Leaking tower radiator valves

[Hugo67]

Hi there,
Hoping someone can help.

I’ve got a tower rail radiator in my bathroom, with two similar looking valves at the bottom.
I turned the heating on and that radiator wouldn’t heat up (similar one in the second floor heats up so I think not an issue with pressure in the system).
I therefore unscrewed both valves (like half a turn each) and water started leaking from both valve caps.

I can’t remove those round shiny caps to see what’s up with the actual valve underneath. How should I do that? Also should I turn water off or the heating off before trying that?

And finally, was I not supposed to unscrew both valve tops to get the heat started?

Thanks!!

 

[oldbuffer]

1. Has the radiator ever warmed up, because if not I would suspect someone has closed the valves to stop them leaking.
2. That type of valve is of generally poor quality, and would probably best be replaced.
3. To get at the "innards" you have to remove the thin disc covers on the ends of the control knobs. The discs have a tiny screw thread attached to the inside, which screws into the spindle of the valve. In my experience they snap off as soon as you try and loosen them.
4. Even if you get at the internals, the spindles are usually sealed with O rings and cannot be packed with PTFE tape to seal them.
5. To change the valves I'd advise you to drain the system unless you really know what you are doing.