"fred" wrote in message ...
In article , G&M
writes

"Set Square" wrote in message
...
I am considering overhauling and zoning my central heating later this
year,
and would like separate control of each rad. I'm looking for motorised
valves which are as small as possible and which will fit on 15mm pipes.
The
only ones I can find are 22mm. [Yes, I know I can use reducers - but
the
whole thing is still too big].

Does anyone know whether smaller ones are available and, if so, where
from?

I have seen ones in Scandanavia that appear to use the valve from a TRV
together with what I assume is an electromagnet. This is 15mm and very
small, though the peak flow is quite low I imagine.

But not sure where you get them in the UK.

The ones I've heard of use the mechanics of a TRV and a heater to activate
the TRV capsule. Have seen them recently in individual hospital rooms to
have timed control but they seem to be v expensive by virtue of low
demand. They have been mentioned in this group, try a google groups.
Andy Gabriel I think has mentioned making a low cost version by adding a
heater to a regular TRV, again google.

Ahem!

http://groups.google.com/groups?selm...pc16.rdg.ac.uk