So now the cold weather is really with us, I decided it was time to commission the Screwfix towel rail I fitted way back at the start of the summer.
One of the two entries for the valve tails won't stop leaking despite copious amounts of thick PTFE tape (attempt 1) or PTFE paste (attempt 2) it doesn't feel like they're tapered threads , so usually I'd expect that a doubty/o-ring seal is what I'd require. As the valve are on the heating pipes and live, I don't really have the option to go for another style of fitting.
What's the best thing to clag it together with?
I had exactly this issue with 5 normal rads I fitted on Sunday. Why oh why rads are designed like this i'll never know. After seeking some advice, I just went with a few turns of PTFE tape at the beginning of the thread and progressively put more wraps of tape further up the thread. This way it tightened up against the thick wrap of ptfe tape. no leaks (as of this morning anyway).
I'm no plumber but I think the answer is as above, more PTFE. Hemp & jointing compound is used on the old threaded steel pipework & has more bulk but I'd just be wrapping a load more PTFE around your joint.