Current building regs state that the system should have a working room stat, the regs also state that the radiator in the same space as the stat should not have a thermostat valve fitted.
I have read and followed the debate over room stats and trvs for years.
At British Gas and before trvs we were told to fit stats in the hall, the coolest part of the house, theory being if the hall was warm then the rest of the house was going to be comfortable. Then we were told to fit the stats in the lounge or the main living area theory being that the stat would turn off quicker and thus save energy.
Basically the government wants us all to save energy so anything that stops your boiler running too much they conclude will save energy and save you money. A stat is simply a switch, just like your light switch, it turns the boiler on or off, only it does this according to the temperature directly around it. If you turned the stat down completely the boiler would hardly fire up you would be freezing cold but you would be saving money, if you turn the stat up full you would be red hot but skint. Personally I think there is too much debate over stats and controls, just reading the posts in this forum I see people worried that their boiler has been fitted incorrectly or there is a major fault because there is no stat, but all the stat will do is switch the boiler on or off according to the temp near it. A stat is not a magic energy saving cure all invented by the government it is simply a switch that regulates the temperature of a given space around it. I can give a recent example where a customer complained of rising gas bills and radiators too hot.... turns out she had the radiator in the hall removed when decorating and it was never put back because the house was "still lovely and warm without it" however the stat would hardly ever switch off because there was no heat source nearby to allow it to get to the set temp.
