Leaky radiator tail

5 Nov 2008
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United Kingdom
I've just fitted a new radiator but cannot stop one of the tails from leaking. It's a taper thread and I've used PTFE tape, but despite three attempts including two different tails, it still drips.
The design is such that you screw the tail into the rad and tighten a large nut on the tail onto the valve. Because tightening the nut onto the tail can undo the taper thread, I'm very careful not to overtighten it and move the taper thread.
I've never had a problem with these radiators or this tail design in the past, but I'm starting to lose patience.
Any thoughts what I should use to seal it?
More PTFE tape?
Plumbers Mait?
Silicone sealant?
Loctite thread lock?
PS it's my house so I'm not after a bodge that can't be undone!
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yes use hemp and hawk white sealing compound used to be boss white, never had any problems with leaks when using it , so give it a go

I would suggest carrying on with PTFE but ensure that you are applying plenty. Make sure that the tape is also applied with more wraps applied to the valve end of the thread. Thus creating a taper with the tape aswell.

Have you checked that there isn't a fault with the rad? Rare but possible
Thanks for the suggestions. Thought I'd try once more with PTFE tape first as I don't have any sealing compound.
As suggested I used loads of it and after 30 mins it seems to be drip free.
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I would normally apply ptfe tape around thread at least 15 times if that helps.

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