People's perception of temperature is very subjective and can be affected by different aspects such as level of activity, clothing, health. For this reason an occupant should be able to control and adjust the temperature in a room easily and quickly. Thermostatic Radiator Valves (TRVs) and heads are fitted to radiators and used to provide such room temperature control. When used properly, they will significantly reduce the energy used by the heating system by limiting the temperatures within each room, and preventing overheating. Reducing the temperature by 1°C can reduce energy costs by up to 10%.

Radiator thermostats control the thermostatic radiator valve (TRV). The air passing around the sensor of the radiator thermostat causes the sensor to expand when the temperature rises. The expanding sensor closes the TRV accordingly. When the room temperature changes the TRV opens or closes proportionally. Only the amount of hot water required to maintain the room temperature set on the radiator thermostat is allowed to flow through the valve.