Pond-Coupled Closed Loop Geothermal Systems
Ponds with at least 10 feet deep water and a minimum half acre surface area make an excellent choice for a closed loop application. A pre-assembled heat exchanger made of polyethlyene plastic pipe is floated onto the surface of the pond, connected with an extended header, filled with a loop solution and submerged. Pond-coupled systems can reduce excavation costs and provide a lower installation cost than other closed loop (horizontal or vertical ) system options.
Geothermal heating and cooling systems use the natural and nearly constant temperature of the earth to heat in the winter and cool in the summer. This is accomplished with a compressor or heat pump unit, the liquid heat exchanger medium, and the air delivery system.
Geothermal systems quite simply extract heat from the ground or ground water and transfer that heat to a refrigerant, then distribute the heat into the structure with a forced-air or hydronic system. In cooling, geothermal systems take heat from the structure, transfer the heat to the refrigerant, then transfer the heat back to the water or loop fluid. This works the same as a standard air conditioner, except a geothermal system uses water or loop fluid at a constant temperature (average 50 degrees) instead of varying outdoor air.
Closed loop geothermal systems utilize a series of piping buried in the ground or submerged in a pond to create a heat exchanger. This piping is filled with a water/antifreeze solution (loop solution) that allows the geothermal system to take advantage of the constant temperatures stored in the earth or pond. There are several types of systems. Horizontal, Pond & Vertical.
The loop solution which circulates in the closed piping system absorbs heat or rejects heat into the surrounding earth or water. Closed loops can be installed into ponds, excavated and buried in the ground in a horizontal configuration using a backhoe, or drilled vertically with drill rig. Closed loops are virtually maintenance free, recirculating the same loop solution, and having no need for a well or drain to discharge the water. Due to the excavation and loop piping material costs, closed loops systems are generally more expensive to install than open loop systems.