A TRV adjusts flow in response to room temperature. The lockshield is generally set during system balancing.
Thermostatic Heads, Lockshields and Valve Pairs
The valve at a radiator determines how water enters or leaves it. MacBlair lists angled and straight 10mm and 15mm radiator valves, thermostatic radiator valves (TRVs), replacement TRV heads, lockshields and towel-radiator valve pairs. Choose the connection shape to suit the position of the supply pipework, not simply the finish.
A TRV responds to room temperature by adjusting flow through the radiator. The lockshield on the other side is used during balancing to regulate the circuit. If only a head has failed, check that a replacement head fits the existing body before buying a whole valve. Straight and angled pairs are also listed for heated towel rails.
Before draining a radiator, check the connection size, valve orientation and whether an extension tail is needed. A heating engineer can balance the system after replacement, particularly when several valves are changed at once. Valve choice also needs to work with the overall boiler and heating setup.
Radiator Valve FAQ's
Choose the shape that connects your pipe approach to the radiator tapping without forcing the pipework.
Yes for compatible models. Check the head’s fitting and manufacturer specification first.
They control water flow in a similar way, but the connection layout and finish may differ. Check the rail and pipework.
Match the pipe and radiator connection sizes, which may differ. The listed range includes 10mm and 15mm options.