pressure testing a geo loop

zepfan

What is the best way to pressure test a geothermal ground loop? We have a job with five water source heat pumps, served by two ground loops, 1.5" pvc. One loop when it was running fine over the summer had 5 psi with the pump off, and the other had 35 psi. The other day one loop had 0 psi and the three units connected to it were off on freeze protection. I opened the 1" plug on the side of the flow center and did not get one drip of fluid. The homeowner just had both loops re flushed and filled by a well company last summer. When contacted the well company said that the loop should be hydro tested and may just have air pockets. I would have thought that the loop would have been tested before it was refilled, and do not see how this could just be air pockets. I was planning on putting a tee with gauge and hose bib on one side of the flow center, and a hose bib on the other 1" port in the flow center, isolate the loop from the units, and fill it with water to 10 psi, and see if it holds. My concern in doing this with water is that if there is not a leak the water could freeze in the loop, even though almost all piping is below grade then goes through a conditioned area. If there is a better way to go about this, I would be up for suggestions. Thanks to all

Jamie Hall

Is there an expansion tank anywhere on the system which can be connected to the loop you want to test? Or could you get one and hook it in somewhere on the loop? If so, by far the best approach is going to be to use that expansion tank and a controlled fill to get a specific static pressure in the system, then run the pump to keep things from freezing. Then from time to time stop the pump and see what your static pressure is.

EBEBRATT-Ed

Is it glycol? You could test it with air but when you release the air it will push water out.

pecmsg

Why?

pump it up on one side only slowly. 10-15 PSIG and let it sit 24-40 hrs. Slowly release the air IF it passes. 

hot_rod

PVC loops? Usually they are PE or PP. You cannot use glycol in PVC, according o Dow. Perhaps some GEO fluids like ethanol or methanol based.

Use an air test, 60 psi maybe.

It would take a 1-1/2 hp or larger purge cart to blast out loops 1" or larger.

zepfan

thanks to all that responded. No there is not an expansion tank on the system and the fluid that was originally used was ethanol, not glycol