In an earlier contribution to this discussion,
The Natural Philosopher wrote:

Roger Mills wrote:

Such a system would be a nightmare to programme though unless your
room usage followed a very regular pattern. Even then, you'd have to
tell each individual stat about things like going on holiday for X
days. Really needs to be programmable from a single point - with the
ability to apply global settings to all stats in one go - but I'm
not sure how to go about that. I don't really want to run a
dedicated PC *just* the operate the heating!

No need to program anything. Just go into a room, switch it ON, forget
timers by and large, and if its too cold on comes the heating.

You just 'wire OR' the motorised valves..(connect em in parallel)

OK - so when you go on holiday for a fortnight in winter, how do you tell it
just to provide frost protection until the day *before* your return, and
*then* revert to the normal cycle in order to ensure that you return to a
warm house?

I can easily do that with my (single heating zone) system, controlled by a
CM67 programmable thermostat.
--
Cheers,
Roger
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