In message , at
16:47:11 on Thu, 8 Oct 2020, newshound
remarked:
On 08/10/2020 11:49, 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.
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.
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.

Not quite the same, but I have a switch by the back door going to the
boiler "room thermostat" terminals that are normally shorted for
thermostatic rads. Electrically, it's doing what you propose.

I'll need to look a my boiler to see if it has such terminals. But
thanks for the heads-up.

--
Roland Perry