Set Square wrote:

There are actually 3 variations - but 2 of them share many common parts.

Standard manual valves and lockshield valves are the same animal but with
different plastic tops. Manual valves have a knob which you can turn - like
a tap - to open and close them. Lockshield valves have a cover over the end
of the spindle which doesn't rotate it. These are for balancing the system,
are turned with a spanner, and then fitted with their tamper-proof cover to
prevent the setting being changed.

To the extent that sometimes when you buy a lockshield valve you
actually get the valve with two alternate plastic tops. One that engages
with the valve and acts as a knob - turning it into a conventional
radiator valve, the other that is just a cover for use in "lockshield mode".


--
Cheers,

John.

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