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What is a Thermostatic Radiator Valve?

Paul Scott
Paul Scott

A thermostatic radiator valve (TRV) is an automatic regulation valve that controls the flow of hot water through heating radiators based on the temperature in the room in which it is located. The valve typically features an adjustable temperature setting that allows occupants to select a comfortable temperature in their environment and automatically adjusts the internal mechanism, thereby closing or opening it as required. Radiator systems fitted with TRVs not only deliver convenient hands-off temperature control but also make hot water systems more efficient with significant cost and CO2 emission savings. TRVs may be used on most radiators, towel dryers, or convectors and are available in off-the-shelf or custom units.

Radiator heater systems work by circulating hot water through a radiator that features a large combined surface area through which heat dissipates into the air. The maintenance of a comfortable temperature in any space requires regulation of the flow of hot water into the radiator. One of the cheapest and most efficient methods of achieving this regulation is the installation of a thermostatic radiator valve. This device is connected in line with the radiator feed pipe and consists of an adjustable sensor unit and a valve section.


The valve sensor consists of a metal bulb filled with a heat sensitive substance such as wax. This substance will contract and expand according to the ambient temperature it is exposed to, and it is this motion which activates the rest of the mechanism. An adjustable temperature dial dictates the time taken for the sensor bulb motion to act on the mechanism, thereby allowing for a range of ambient temperature settings to be chosen. When the bulb expansion does act on the mechanism, it opens or closes the valve spindle. In this way, the valve supplies hot water to the radiator when the temperature in the room drops below the selected value and shuts it off again once the temperature has been restored.

TRVs are not only convenient but cost effective and green friendly as well. Controlling the flow of heating water is this way reduces the energy consumption of the heating system as a whole, thus saving money on heating bills in the process. The environmental impact of the system is also favorably influenced in respect to reduced CO2 emissions and fuel consumption. There are a large range of thermostatic radiator valve types available as standard, off-the-shelf units or, if an out-of-the-ordinary system requirement is encountered, as custom tailored variants. A thermostatic radiator valve is suitable for almost all water and steam radiator heater systems as well as towel rail heaters and convectors.

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