (suggesting there is a good
pressure build up in the valve till the water gets moving through the
opposite port, whereas moving it to the opposite end doesn't seem to
have the same effect. That might suggest the ball isn't seating quite
so well in that port or there isn't quite so much resistance to the
build up of pressure in that direction etc?

Might be worth changing the valve anyway if it's been in used for 10
years or more,

I'll ask her if she knows how long it's been in there (she remembers
all sorts of obscure stuff [1]) and it does look like it's not the
original fitting.

and I'd suggest changing nuts/olives anyway to ensure
everything mates up nicely.

Understood.

The old nuts on mine screwed on 2 or 3
rotations onto the valve body before jamming which initially looked like
they matched.

I think I'd check that one port (AB) seated fully first and if so, re
use them with a bit of paste?

Cheers, T i m

[1] At 84 she can still clearly remember her days working on
inspection and repair during her days at Thorn. ;-)