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What is a lockshield valve?

What is a lockshield valve?

The lockshield valve is the valve on a radiator that is usually covered with a plastic cap.


The term “lockshield” means that once adjusted, the valve is shielded with the plastic cap that prevents it from being accidentally changed.

Removing the cap reveals the top of a spindle, which usually has two straight sides at the top to take an open-ended or adjustable spanner.


Spindles on some older radiators may have a square or half-moon shape. The spindle is turned with the spanner to adjust the flow of water through the radiator.

The lockshield valve needs to be adjusted when ‘balancing’ radiators in the various rooms. 


If a radiator is taking too long to warm up, it needs more hot water flowing through it. This means that the lockshield valve should be opened to allow the radiator to fill faster. 

If a radiator gets hotter quicker than others, then the flow through it may need restricting. To do this the radiator’s lockshield valve should be tightened to reduce the flow of water. 


The benefit to using lockshield valves on radiators is that you can easily control whether you want particular rooms to heat up faster than others.

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