Our water heater will be relocating sometime in the next month from the garage to a far corner of the house, so the flow direction for the main hot water line will reverse from how it is now. I don't want to replace this pipe since it's in good condition unless I absolutely have to. It's 3/4" copper installed in the crawlspace in 1959 when the house was built. Access to the area is very good - nothing is hidden or covered up.

Is it OK to leave as-is, given that I am in the habit of inspecting everything under the house every 3-4 months and access is good?

Yes.

AggieT said:

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Yes.

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+1, shouldn't cause any issues.

I assume it's insulated?

Aggietaco said:

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AggieT said:

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Yes.

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+1, shouldn't cause any issues.

I assume it's insulated?

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Yep, when I insulated it a few years ago. It went the previous 50-something as-is with no signs of breakage or repairs.

Eh, just noticed the vintage based on your 50+ year response. Depending on your water quality, you could be getting close to the age expectancy for that pipe. Since a leak wouldn't cause you any issues except for having to crawl around in the mud, I probably wouldn't worry about it, but if there were a chance for water damage I might look at replacing it now.

If it's going to be a dead end pipe with no flow, I'd remove it simply because it's harder to keep a dead end from freezing. If it'll still have flow then I think it just becomes a matter of trusting is age. When you cut into it, check what you can see. If it looks full thickness and un-corroded leave it in service.

We won't have any dead ends - I'd planned on either swapping what's now the first "T" for an elbow, or leaving a few inches of pipe and sweating on an end fitting so the run could be extended to the den if we do any kind of a wet bar in there next year. That room will be connected more to the pool (assuming we build one) and back yard than the rest of the house.

The pipe itself is in great shape, it takes forever to cut through it compared to new copper. The fittings are more what I've been thinking about. I discovered one with an extremely slow drip while doing demo in the hall bathroom and will try and figure out what's behind it when I cut the section out. The water is soft and neutral, my guess is the damage could just as easily be from people banging it up from all the work and changes over the years than anything else.

Just re-sweat the fittings if that's all you're worried about. It would also give you a chance to check on the internals of the tubing.

Any tips on resweating fittings? That's really all the one with a problem needs, but I'm not sure how to go about doing that without first draining the line unless that's unimportant.

To re sweat a fitting it can't have water in the pipe. The water will prevent the pipe from getting hot enough to take the solder.

You'll have to turn off the water, either the cold to the house if it's the cold water or the valve at the water heater if it's the hot side. Drain the line so that there's no water in the pipe.

The best bet would be to heat and remove the joint if possible, clean both sides well with sandpaper to a bright sheen. Then flux both h sides well, replace the fitting and solder into place. Touch the solder on the side opposite the flame, the heat will draw the solder toward it. Just melt/ insert enough until you see it flow up out of the joint. Especially with re sweating, it won't take much.

What he said. The only issue with re-sweating one joint is that you may cause some instabilities in the connecting joints unless there is enough "slack" in the line.

One thing a plumber showed me years ago is to stuff some balled up white bread into the pipe ends before you start the sweatng process to keep any water/moisture away during the sweating process. Regardless of how much you've drained off and/or let it dry out, Murphy strikes and draws the moisture to the sweat joint making it tougher to get a good consistent heat transfer at the joint which can impede the sweating process.

I had this issue when I used to sweat copper in my early days but since I've learned this little trick of the trade, I've been successful ever since. The bread will dissolve and is easily flushed out the line when the water is turned back on!

I'm probably not going to use a plumber that stuffs balled up anything into any of my supply lines.

Aggietaco said:

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I'm probably not going to use a plumber that stuffs balled up anything into any of my supply lines.

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I was taught the same trick. Especially for lines that you can't keep water from getting back into your sweat joint. I almost mentioned it earlier, but I didn't want to throw someone for a loop stuffing bread in their pipes!. Depending how close a water stop is, you can flush the bread out through the supply valve once the joint is set.

Oh, for some reason I thought resweating the pipe left it in place and more solder was added or what was in there already was remelted somehow. It seems just as easy to cut out the affected joint and replace it using repair couplings with short sections of pipe?

I realized it'll be easy enough to drain the affected line since I'll have one end of it open already anyway to make the connection to the pipe that goes to the water heater. Might as well just do it then.

You can try to re sweat by simply heating and adding a little solder to the dripping side, with the water line empty of course. It's just not always an easy fix to get the solder into that dripping area. Corrosion, minerals, etc. are in that little pocket I guess and the solder doesn't always want to stick to it. That's why I mentioned just pulling it and starting over. But it won't hurt to try to heat and add a little first, worst thing is it still drips.

There are tools you can use through wyes or threaded fittings or the dissolvable pipe plugs that are just a few bucks, which seems worth it versus risking partially dissolved bread being stuck in my fixtures or aerators.

Aggietaco said:

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There are tools you can use through wyes or threaded fittings or the dissolvable pipe plugs that are just a few bucks, which seems worth it versus risking partially dissolved bread being stuck in my fixtures or aerators.

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Which is why I mentioned draining it from the closest water stop vs a fixture. Or you can easily unscrew the aerator and flush it that way if you are concerned about it being stuck in the aerator. I was simply confirming it was an old plumbers trick to stop the water from fouling up the soldering, and that it doesn't disqualify a plumber from knowing what he's doing.

^^^^^
This!