Radiator valves

[AndyPRK]

Need to remove an old radiator for decorating.

The cap on one of the valves was removed which has a screw head under it.

When turned it just leaks water out the top
What is this ?
Can the rad be turned off with one of these ?


Thanks

 

[dextrous]

It's a lockshield valve which is set when a system is balanced. Yes, a radiator can be isolated at this end by turning the screw clockwise until fully shut, but count the number of turns to give yourelf a figting chance of not losing the balanced setting.