Bodge fix to slow leaking radiator connection -better rad on or off and plumber mait? denso tape?

[Madrab]

Did something happen to the connection was it knocked/banged with something to make it leak? You could try backing the nut off half a turn and then re-tighten, it shouldn't make things worse but may be all it needs. If that doesn't work then chances are something more substantial is wrong and it needs properly repaired.

 

[Dereekoo]

Thanks - so no point trying plumbers mait or denso? Only trying to slow it down....
I do have some basic plumbing skills - I would sort this for my own home..and do it properly -be ready to redo the joint completely. Just don't want to make the situation worse.
I know if I overtighten it and squash the olive it will leak even worse or as I don't know the history and feed is a short length out of the floor if it has been bodged in the past (eg from experience the feed pipe is only just long enough, just hanging on and drops down as soon as disconnected although that was microbore not 15mm ) the valve could come off altogether and lead to a massive flood! Both of which would lead to us losing the heating altogether.
Draining this system (16x 2m radiators) would be a big job ...even isolating all the rads before draining so connecting pipework only would still contain a huge amount of water...sure it would take a couple of hours to drain, refill and get up to temp.
I suspect if a plumber does need to redo the joint if he can he will try and do it without draining - maybe try to freeze the feed or hel look at doing it quickly whilst being ready to drain if needed.
I guess I will just keep topping it up and keeping my fingers crossed...
thanks everyone....

No need to completely drain the system, just depressurise it and shut valves at both ends of radiator. Then the bottom nut can be released and if possible (since you cannot drop the feed pipe down) lift the end the radiator up so the olive on the pipe is accessible and then wrap 5 turns of PTFE round it, offer the joint back up and retighten. Not withstanding a few dribbles and assuming at least one of the radiator valves fully isolate, the water will remain in the system because there is no atmospheric pressure to push it out (think putting a straw in water and the lifting it out with your thumb on the top of it). Obviously have everything ready to hand with a towel handy as well and work quickly, done this procedure a couple of times when I needed to replace a dodgy valve (even on a gravity system with a couple of carrots stuck in the header tank pipework to prevent atmospheric pressure coming into play.)