Heat Pumps first originated in the mid 1800’s and have come a long way since then. There are several different types but the two most common are air and hot water heat pumps. Water is most commonly used in a commercial or high rise residential building. In the heat pump unit there is a refrigeration compressor, two heat exchangers (one to the building loop and one passing air through it to cool/heat the air), a supply air fan, and a reserving valve. The unit is capable of cooling the supply air by discarding heat into the building loop, and vice versa - when the reserving valve changes the flow of refrigerant the unit is capable of heating the supply air by obtaining heat from the building loop. Therefore in the summer the heat pump loop warms up and is cooled via a cooling tower, and in the winter time the heat pump loop is cooled and warmed by boilers. Ground source heat pumps are the same as the system just described above but the heat pump loop is heated and cooled via the ground. Deep holes are drilled into the ground to extract heat or inject heat from the heat pump loop into the ground, as the ground temperature is always in around 55 0F (13 0C). Therefore no cooling tower or boilers are required to operate this system, making it a very energy efficient system and it a very environmentally sound system.