Loop for cheap-and-cheerful system: step 2, actually testing

Discussion in 'Vertical and Horizontal Loops' started by norwood, Apr 12, 2021.

  1. norwood

    norwood New Member

    Hello again!

    OK, time for another question about our cheap-and-cheerful attempt to turn a 3 season greenhouse into a 4 season greenhouse, with the help of a 500 foot PE-RT loop.

    We haven't bought a GSHP for it yet, because I'd really like to test the loop first. As waterpirate suggested in my original thread (https://www.geoexchange.org/forum/t...ul-system-step-1-how-to-test.8233/#post-67749) we did indeed clamp a barbed adapter to each end of the PE-RT. I then attached one "100 PSI Air/Gas Test Gauge" (from PEX Superstore) to each end and pressurized the loop via the air chuck on one of them, to 50psi.

    Here's what the setup looked like: (please pardon my lack of photography skills)


    That was Saturday evening. This morning, we were at 10psi. Hmm. Wondering how much of that was the pipe stretching, I pressurized it to 54psi this morning - but by evening, it was at around 30psi.

    I realize that these systems are meant to be tested with water, not air, and I also realize that the chance of my having a leak in a system with no junctions should presumably be very low. I had tried to be careful about putting soft dirt (not rock) on the loop while refilling it. There had been one area that kinked, but I did straighten it out immediately; the next morning I looked at it and couldn't even tell where it had been kinked. I was still worried about it, so I called Oil Creek Plastics (who made the PE-RT) and spoke with an engineer there. He said it would probably be OK, but should perhaps be run at a little lower pressure - say 50psi.

    What do you think? Did I do more damage with that kink than I'd thought? Or is my connection between the loop and the test gauge maybe not as tight as I thought it was? Or is air just so useless for testing loops that there's no point in trying to interpret these results?

    Thanks in advance!
  2. SShaw

    SShaw Active Member Forum Leader

    Air is not useless for testing. My ~4,500 feet of HDPE ground loop was tested using air. It was charged up to about 100 PSI and stayed there for days.

    Drastic temperature changes can affect the pressure, but it sounds like you have a leak somewhere. I'd start with a soapy water test on all the fittings near the gauge.
    gsmith22 likes this.
  3. norwood

    norwood New Member

    A leak it was -- but not, praise God, in the loop. It turned out to be the white PTFE tape that I'd mistakenly thought would seal the threads. Removing the test gauges, cleaning off the remnants of the PTFE tape, applying pipe dope, and tightening it all back up made a huge difference. I pressurized the loop to 50psi on Saturday afternoon, and it was at 46psi today, with the ambient temp having also fallen considerably.

    Does this qualify as tight enough that I don't need to worry about a non-pressurized flow center? Or is that something I should still be considering, just because I'm doing it myself and have (as I'm demonstrating, I suppose) very limited experience with this?
    waterpirate likes this.
  4. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    IMHO non pressurised is the only way to go for diy. It allows for a lot of not perfect things, while still circulating the fluid and keeping the system running with no fault codes to de cipher.

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