These valves control the flow of water through your radiators and are situated at the bottom, where the pipe feeds into the unit.

There are three different types of valve:

  • Thermostatic radiator valve

Using air temperature sensors, Thermostatic radiator valves (TRVs) automatically regulate the hot water flow. You can adjust the temperature through
a series of settings from 1 (the coolest at around 10°C) to 5 (the hottest at around 23°C), or switch them off using the * setting, which will stop the radiator from heating up, but allow enough warmth to ensure the pipes can’t freeze.

  • Manual valve

A more basic version of the modern TRV, manual valves are generally found on older heating systems. Rather than being self-regulating, they operate on an open/closed basis, either allowing hot water to flow through and heat the radiator, or stopping the flow to allow the radiator to cool.

  • Lockshield valve

Located at the foot of your radiators, on the opposite side to the TRV or manual valve, lockshield valves are covered by a removable plastic cap and require a spanner (or similar tool) to open (turn anti-clockwise) or close them (turn clockwise). They rarely play a part in controlling heating systems anymore, due to the introduction of TRVs.