What Is a TRV or Thermostatic Radiator Valve?

A Thermostatic Radiator Valve (or TRV) is a valve which is fitted to a radiator in a hot water heating system that is self-regulating (sets the temperature of the radiator automatically) based on the temperature of the room. It controls the room temperature by altering the flow of hot water to the radiator.

In simple terms, it is a valve that can be set by the homeowner to turn on and off the radiator (when the heating system is active) based on the temperature of the room. This allows a level of temperature control in every room of the house, which one would not normally be able to achieve, even with a thermostat controlling the main heating system.

Building Regulations state that all new and modified wet central heating systems must have a TRV fitted to every radiator (apart from one where the room thermostat or programmable thermostat is installed, typically in the hall)..

They were invented in Denmark and started to be use initially in the 1970’s. In Europe they are widely used, particularly where it is common to have a shared boiler supplying heat to all the flats in a block. There is a need to control the heat into each separate apartment and this is done very effectively with the use of these thermostatically controlled valves fitted to each radiator.