Just a quick thanks to all who replied and FWIW my observations on
subzoning.

Also in respect to savings (on my system) I can confirm it saved its
cost in just over 2 years.

In message , Christian
McArdle writes
So once the room with the thermostat is up to temp, the rest of the
house 'loses' it's heating until the thermostat closes again ?

Yes. Either put it in the coldest room so the rest of the house is already
up to temperature before it closes off, or put it in the room you are likely
to be using (i.e. lounge) so you don't care that the rest may not be as
accurately controlled.

Much better still, use subzoning and have different programmable thermostats
for each zone. I have zones for upstairs (bedrooms), downstairs
(receptions), kitchen and (soon) conservatory. This way each can have a
different temperature profile over time to reflect usage patterns and each
follow more accurately the desired temperature. The thermostats are placed
in the most used (or only) room in each zone.

A word of caution here, it really is "horses for courses". I had a
well insulated double glazed 70's semi and plumbed downstairs and
upstairs zones on separate thermostats/timers.
The system worked OK but as I left most doors open, the upstairs
bedroom heated up during the day and only in the extremes of winter
would it call for heat!!
So (in my particular case) the extra expense/time fitting was not
justified.
I agree with the subzoning principle for your layout. but I think cost
benefits of plumbing four zones might well be marginal particularly if
you had to pay for all the work!


Christian.



Thanks
--
Peter H