On Tue, 20 Mar 2018 09:30:50 +0000, Chris B wrote:

On 19/03/2018 10:56, Tricky Dicky wrote:
Tim the valve itself is crud free and the pin pushes and releases
easily it is the head itself that is the problem.

Chris the room temp was set at 21C, Hive itself seems to do a good job
of not letting the temp rise no more than +/- 1C. On its maximum
setting the valve should not be closing until the temp rises at least
6-8C above that. The fact that it was still closed at 2C below the room
temp setting means it has an inaccuracy of 10C that's some range? Looks
like I will need a better valve. Any suggestions?

Richard


No, If on its "fully on" setting its closing the valve before the room
gets above 21C, then bearing in mind what you have said about the
freedom to move of the "wet" part it looks like you have a faulty head.

Your web link was to a screw-fix valve I think, if so take just the head
back, they may let you just swap the head and see if another one of the
same type works better.

One final thought, there aren't any washers or spacers between the valve
and the head that have been omitted on assembly? The behaviour you
describe implies that the actuator is "too close" to the valve.

With some designs of TRV, it's possible that the head may have slipped a
few notches from its calibrated position. ISTR this happening with one TRV
due to "Brute Forcing" an adjustment. If it's a new valve, it might
simply be an incorrectly assembled unit that slipped past QA at the
factory so it would certainly be worth returning it for a warranty
replacement or if it's a very recent purchase, your supplier should be
prepared to offer an alternative make/model with price difference
adjustment if the returned valve looks undamaged enough to be RMAd back
to his supplier.

--
Johnny B Good