Radiator valves perform the function of controlling temperature, and they feature in pairs on radiators.
One valve, commonly referred to as the control valve, is used to turn the radiator on and off. It can also mediate the amount of water entering the radiator to influence temperature.
The other valve is the lockshield valve, which is used in the balancing of radiators within a heating system.
For a more detailed insight into radiator valves on the whole, explore our Radiator Valve Guide.