In message l.net, at
12:49:27 on Thu, 8 Oct 2020, Dave Liquorice
remarked:
On Thu, 8 Oct 2020 11:49:17 +0100, Roland Perry wrote:

Currently I have a boiler with a controller that simply turns it on (for
CH) during pre-programmed hours. Rads have thermostatic valves.

So presumably the boiler short cycles when the timer says on but the
rad valves have all shut, pushing up your energy bill...

Yes, that's one of the two things I'm trying to prevent.

The other is that if I'm comfortable in my living room (which also has a
wood-burner) there's no need to keep any of the rest of the house heated
by the boiler. Because I'm not in any of the rest of the house

I'd like to add a room thermostat in the living room [running additional
wiring isn't an issue] but need to know if it can simply be put in
series with the timer-control.

That should work boiler will only fire when the timer is on and the
'stat says cold. However I'd fit a programable thermostat rather than
the simple on/off kind.

Do you mean different temps at different times of day?

It'd wire in just like a normal stat but the boilers heating time
switch would be set to constant giving the programmable stat control
of the temperature for each time period. Programable stats often
preempt the first target temperature of the day. Turning the boiler
on just early enough for the target temp to be met at the set time.

Ideally, I'd have zoned stuff, so for example the bathroom was heated at
6am, but the rest of the house not. However that's more ambitious than
my current project.

I realise that the heat in the rest of the house will suffer if the
living room is warm enough, but surely that's a natural consequence of
any room thermostat.

It would be more usual to put the room stat in say the hall and set a
little low (as a hall is generally cool) so it knocks off the heating
when the rest of the house is up to temperature.

I don't mind having a cold hall.

Which ever room the room stat is in it should have a radiator with its
thermostatic valve fully open or disabled. Otherwise the two stats may
"fight".

Yes, I think I'd open up the living room rad.
--
Roland Perry