What Is Thermostatic Radiator Valves?

Thermostatic radiator valves (TRVs) do not control the boiler; they control the flow of hot water through the radiator they are fitted to. They work by sensing the air temperature around them. If the room is warmer than the setting on the TRV, the valve will close a little, reducing the volume of hot water flowing into the radiator. If the room temperature is lower than the TRV setting, the valve opens, increasing the flow of hot water into the radiator.

A radiator cover can prevent the TRV from getting an accurate temperature reading. Warm air, heated by the radiator, can get trapped under the cover, and the TRV can read this thinking the room is warmer than it is. We do not recommend having radiator covers, if possible.

TRVs can be adjusted to different settings by twisting them clockwise or anti-clockwise. They are usually marked with a scale from 0 – 6, where zero (0) is off and six (6) is fully open. Aim for the lowest setting that keeps the room to your desired temperature. A lower setting reduces the volume of hot water, using less energy and saving you money. If you’re not using a room, TRVs can also be used to either turn the radiator off completely or maintain a minimum temperature to keep the room just warm enough to prevent damp.