Radiator Valves

What Is a Thermostatic Radiator Valve?

Thermostatic radiator valves (TRV) for a central heating radiator actually consist of a pair of valves. First is the TRV control valve. This contains either a liquid or wax sensor that expands or contracts to automatically regulate room temperature. As the room gets colder, the sensor material shrinks allowing the valve to open & the hot water in your central heating system to flow into the radiator, heating the room. As the room warms & reaches the pre-determined adjustable temperature setting on the valve, the sensor expands to gradually close off the valve & maintain a constant, comfortable room temperature. Each radiator contains just one TRV, the second valve of the pair being a lock-shield valve situated on the other side. The job of the lock-shield is to balance each radiator on the system to ensure an even flow around the house (or each circuit); it is also used to isolate the radiator for maintenance. To isolate the TRV, you may need a decorators cap to lock off the valve. The reason for this is that most thermostatic radiator valves have frost protection functions, meaning that they allow liquid to seep through & so must be fully locked off if the radiator is removed.