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 have never been particularly impressed with them. They cease up during
the summer and require persuasion to work properly again every winter.

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.

Increasingly you can get wireless room thermostats that you can carry
round from room to room and has smart start that calibrates itself so
that if you specify a temperature at a given time it puts the heating on
in advance to hit that target set point based on ambient temperature.

Some will even let you control your heating over the web but beware of
those with a tie in to some server or other that may vanish if the
supplier goes bust or gets taken over.

--
Regards,
Martin Brown