Geothermal water heaters, also called ground water heating, typically come as a package deal with your domestic geothermal cooling and heating. Domestic geothermal heating and cooling take advantage of the fact that a meter or two beneath your property, the earth's temperature remain constant year around. By running tubes into the earth, and circulating fluids through, warm temperatures can be brought into the home during the winter and cool temperatures can be brought in during the summer. For geothermal water heating, a fluid with a low boiling point is pumped into the ground, then heat exchanged with water to make it hot.
This type of system work best if you have a large lot with plenty of room to lay tubing. It is the least cost installation because the cost of digging a shallower hole is less. Trenches are typically no more than two meters (six feet). The closed loop system works by taking two tubes into the ground, one being cold water exhuast, the other being the hot water return from the ground. A simple pump in the home keeps the water flowing. The only external energy needed to keep the system working is to drive the water pump. The low power pump can be powered by a renewable energy source.
This type of geothermal heat pump is used for those with a small lot. To get the equivalent thermal mass in a small space, holes must be dug much deeper. Rather than diggin up huge chunks of land, small vertical holes are drill deep into the earth, sometimes as much as 130 meters (400 feet). A matrix of many holes are dug. the tubes burried in these holes is then connected by a two-way manifold. The entire system is still one circuit of tubing.
The same circuit principal as before, however, loops of tubing are laid at the bottom of a small lake or pond. The advantage here is that you don't need to dig a hole. However, the tubing must be laid at least three meters deep to avoid freezing in cold climates.
The method of geothermal heat pump takes advantage of the water table beneith your property by using two existing wells. One tube draws warm water out of one well. The other tube pumps water in to recharge the well.
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