i bought a Drayton TRV4 + lockshield set, and found the lockshield is
pretty much the same valve body as the TRV but with a plastic head
that acts as a manual valve, operating the valve plunger as you turn
it.

This surprised me - shouldn't the lockshield be set using a tool, with
a cap that doesn't operate the valve? This one seems to make it too
easy for someone to open/close the valve and unbalance the system.

I think I'll go and buy a more usual lockshield to use instead.

In article om,
writes:
i bought a Drayton TRV4 + lockshield set, and found the lockshield is
pretty much the same valve body as the TRV but with a plastic head
that acts as a manual valve, operating the valve plunger as you turn
it.

This surprised me - shouldn't the lockshield be set using a tool, with
a cap that doesn't operate the valve? This one seems to make it too
easy for someone to open/close the valve and unbalance the system.

I don't know what kit you bought.
However, a Drayton TRV4 includes the flow setting for balancing
purposes in the base of the valve anyway. You need a special tool
to set it. See the TRV4 instruction leaflet. I think most people
ignore it and use the lockshield for balancing.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]