Strange lockshield valve

[peterf]

We've moved into a 1970 house with steel radiators, but the lockshield valves are not the modern type with a shaft. They have a plastic cap over a flat, black plastic insert with a hexagonal hole in it. I assumed it was closed with an Allen key, but it doesn't turn far and doesnt appear to affect the flow.
DOES ANYONE KNOW HOW THESE WORK?

 

[Centralheatking]

post a piccy and we all can have a look

centralheatking

 

[peterf]

This is it. Any ideas?

 

[Centralheatking]

Looks like a rad valve with all its guts taken out - the plastic cap resembles the manual closure cap for a trv when the rads are taken off.

Cant help - but if it works there is no problem

centralheatking

 

[cjg]

looks like a cast insert, rad spanner to screw it in closed,unscrew open, simples, mercat.com

 

[ferret]

looks like a danfoss allen key type and it should screw all way in to shut and level with top is fully open , if its not moving much replace it as next it leaks!

 

[peterf]

Thanks, ferret, that has clarified it and solved my problem.

 

[fuzzy]

does a rad key fit????????

 

[peterf]

No, but a 6mm Allen key does.
Ferret has solved the problem for me.

 

[ferret]

happy to help