How many turns of PFTE on radiator tails

[jacoscar]

I have just fitted a radiator in my house (not the first time) and when it comes to installing the tails I never know how to make sure there is the right amount of PTFE; the tails I use are not conical and when screwed in all the way (without ptfe) they are still a bit loose
It’s the kind that you install using an adjustable wrench, not a hex key
I first tried with 25 turns of PTFE and it was leaking on one side; I took the radiator off, put some jointing compound on the female thread and then I put the tail back with 25 turns of new PTFE; it doesn’t leak now, but it’s the first time I use jointing compound on a radiator tail

When I read similar discussions online it looks like people are only doing 6-10 turns

What am I missing?

 

[Madrab]

Normal tape then 10 - 15 turns. Gas tape, which is thicker - 6 turns.

If you run the last turn or 2 just over the edge so it catches on the tapping threads when starting and don't tighten 'too much'

 

[jacoscar]

Normal tape then 10 - 15 turns. Gas tape, which is thicker - 6 turns.

If you run the last turn or 2 just over the edge so it catches on the tapping threads when starting and don't tighten 'too much'

With 10 turns, I would probably be able to tighten by hand

 

[Madrab]

Something's not right then. What tails and rad?

If it's normal 1/2" tapping and standard tails then 15 turns with normal tape should be more than enough. Some also swear by thread cord - loctite 55 to name one.

 

[jacoscar]

It is this trv+lockshield

https://www.toolstation.com/corgi-angled-trv-lockshield/p3820

And a radiator from traderadiators

to be honest though, even my other radiators are from there and I’ve used other kinds of radiator valves and I’ve always needed 20-25 turns

 

[JohnD]

does this sound like straight threads, rather than tapered?

It usually gets tighter as you go. Sometimes you need or add or reduce the tape a bit for a good position.

 

[jacoscar]

does this sound like straight threads, rather than tapered?

It usually gets tighter as you go. Sometimes you need or add or reduce the tape a bit for a good position.

definitely a straight thread on both the tail and the radiator