Finding pipes in wall to epipe a 2 story

I repiped my single floor on a slab by going up into attic with no major problems. I am going to repipe my son's two story on a slab. How can I determine where the pipes come up from the slab to the first floor and where the pipes are routed to go to the second floor? I was told there is a method plumbers us to locate the pipes in the wall that puts a voltage on the pipes and then a device similar to a stud finder is used to locate the pipes in the wall.

Any information any one can give me to locate the pipes from the slab and then up the walls? Naturally, the objective is to minimize drywall openings to locate the pipes. Thanks, paul

This may help if you have metal pipes: http://www.lowes.com/lowes/lkn?action=productDetail&productId=98789-317-60276&lpage=none

I have one, it's come in handy a few times.

This may be a silly question, but........ what difference does it make?

Just realize you are going to patch walls and open up the sheetrock.

Re Pipe

The only repiping I want to do is to bypass the pipes that go from the water heater down into the slab and back up through the slab into the kitchen and the bathrooms down stairs. If I can find the pipes as they come up from the slab and before they go up the wall to the second floor, then I can run new copper pipes from the water heater which is in the garage to these locations. I would not need to touch any pipes on the second floor. Neighbors on either side of us have had multiple slab leaks and I want to eliminate these under slab pipes before I have my own set of problems. A plumbing company quoted $7500 just to get rid of the under slab piping.

location

Professional locators will induce a signal into the pipes and then search for it with a sensor. DO NOT electrify the pipes and try to find them with a voltage tester. One problem is that since the pipes are all interconnected, and grounded to the electrical system, it may be difficult to differentiate between the water pipes and the electrical system.

slab piping

Thanks for the note of caution about putting an elect chg on the pipes---I was assuming the plumbing experts had a low voltage technique that would not be of any danger to anyone----sort of like a continuity test one would do with elect wiring.

Anyway, my next idea is to determine the most logical location for pipes to come up from the slab and up to the second floor and remove the floor molding which is 3.5 inches high and cut away the sheetrock behind but below the finished edge of the molding to see if I can see the pipes coming up from the slab. Thoughts anyone? Any other ideas to locate the pipes behind the wall without making too big of a sheetrock mess?

An infrared camera after you've run hot water, but finding one you can borrow or rent might be hard. Best done on a cool or preferably cold night to show the most contrast. Got a friend on the local fire department?

So you only want to replace the pipe that is buried in the slab, correct?
Where do you plan on putting this new pipe? If it's inside the wall, then that would require drilling thru each stud in the wall along the run. So your gonna demo alot of wall anyway. Or are you gonna go outside the wall and then box it in?
Chances are that the upstairs pipes don't even go into the slab. They could come out of the water heater and go straight up to the second story, and then to the fixtures.

Slab pipe elimination

Yes, correct---I only want to replace the slab copper piping and I am hoping that the pipes go up from the water heater to the upstairs---I have not opened up the wall yet in the heater area to see the pipe routing. As far as sheetrock demo, I might be able to run the new lines through part of the way to the kitchen and downstairs bathroom along the length of the floor joists of the second floor with just some access holes in the ceiling of the downstairs for working and pipe supports.

I will be starting this project in a couple of weeks. I will start by capping off any copper pipes going down from the water heater towards the slab and then see what still has water and what does not. That should be a good indicator of how much frustration and drywall repairs will be required. Right now I am planning on doing everything from the inside rather than going outside even though going outside might be easier--but I do not think going outside along the wall and covering the pipes would look acceptable---we live in southern calif so frost is not an issue.

paul housedok said:

but I do not think going outside along the wall and covering the pipes would look acceptable---we live in southern calif so frost is not an issue.

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Naw, it looks fine. You box them in with aluminum and paint it the same color as the house. Look around, I'll bet you'll see that everywhere.
I have 3 runs of pipe myself: One for the pool's solar panels, one for the water heater's solar panel, and one that contains all the plumbing for the air handler that is in the 2nd story.

pex

Thanks for the info on running pipe outside but my "customer" says no -- so, it is inside the house pipe runs----also, I checked our local building permit dept and they tell me they approve of pex currently only for commercial applications and on a case by case for residential if I file for a variance and document why I want to use it which also means a building permit process for sure.

Finding supplies around here for pex is also a challenge. Looked on the internet and found sources but when you need a fitting, it sure would be nice to run to the local HD or Lowes---but not here.

So, I have to make a decision to go ahead with pex or to go with copper.