Geothermal
According to the U.S Environmental Protection Agency (EPA) geothermal systems are, "the most energy efficient, environmentally clean, and cost-effective space conditioning systems available today. Geothermal transfers heat from your home to the earth in the cooling mode, or from the earth to your home in the heating mode. There are four loop systems; open, closed, vertical and pond loop.
Open Loop System
Open-loop system (heat pump system) uses groundwater from a conventional well as a heat source in winter and a heat sink in the summer. The groundwater is pumped through the heat pump where heat is extracted (in winter) or rejected (in summer), then the water is disposed of in an appropriate manner. Since groundwater is a relatively constant temperature year-round, it is an excellent heat source /heat sink.
Closed Loop System
Closed-loop system uses a continuous loop of special buried plastic pipe as a heat exchanger. The pipe is connected to the indoor heat pump to form a sealed, underground loop through which water or an anti-freeze solution is circulated. Unlike an open-loop system that consumes water from a well, a closed-loop system recirculates its heat transferring solution in pressurized pipe.
Vertical Closed Loop System
Closed-loop systems can also be vertical. Holes are bored to about 150- 300 feet per ton of heat pump capacity. U-shaped loops of pipe are inserted in the holes. The holes are then back-filled with a sealing solution called grout.
Pond Closed Loop System
Closed-loop system can be installed in a nearby pond if it's deep enough and large enough. A minimum of 8-10 feet in depth at its lowest level during the year is needed for a pond to be considered. In the pond loops, polyethylene pipe must be used. Generally, a minimum of 1/2 acre pond is required to provide adequate surface area to heat transfer.
