If you want a thermostat temperature control for the heating

[SilverHawk]

Where do you put it?

Usually in the coldest room, eg hallway. So DH says. He's a tradesman, so should know...

I know that's the normal place but in the winter the hall and landing are such a big void to heat that we switch to a doors shut house.
Where would be the next best?

Modern thermostats are wireless and portable so you can move it from room to room with you (although we got fed up with that and fixed ours to the wall in the hall)

in the living room that you use most, provided that room does not have another big source of heat such as a stove or open fire.

you then adjust the lockshield so that room warms slower than all the others.

The others should have TRVs so they will reach and not go above their target temperature.

By the time the thermostat room has reached target, all the others will already be there.

The thermostat room must not have a TRV on its radiator.

It is an advantage to zone the upstairs and downstairs individually, as your usage pattern may be different so you may want the on/off times and the temperatures to be different. This does cost more, though.

Modern digital stats have little hysteresis and will maintain the set temperature very accurately, without swinging up and down much.

Piglet John, you make the whole process very simple to understand, thank you. Everything you say makes perfect sense.
However, all our radiators have TRVs, would anything be gained from introducing a thermostat into the house? Also, one living room has gas fire hardly ever used, the other a woodburner. Guess which room is used in the winter....

yes, it would.

With no thermostat, you boiler will constantly be heating itself up and trying unsuccessfully to pump hot water around. Hopefully it has a bypass valve, so the heat will be escaping from copper pipes, probably under the floor, from the boiler casing, and out of the flue to warm the sky. This is very uneconomical.

Additionally, if you have turned the boiler off manually because it isn't cold, it will not automatically come back on when the temperature drops. This is uncomfortable.

If you are going away in winter, and want to leave the heating on low to keep the house dry and prevent frost bursts, as required by your insurance company, it will be quite difficult to arrange.

You can get programmable stats now, which allow you to set different temperatures according to day of week and time of day. If you have fires in your living rooms, put the stat in another room that you will want to be heated all the time. The nearer it is to your boiler (or possibly your airing cupboard) the easier it will be to run the cable. I am not fond of wireless stats as they go wrong more often.

The boiler does constantly fire up but I always thought that was because it was struggling to heat the house .
The second point of manual doesn't bother me/us as we use the timer.(and we're tough old things)
The third point about winter absences is a very good one though. Sooner or later boomerang DC will move out :) and we do like winter travel.
When the upgrade is due, I think that the stat would be best in the breakfast room (near the boiler). The boiler is now 20ish years old and I'm planning ahead.
Thanks for your help, I am now quite clear that it is beneficial and not just something else to go wrong.

Greatly simplified:

if the house is not adequately heated and the boiler keeps going on and off, then the radiators are too small (or the TRVs are set too low), because the radiators are not capable of delivering as much heat as the boiler can supply. An old system might have a worn-out pump or sludge and sediment obstructing flow. These can be fixed.

If the boiler keeps trying to heat the house even when it is fully warm, you need a room stat to stop it wasting gas.

Rather than going on and off frequently, which is uneconomical on gas, modern boilers modulate their power up and down according to demand, so once your radiators are all fully hot, and the rooms are at target temperature, the TRVs will start to close, reducing demand, and the boiler will try to turn down the flame size accordingly, until the house is fully warm and the room stat turns it off.

There is an advantage in having oversized radiators because they can heat the room faster when it is fully cold, and they maintain a more equable temperature. TRVs prevent them from overheating the rooms.

The TRVs are set low deliberately. DH and I have just been to visit our respective parents and their houses are so hot. We felt like nodding off!
We fall into your first reason.
Should the central heating need an overhaul, I will bear all that you have mentioned in mind. I'll also be measuring the rooms for cubic m or feet and putting in oversized radiators.
When we moved into the house it has two radiators that were being run off a back boiler. Tough people.

I've just done your very useful questionnaire that you included on another thread. It seems we need 46.3kW and we have between 17.58 and 23.45kW.
Wow, when then boiler does go, not yet, please we will definitely need an upgrade.

46.3kW?

Sounds very unlikely.

How many rooms does your hotel have?,

I seem to have gone very wrong in the calculations . Good job I'm not a heating engineer.
I hope that it's unlikely!
Back to have another go.

I've come up with 86.6kW this time :o It's getting worse. If I lived in a castle or something, I wouldn't mind.

print off the calculation and study it and re-check the input. Perhaps you have entered "feet" measurements instead of "metres" or omitted the loft insulation.

85.3 Aggh