Individual room controls allow different temperatures to be set in each heated room. In a central heating system with radiators these controls are usually Thermostatic Radiator Valves (TRVs), which fit onto the connection between the radiator and the heating pipework.

Many homes still have manual valves fitted to radiators. Upgrading these to TRVs allows each room to be set at a temperature to suit the occupants, or lower if not used regularly. They prevent the room from overheating and stop the boiler from heating a room that is already warm (even responding to winter sunshine).

Data from tests by Salford University, on behalf of BEAMA and BRE, showed that correctly set Thermostatic Radiator Valves in rooms other than the living room could reduce energy use by 18% by preventing unnecessary overheating in those rooms.

Installation

TRVs can be fitted to all radiators, expect any in the room where the room thermostat is located. It is now a requirement in the building regulations that these are added when a boiler is replaced. You can also get this work done separate from a boiler replacement, and until March 2027 this would be eligible for 0% VAT.  

It may not be practical to fit TRVs to some older radiators. If this is the case it is worth considering replacing the radiator, as it is likely that there may be other issues affecting the performance of an older radiator, and therefore the effectiveness and efficiency of your heating system. You should ask your installer to select TRVs with the ‘Keymark’, which shows that they are good quality controls that have been subjected to a number of tests for performance and reliability.

Where you have TRVs that have been there for many years they should be periodically checked to make sure that the TRV is not jammed, and that adjusting it directly affects the radiator heat output. Generally speaking it will be economically beneficial to replace any existing TRVs over 20 years old, even if they appear to be fully working, due to technology advances.