How to diagnose for cracks or condensation in 1/2" copper pipe

I pulled some 1/2" copper pipes upward in the summer with wire for clearance in preparation for installing T-bar ceiling tiles. I don't know that it did any damage to the pipe or joint, or even if I have more than a common situation now. I wrapped some pipe insulation, but not completely, this joint in question was tough to get to, and I left it until I was ready to finish it off. Today I was peeling back that same insulation; these pipes go to the sink and toilet in the basement washroom, and the last inch or two of the insulation was WET, meaning waters on the outside. Its been months since its been summer/humidity? in Toronto. I have taken off the insulation, chiseled off the little black rotting part of 2x4", and cleaned off the pipes, but other than the moist insulation I haven't seen any water at all, even when running tissue paper around. The water may even been wicking from down inside the 2x4" in the wall, a crack possibly on the other side of the elbow in the wall. . I don't know if either pipe is dripping from a leak/crack, or if the cold is condensing (its cold to the touch), or the insulation has just stayed wet since last it was humid, or if its bound to happen when I flush.. This pipe is at the end of the plumbing line, nothing else runs past them. The basement is where the hot and cold water are, both at the other far end of the house. The place in question is in the ceiling, running just under the first floor joists. More specifically, where both the hot and cold pipes have 90 degree elbows soldered, and where these pipes turn and go straight down into a stud wall. The drilled hole in the 2x4" top wall plate is just large enough to fit the hot and cold, each in individual holes, so nothing is getting/looking in there. The elbows are just barely solderable above this top 2x4", in fact the cold is half-buried. The two pipes are spaced diagonally, about 1" apart on centers; the pipes run very close together, both along the ceiling, and in the wall. The hot pipe is the upper one. Where the hot elbow is soldered some of the solder of that joint is actually soldered to the upper length of straight pipe of the cold.
How do I diagnose if I have a leak? I have not run any hot or cold water in the sink, nor flushed the toilet in a couple days. In the last few months I have only flushed the toilet twice, both times in the last couple weeks. I've just got tissue paper sitting there, waiting for me to look later. I could drill a hole-saw in the wall, but what about running the water, etc. to help find out. A problem is its a tight location, can't see all possibilities, and don't know how to check with a diagnosis. There are more pipes around, but they are all currently insulated.
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bent wrote:

If you used a steel wire to pull up the pipe you may have created a problem by contacting two dis-similar metals which can over time cause the pipe and wire to rot out.
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No it was 4-1/2 feet away, and already tubed in Styrofoam, taped, and strung. I wrapped that in aluminum before wiring it up. It was pretty tight up there.

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Unfortunately I had probably about as much plastic-wrapped insulation wrapped with e- tape as I could get on either side of the 2x4", and I'm thinking its just condensation. Does condensation just happen if the (cold) water is flowing? Maybe its not too bad. Maybe I can seal in the 2x4. Is this possible? I mean, normal?

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Only if the dissimilar metal is left in place or left enough residue on the copper to cause a reaction.

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snip

The only real way to find if you have a leak is to disconnect all fixtures on the line in question, cap of the ends, put a pressure gauge and an air fitting on the line, then pressurize the line with air. Wait and monitor the gauge to see if the pressure drops. This may or may not even be doable, depending on your system. But if you can, don't go too high on the air pressure, about 50-60 psi should be good. That's the check, the fix may be another story.
--
hawgeye



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I can't believe this. I've got the entire basement insulated and vapor barriered.... I'm nearly done refinishing all but the floor. I have both hot and cold pipes wrapped in newly un-glued-edge styrofoam tubes, with package taped over that joint lengthways, twisted with string over that, and used rolls of electrical tape at every corner. I have so little clearance in the 2x4 it hurts, and did absolutely everything humanly possible so its impossible for this to happen. I'm using that store bought insulation on a plastic strip too, and cut up pieces and tucked and twisted up to both sides of that 2x4" in any way possible. IOW If anybodys thinking of doing this, put the insulation tube through the 2x4, and anything else.
Now what? If I hole saw into the wall (makes for an easy patch) I have access to both sides. Silicon, or roof patch?
I'm guessing its condensation in winter. My tissue paper is dry. I have yet to run any water. I guess I can safely say that this be from the cold and only when the water runs through, enough to chill the pipe down. I wonder whats going on inside the wall? Originally I thought this almost impossible.
I wrapped the insulated pipes in a couple layers of thin aluminum sheet snipped to 3" wide, and put a screw up through the center to a joist to "wire it up" several feet away, no mistakes, no dissimilar metals.
from.... 1/2" copper pipes [with] insulation....WET> How do I diagnose if I have a leak?
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NO NO, wait sorry
I just got back to work. I'm stuffing Roxul battts b/t joists above stud walls b/t rooms for sound insulation.
I got took the tissue paper off - I looked at its outer edges before. Now I see there IS some water where I wrapped one 3/4" x 2" piece through the pipes. Like I put a single drop on the center, that hadn't reached the outer corners, or half the surface area. So I have a question for anyone with expereince/knowledge in this kinda area.
I have NOT run any water through that pipe for maybe a week. It is only uncovered of insulation a few inches on top of the 2x4 before it goes down into the wall. Only the top of the 2x4. It does feel a little cool to the touch. Nothing runs even close (w/i 12') or through.
SOOO:
Is it possible that it COULD be condensation? In winter, when its -10 degrees C outside, and say 20 degrees C inside? Or have I got a leak/ possible stress crack?
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If no water has run thru that section of pipe for days, it can't be condensation, because in a matter of a few hours, the pipe will reach ambient temperature. Condensation can only happen when the pipe is at the dew point (significantly below ambient).
Bill

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so at 18/18 and if it ain't wicking its a leak, no doubt? is what you're telling me

condensation, because in a matter of a few hours, the pipe will reach ambient temperature. Condensation can only happen when the pipe is at the dew point (significantly below ambient).
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Just in case this post is at the end of its life, a couple questions
I) Can you RE-SOLDER a elbow joint? Can I reheat the joint? Can I add solder to it? I've got a regular propane torch. Do I do the both sides at the same time, kinda working back and forth. I'm assuming I just need to shut off the main water supply, flush the toilet, and open the sink faucets.
II) If I have access to the area of the elbow/pipe that has a crack can I fix it with MAGIC PLUMBING TAPE? Is this type of product anywhere decent? If it is condensation I wonder if this stuff could help with that?
I'm still at diagnosis stage. I still have to remove some kleenex. I'm determining if its residual water (possibly wicking), or condensation. I'm checking if I can get it dry. I have yet to run any water past it.
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I think you need to call a plumber.
--

-Mike-
snipped-for-privacy@alltel.net
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that was a yes or a no, and to whit quastiasn

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I'm thinking the problem did not originate, but rather was only aggravated an older minor problem that more than likely work hardened or fixed itslef and never really became a problem. The thickness of the added tube insulation is greater than the offset I caused when I "wired it up". It is snugged up and squashed in.
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who knows it may have always dripped

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