Davey wrote:
On Sun, 29 May 2011 14:05:44 +0100

Interesting, and I have found the reference you quote. So that's not
it, then.
I'll work my way around the house, checking all the valves in the same
way. I wonder if there is a known problem with the sensor heads, or if
they are not very good even when new? All of mine behave the same way,
ie not very well at all.
Thanks.

Check to see if the ones you have can be fitted to either flow or return
and that they are on the flow side of the rads if not.

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