Leaking Compression Fitting

Old 10-14-05, 12:07 PM
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Angry Leaking Compression Fitting

Hello All :-)

Ok, I'll make this simple. My sister (who lives in Florida) called me (I live in NY) last night with a problem.

To make it short and sweet, I won't talk about everything she went through, but I will tell you that she seemed to do everything right!

Here is the situation - she installed a new faucet for her tub and the (brass) compression fitting doesn't seem to want to fit on properly on the cold water pipe and it leaks. She has tried three different compression fittings, each one doing the same thing and leaking at it's base where it connects to the copper water pipe. The hot water works fine, no problems there whatsoever. She even tried using plumbers tape (even though she shouldn't) on the compression fitting, but to no avail.

ANY assistance would be apprecitated as she has spent so much time re-doing this that she is about to throw out the tub in frustration!

Thanks in advance!

Old 10-14-05, 12:47 PM
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MODERATORS NOTE: While the information contained in this post is correct as far as installing compression fittings, it is imperative that Plumbing Codes be followed. Compression fittings MUST be visible at ALL times. They cannot be installed in walls (even with an access panel) or under fixtures that are enclosed (vanities, tub surrounds etc). You have been suspended from posting for 7 days.

Compression fittings are easily tightened too much, causing drips and leaks.

At this point, with 3 different fittings in her inventory, I would guess the fittings themselves are not the issue. Check the supply pipe - is it smooth and "dent free". Is there any slag/debris on it?

When I install a compression fitting, I clean the pipe with a light brushing of emery cloth, just enough to remove the film/dirt and give the pipe a brushed shine. I install the nut/ferrule/fitting just enough that I think it won't fly off when I turn on the water. After turning on the water, I tighten the nut slowly, 1/4 turn at a time, until it stops dripping. Overtightening can be just as bad as undertightening... causing distortion of the ferrule and subsequent leaks.

With 3 fittings in her possession, I would get a couple of ferrules only... and try at least once more.

Another trick I learned on this forum is to take some sturdy string (kite string, for instance), and coat it with candle wax - wrap a few wraps of the coated string behind the ferrule - and tighten.... it acts like a packing gland, helping to prevent leaks... I've never tried it, but it sounds like it might work....

Last edited by majakdragon; 10-15-05 at 12:15 PM. Reason: Added Moderators note
Old 10-14-05, 08:29 PM
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After trying 3 fittings on the same spot on the copper, it is possible that if it was not damged before, it is now.

If this is the connection to the shower valve, inside the wall , you are not allowed to use a compression fitting here. Best idea is to get some sweat adapters and solder this up.

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