Thermostatic radiator valves are fitted on radiators and convectors to regulate room temperature. The valve functions automatically and is comprised of two parts: a sensor and a valve casing. The valve casing is fitted either directly onto the radiator or onto the radiator supply pipe. The sensor is fitted to the valve casing.
The sensor can have either a built-in or remote sensor. Remote sensors can be used if the radiator is located behind a screen/cover, which would otherwise cause inaccurate room temperature readings if mounted directly on or by the radiator.
The sensor functions by way of a gas-filled bellows. The gas heats up as the room temperature rises whereby the gas expands. This causes a pin in the valve casing to move, reducing the flow rate of water through the radiator. The distance between the pin and bellows can be altered by turning the sensing element, which correspondingly alters the room temperature set point.
The valve casing can be supplied with a valve limiter that limits the maximum flow rate of water through the radiator to ensure a reasonable cooling of the water even when the radiator thermostat calls for maximal heat output.