How to Test a Geothermal Ground Loop

A geothermal ground loop is a component in a ground source heating and cooling system. Ground source systems use underground soil temperatures to regulate the temperature in buildings. The ground loop is a horizontal, closed loop of high density polyethylene -- or HDPE -- pipe buried 6 to 8 feet underground. Water and antifreeze circulate through the pipe, which is attached to a compressor. The compressor extracts heat from the circulating fluid in cold weather and the “exchanged” heat is used to warm buildings equipped with these systems. In the summer, the same systems can be used to cool the buildings.

Mixture of water and antifreeze
Backhoe and shovels
Hydrostatic pressure tester
ASTM F2164 – 10

Instructions

- 1
  Examine all connections, joints and mechanical seals for obvious defects. Solvent-cemented pipes must be fully cured before testing.
- 2
  Fill the ground loop with the mixture of water and antifreeze specified in the plans for the ground loop.
- 3
  Shallow backfill the excavation containing the ground loop while leaving all joints exposed, using a backhoe and shovels. Shallow backfilling minimizes the expansion and contraction of the ground loop.
- 4
  Connect a portable, hydrostatic pressure tester to the compressor end of the ground loop, using either the thermal or mechanical connections specified by your ground loop’s design and the pressure tester. Hydrostatic pressure testers include an air compressor and pressure gauges.
- 5
  Pressure test the ground loop using the standard “ASTM F2164 – 10.”
- 6
  Low pressure test the ground loop at normal operating pressures, long enough to find very small leaks by visual inspection. Low pressure tests typically last about 1 hour.
- 7
  High pressure test the ground loop at 150 percent of normal operating pressure for 12 hours, using the hydrostatic pressure tester. Monitor pressure levels throughout the entire high pressure test. Find leaks by visual inspection, if hydrostatic pressure levels suddenly drop during high pressure testing, and discontinue high pressure testing if leaks are found.
- 8
  Replace any pipe sections that fail during high pressure testing, and repeat both low and high pressure testing.
- 9
  Disconnect the pressure tester, and completely backfill ground loop excavations that successfully complete 12 hours of high pressure testing. Backfill excavations with a backhoe.

How Do I Build a Four-Sided Cupola?

How to Install Xtru-Coat Piping

Exterior Remodeling