The thermostatic radiator valves (TRVs) were pioneered by the Danish and actually first appeared in the 1970s as a cheaper and simple way to control the temperature of different zones in a large building having what is known as a wet heating system from a central boiler (basically central heating). The TRV is also useful in offices and factories, and is very common in apartment blocks in Europe, when a single boiler that is fitted in a basement feeds lots of flats. In this case, the boiler will probably be permanently on with hot water constantly running through the pipework (the boiler is operating at its most efficient). South East London Plumbers can fit control valves. The thermostatic valve is a great alternative, because it opens and closes automatically in response to room temperature changes. These valves are usually a one for one swap with the old valves. But, before you attempt to replace them, make sure that they fit. To fit a new valve:Drain the system and remove the old valve. Loosen off the nut securing the valve to the pipe, now, undo both nuts fully and lift the valve, its cap-nut and olive from the end of the pipe. You dont need to move the radiator to do this. Clean the end of the pipe with some wire wool ready for the new valve. A South East London Plumber is trained to fit all appliances. Holding the valve in place, screw the cap-nut on the valve, and check the olive is sitting correctly. Do not tighten the cap nut completely. Use a 2 turns of PTFE tape on the threads, and confirm the valve is straight as you turn the cap nuts. Once complete, and you are happy that all connections are wateright, re-fill the system. The new valve or valves must be set up in accordance with the makers instructions. Check for leaks and also balance the radiator circuit.