I need to detect the in-wall PVC pipes for a central vac system. Apparently one port was covered up with drywall, so the vacuum is broken and the entire system is useless. I cannot find anything for sale or any method that detects PVC pipes with no water in them.

  • 1
    Is this a new construction house or a used house where a previous owner decided to cover one of the VAC ports? If new you should be talking to the builder and his subcontractors.
    – Michael Karas
    Jul 10 '17 at 14:37
  • Use a toner to trace the low voltage wiring running with the pipe.
    – Tyson
    Jul 10 '17 at 15:08
  • Could you look in the attic for a pipe not associated with a port in the room below? Jul 10 '17 at 15:18
  • Is the central vac piping in the attic or under the floor (in basement or crawl space)? Jul 10 '17 at 15:28
  • I have worked on vacuums in the past that generated a large amount of static electricity. You may be able to trace the pipe with a non contact voltage detector. At least to the point where the large air flow is.
    – Ed Beal
    Aug 15 '17 at 19:51

Can you snake a long extension cord through the PVC pipe, run some current through it, and then use a high voltage cable finder to locate the cable in the wall?

Vacuum pipes usually don't have a whole lot of bends in them, so the snaking should be quite simple.


Central VAC lines will be arranged to be connected with minimal turns from the wall port up/down to the main line heading back to the central unit. It may even be that the main backbone of the system is a larger diameter pipe that reduces down to a smaller size at the wall ports.

If this construction exists in your case it should be possible to locate the wall branch pipes in the basement or attic. (Note it can be more of a problem if it is a two story house and the backbone piping is located between floors and feeding to wall ports on both the upstairs and down stairs rooms.


Use a plumbing camera with detector. The camera head puts out a very localized signal. Plus, you can view the camera output to find dead-ends.


If you know the rough location of the outlet take a 4' level and run along the drywall horizontal and you'll see a hump in the wall....this should be the outlet location.

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