most TRV s you turn the stat right down to 0 then under the TRV head undo the knurled head and lift the head off, you then fit the ring cap that was supplied with the TRV on to the exposed thread, this cap is supplied for decorating purposes it prevent the TRV s needle valve pin lifting up and allowing water out.
On the other end of your rad remove dummy cap,then turn spindle down with a spanner counting the turns down till tap is closed . you are now ready to drain the possible rusty rad water into a shallow dish old towels are recommended.
wirecutterman, October 2010
