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Thread: Seepage between heater inlet and dielectric nipple

  1. #1
    DIY Junior Member neil.steiner's Avatar
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    Unhappy Seepage between heater inlet and dielectric nipple

    I just installed a hot water expansion tank, as my first ever "real" plumbing job, put everything back together, and ended up with a bit of seepage after restoring pressure to the system. (I learned how to solder copper pipe from YouTube and from some of your posts, and that part is fine.) I also flushed the water heater a few months ago, and replaced an ugly anode rod with a new magnesium rod. The water heater had a bunch of sediment, but no sign of rust to my untrained eye. But that's mostly beside the point. Incidentally, this is a 66 gallon AO Smith EES 913, possibly dating back to 93, judging by the serial number.

    My main problem seems to be with the threaded female inlet to the tank. It looked ugly to start with, but it wasn't leaking.


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    After understanding what I was looking at (I think), I found myself a little dismayed at how few threads were there and at a bunch of black gunk and slightly charred dip tube. After cleaning all of that out, I took my new dielectric nipple, put a bit of teflon tape on the ends, tightened it with a wrench, screwed on my copper contraption and soldered it to the water line, and opened the valve first slowly and then all the way.


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    Even before the system was pressurized, and only exposed to the full stream of water coming in, I started seeing seepage at the top of the dielectric nipple. After consulting google, I cut my pipe, unscrewed everything from the nipple, cleaned the water inlet threads with a wire brush, and applied four wraps of teflon tape in the right direction, with pipe dope on top of it. I tightened everything down really well, giving it a full turn more than intended because of the angles that I needed to preserve to mate with the water line and my expansion tank mount. I soldered everything back in place, and there was no more seepage at the top of the dielectric nipple. I let the tank fill completely with all hot water faucets off, and everything seemed to be okay until I noticed the tiniest little drop of water poking through the pipe dope at the base of the dielectric nipple.


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    All of you will know that it's difficult to tighten anything once it's hardpiped in place, but I really didn't want to cut the whole thing out again, and I was pretty confident that I had applied the tape and dope correctly, and had tightened things sufficiently. Nonetheless, I heated up the tee fitting just above my threaded female adapter, and forced most or all of another turn with an 18" wrench while the solder was molten. I turned everything back on, and found the same seepage.

    Now the water header is quite old, but I've seen no problems with it in the year-and-a-half that I've owned the place, and I'd rather not replace it just because of a problem with a fitting. (You will be amused to hear that I decided to do all of this myself because I wanted to save some money!) So I thought to myself, why not use JB WaterWeld or JB MarineWeld? I could try to sand down the top of the water inlet fitting and permanently glue/weld that to the dielectric nipple. The pro is that I wouldn't have to cut out my pipe and rebuild it yet again. The con is that access is poor (the brown cover isn't centered over the fittings), and I'm not positive I would be able to clean the surface sufficiently. But another option that occurred to me was to use Loctite (the red permanent stuff). I would have to cut my pipe out, and I would be attaching the nipple permanently to the tank, but if it got rid of the seepage, I'd be satisfied.

    By the way, my hat is off to your profession and the crazy things you have to deal with.

    Any thoughts on what I can do about this? I think my problem stems from an old and damaged fitting on the tank, so I probably wouldn't experience this same thing on a new water heater, but I'll admit that I'm now far less confident about these jobs.

  2. #2
    Test, Don't Guess! cacher_chick's Avatar
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    I would start by running a thread chaser or tap down the fitting to clean the threads, and then instead of re-using the possibly bad fitting, I would use a brass nipple with good quality pipe dope.

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    DIY Junior Member neil.steiner's Avatar
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    @cacher_chick, brass because it's softer and would deform better (or rather conform to the female threads)? I could do that, but it would leave me without a dielectric nipple unless I want even more threaded connections in the system, and those have seemed to be the source of my problems. It's true there was no dielectric nipple in place before, but I didn't want to be doing something stupid by leaving it out.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Brass next to steel between copper should be fine.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Junior Member neil.steiner's Avatar
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    @jadnashua, understood.

    @cacher_chick, your suggestion is certainly better if I hope to remove and replace any connections in the future, but this water heater is almost 20 years old, and I probably won't be doing anything else to it until it fails. What if my objective were to most easily and effectively squash any leaks? Or do you not think the Loctite would accomplish what I intend?

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    Test, Don't Guess! cacher_chick's Avatar
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    The only guarantee with something like JB-Weld is that it would be a hell of a lot harder try something else when it still leaks.

    The brass nipple accomplishes the same thing as a dielectric nipple, but the threads as you suggested are more likely to conform to any flaw in your heater's threaded fitting. It is also more beefy, so you can use a sizable pipe wrench on it to get some leverage. Just don't twist it in hard enough to tear the top of the tank open.

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    DIY Junior Member neil.steiner's Avatar
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    @cacher_chick, thanks again for your suggestions and explanations. After opening everything up again (routine for you guys, but traumatic for me), using the pipe tap as suggested (it helped but couldn't go deep enough), I took a really good look at what was left of the threads. At the narrowest point, there were only two solid threads in place, exactly where my previous seepage had been. I hemmed and hawed but in the end decided that pipe dope would probably loose that battle and JB MarineWeld would be too thick to get between the threads.

    So I used a brass nipple as you suggested, covered the threads with loctite 271 (red), and screwed it in as tight as I could. I soldered everything back together yet again, and kept the water off for the full 24 hour cure time. When I sheepishly turned everything back on--with a mind to do some serious flushing of the tank--there were no leaks. I'm still monitoring things, but I've found no problems yet.

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    In the Trades Towers Plumbing's Avatar
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    Consider too, that once heat is applied to those fittings with the water heater lit, you will get some pipe expansion which in alot of cases, can cure minute drips on threads.

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    DIY Junior Member neil.steiner's Avatar
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    @Towers Plumbing, I see what you mean: If the expansion did block the leak, it would probably continue to do so as long as the water was hot. I suppose I was afraid of betting on that as a solution.

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    DIY Junior Member neil.steiner's Avatar
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    One last question for everyone: There was previously no bonding wire between the hot and cold water pipes, but I have been led to believe that putting a bonding wire in place is always the right thing to do. Any disagreement?

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    Forum Admin, Expert Plumber Terry's Avatar
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    Incidentally, this is a 66 gallon AO Smith EES 913, possibly dating back to 93
    The water is 19 years old?
    It's a good thing you DIY'ed it. I would feel pretty bad charging someone to work on a nineteen year old tank, when it could go at any moment.

    You may want to ask in the electrical forum about the bonding. We normally see the pipes bonded, but not being a sparky and on site, it hard to tell if it has been bonded "somewhere".

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    Test, Don't Guess! cacher_chick's Avatar
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    Most homes these days have a single handle tub/shower valve which effectively bonds the hot and cold sides together. Because of the use of plastics in many water systems today I believe that the code requirement to bond the plumbing system is a thing of the past.

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