Cold well water and high humidity cause serious moisture problems on wall pipes in this area of the country. Would like to develop pipe-in-pipe system to carry cold water in the core pipe and hot in the jacket pipe. Yes, there would be heat equalization, but not a problem. Where can I find such a product -- or is there a reader with experience in making such a device?

  • Actually, heat exchange is a problem. And coaxial piping is a complex, messy solution to an issue easily solved in a non-complex manner with pipe insulation.
    – Ecnerwal
    Commented Sep 7, 2015 at 15:05
  • Is there a reason pipe insulation is not an option?
    – Tester101
    Commented Sep 7, 2015 at 19:09
  • Heat exchange is a bigger problem than you may think it is. I once advised somebody to insulate a 15' run of metal pipe where the hot and cold pipes were in contact with each other. They didn't, and they always had to wait a long time for the cold water to start cooling down at the end of that run and it never really got cold if the hot water had been in use, because not only the water in the pipe was hot, but the pipe itself was hot. Commented Sep 8, 2015 at 4:03
  • The valves and junctions for such a system would be VERY complex, both to manufacture and to use. And I agree: heat exchange would definitely be an issue. Commented Sep 8, 2015 at 13:34

2 Answers 2


You should wrap the pipes with lengths of foam pipe insulation. Both the hot and cold sides.


If you don't want to do the insulation for some reason, I would recommend a gutter system. Rather than enclose one pipe in another, run a "tray" underneath the pipe. This is much, much easier to implement and maintain.

You could use rain gutters designed for the edges of roofs. Or, for more flexibility with connectors, I suppose you could slice PVC pipe down its length and use PVC elbows and tees. Slicing PVC down its length is somewhat difficult and requires the correct setup.

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