Ground Loop Configuration
The copper tubing consists of a line set, a pair of manifolds, and several earth loops. The line set is the pair of main copper pipes coming from the heat pump compressor unit, usually located indoors. One line is for the liquid refrigerant, the other is for gaseous refrigerant. The line set runs through the building wall and runs underground to the location of the manifolds. Each manifold (one for gas and one for liquid) serves to allow a main pipe to be attached to the earth loops which exchange heat with the ground.
The earth loops can be installed vertically, diagonally or horzontally 6 foot (1.8 m) deep and laying the earth loops on the bottom of the pit before installation is done by drilling several boreholes radiating outward from the manifolds and placing an earth loop into each of the boreholes. After the earth taps are placed, the boreholes are then filled with grout for good thermal contact between loop and soil.
The boreholes are drilled to a length of 50, 75 or 100 ft (15, 22 or 30 m) with a diameter of 3 inches (76 mm). A total of 100 feet (30 m) to 140 feet (43 m) of drilling is needed for each ton (3.5 kWth) of system capacity.
Because copper is a naturally occurring metal that survives in the ground for thousands of years in most soil conditions, the copper loops have a very long lifetime in most soil conditions. Corrosion of the copper earth loop in acidic soil can be eliminated through installation of a sacrificial anode.
Read more about this topic: Direct Exchange Geothermal Heat Pump
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