Groundwater is usually supplied to the heat pump by a drilled well with a submersible pump system. If a recharge well is to be used, it should be drilled at the same time as the primary well. The groundwater should be tested for acidity, dissolved solids and mineral content.
After a well is drilled, a drawdown test pump is used to draw water from near the bottom of the well. This test is conducted for 24 hours at twice the operating flow of the heat pump to be installed.
The test results are then interpreted to determine the expected drawdown for use in sizing the well pump. This test also serves to clear the well bore of drilling debris and residue.
In operation, the water is used on a once-through basis and then must be disposed of in some acceptable manner.
Learn more about: Reinjection & Disposal
Lakes, ponds and other water sources
Since plastic pipe is buoyant even when filled, headers and service lines must be anchored in place. The loops, anchors and service lines should be assembled, leak checked and pressure tested on land.
The assembly should be filled with air, not water, and floated into place with the weights attached. When in the proper location, the system is filled with water and sunk into position.
Service lines must be buried from the structure, across the shore and out into the body of water. They may be secured to docks or piers at or near the bottom.
There have been a number of successful installations where copper, polyethylene or polybutylene pipe coils are set in lakes or ponds. If copper coils are used with plastic pipe headers, NEVER thread a plastic fitting into a threaded copper or brass fitting if it is to be buried. This type of connection will leak over time due to wide temperature swings.
Experience indicates that copper loops should be at least 150 feet, and plastic pipe should be 300 feet, per cooling ton of installed heat pump capacity. The coils should be installed either vertically or horizontally with provision to keep them above the bottom.