"Roger Mills" wrote in message
...

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.

I zoned my house when I installed CH 25 years ago.
Five zones five programmable stats (well they were timers and stats 25 years
ago but I replaced them with more advanced digital timer stats a few years
ago.
Works very well and there is no change to the settings between winter and
summer.
I just wish the valves were more reliable as I have had to replace all of
them now.