Compression Valve keeps leaking??

[1bit]

As you know I have been doing some plumbing and started soldering for the first time, Iam pleased to announce that all my soldered joints were spot on and didnt have one leak


I have come across a new problem though, this is the 4th radiator I have installed in the house (along with many compression fittings) and one of the valves compression fitting just keeps leaking? I have tried everything, less PTFE, more PTFE, PTFE arpund the olive and end of pipe lol... I even replaced the section of pipe so I could put a new olive on and result was the same, I have re-fitted the new section 3 times (previous one 5 times) and can not stop it leaking? - the threads are fine, theres no damage and no dirt in the threads either? I normally apply PTFE around the threads in correct direction (clockwise) about 3-4 times around the threads...all other valves & compression elbows/couplers have been fine? - with this I have tried no less than 3 and tried much more..several times.


I have noticed that all other valves seem to tighten in manner that the Nut is circa 4mm from the base of the threads, but on this one it gets almost 1-2mm from the base - its screwing much further in that the others?


the water is definitely coming from the threads and not any other part of the valve or from the back of the nut.


Can anyone offer up advice for this? I mean Im gunna keep having to replace the bit pipe so can put new olive on and that requires melting solder to get it free!




thanks

 

[WaterTight]

just put ptfe on olive and try a new fitting

 

[WaterTight]

but duff comp fittings are pretty rare. a correctly compressed olive on undamaged pipe with ptfe round the olive will be water tight even with the cheapest nastiest fittings available

 

[Crinkmeister]

You shouldn't use ptfe on threads of a compression fitting and tbh, you shouldn't need it on the olive either. Have you got any jointing paste? That usually does the job for me, but you only need a small amount as the seal is made by the olive in the fitting. Don't overtighten either!

 

[1bit]

are you supposed to put PTFE around the olive anyway?
also, how many lots/turns of PTFE tape is the norm? ( I read 3 somewhere)

I think on my next attempt I will use a different NUT, the one supplied is chrome to match the valve, I will just use a brass one with PTFE on Olive too and see what happens

EDIT: Crinkmeister just read your post... your not supposed to use PTFE tape on Valves??? I thought your supposed to? sure instructions for the rad (or one of them) said to use PTFE where there is no seal

 

[heliotrope]

I think that the obvious answer now is to replace the rad valve as the existing one
would seem to be at fault.

Keep PTFE tape well away from any compression threads as this will do absolutely
nothing for the joint. Compression relies on the olive to pipe and not the threads.

 

[villa_tom]

are you supposed to put PTFE around the olive anyway?
also, how many lots/turns of PTFE tape is the norm? ( I read 3 somewhere)

I think on my next attempt I will use a different NUT, the one supplied is chrome to match the valve, I will just use a brass one with PTFE on Olive too and see what happens

EDIT: Crinkmeister just read your post... your not supposed to use PTFE tape on Valves??? I thought your supposed to? sure instructions for the rad (or one of them) said to use PTFE where there is no seal

Just put ptfe on the olive and a smidge of jet blue or something like that. I wouldn't use a brass nut on a chrome fitting. It will look naff.

 

[JCplumb]

I'm pretty sure that I was taught to put PTFE on olives of compression fittings at college. But in practice when I first started out I used to get leaks on compression fittings quite often. For the last few years I haven't used anything on the olive and had a 100% success rate.
My advice is no PTFE, don't gorilla the fitting either, make sure you're holding it with grips/pump pliers/adjustables whatever so that when you tighten the conex nut you aren't putting any strain on the other end of the fitting.
Try getting a spare piece of copper and tightening a compression fitting on to it. Hand tighten it then give it 180 degrees nip up, then undo it and look at what has happened, you'll see that the pipe has been squeezed by the olive biting into it, that will have formed a good seal and PTFE will just be unnecessarily adding something to the mix that could go wrong.
My rule of thumb for olives is as follows - others disagree but this has worked for me.
Brass olives - I only use on chromed pipe and I gorilla them.
Copper olives - everything else and i don't gorilla them.

 

[Mike Jackson]

EDIT: Crinkmeister just read your post... your not supposed to use PTFE tape on Valves??? I thought your supposed to? sure instructions for the rad (or one of them) said to use PTFE where there is no seal

The bare thread that goes into the rad will need ptfe tape. I apply 7 wraps and a small smear of joining paste, you will see people advocating a lot more turns than that but I find it all tends to push out then. On a compression fitting putting tape on the thread will make it more likely to leak as this is not where the seal is made and you are making it more difficult to tighten. The seal on a compression fitting is made on the olive. These are designed to seal without any sealant but a small wrap of ptfe or a smear of paste around the olive won't hurt.

 

[AMGasServices]

Lets go back to the basics

is the pipe long enough and does it go in all the way in to the fitting ?

 

[glenno1]

Are you sure the leak is not above the valve nut (ie the rad tail)