Radiator tails - preferred sealant and depth of fit

[andreas]

I am replacing a couple of radiators with column radiators, they're mounted on the wall just need to put tails and TRV's, using Drayton TRV4 tails.

What is your preference for sealing them? I have only ever used PTFE tape before but I've been seeing people use liquid PTFE which looks a lot simpler but it is trouble-free? Anything else better? 

My main question though is that the tails do not go in so that the threads are fully hidden. There are 2-3 threads left exposed even test installing without any sealant. I don't want to over-tighten them and try and force them deeper so would like to know if that is common. The panel radiators I have put in else where the tails could be wound in by hand until they disappeared into the radiator until PTFE had been applied!

[nod]

I’ve used a paste on ours without any issues and locktite on the rad thread