heating coming on when it's "off"

[MarvellousCake]

Thermostat switched to "night" ie 12c. Radiators are warm in the morning. Thermostat is reading the correct temperature (around 18-19c). Thermostat seems to work, ie we can make the heating switch on by increasing the temp to, say, 20c, when it's off. And can turn it off. But any thoughts about why we might have warm radiators in the morning? Is it possible for someone else's thermostat to interfere with ours? We are semi-detached with boiler on ajoining wall.

Is the heating coming on with the hot water? If so I think it might be that the divertor valve is stuck.

If you turn it to 12 degrees and your house is falling below that during the night then I suppose that is why?

But if you are saying its 18 degrees when you get up then I'm stumped!

As it should only say 12????

I'm as much use a a chocolate kettle!

It's definitely coming on even though house is not below 12c. And it's not the hot water as it happens before we get up....

Is it a digital thermostat or a dial? Mine is a dial one, it kept coming on while it was still warm and well over the cut-off point of 20 degreed.

The dial had twisted round and got stuck so that the numbers didn't equate to what was happening behind the dial. Just got a new dial, which the plumber happened to already have in his van and fitted for free - result!

have you got a hot-water cylinder, or a combi boiler?

What is the make and model of your room thermostat?

is it all of the radiators which are coming on or just 1 or 2?

some bedroom ones have a TRV (thermostatic valve) which can override the main thermostat, if they have these, turn them down to 2 or 3 and that should prevent this happening.

i only know this as our bedroom one was coming on, on its own and no other in the house were - apparently it has one of these TRV thingys, having it set on '5' was meaning the bedroom one automatically came on when the temp fell to under 20 degrees!

Combi boiler. Baxi digital thermometer. Radiators have trvs (i think) but this has only been happening for a few days. Seems to be all radiators, except those which are totally off. Thanks for everyone's help/ thoughts so far!

A TRV can turn off its own radiator, but it cannot turn on the boiler.

Most likely it is a setting on the programmable thermostat. You may need to browse the instructions. If lost, you can download them from the maker's website.