As a natural phenomenon, just as water flows from low to high, the heat also always flows from high to low temperature. But people can create machines that use water pumps to pump heat from low to high temperatures, just as water is raised from low to high. Therefore, the heat pump is essentially a heat lifting device, which itself consumes a part of the energy, excavates the stored energy in the environmental medium and increases the use of the temperature. The heat pump consumes only a third of the heat One or lower, which is also the energy-saving features of the heat pump. Heat pump is the need for the heat of the condenser, the evaporator heat from the environment, this time from the environment to heat the object is called the heat; the opposite is the need to cool the evaporator, the condenser heat to the environment, this time The object of environmental heat release is called cold source. Evaporator condenser according to the circulating refrigerant and the environment of the heat transfer medium is divided into two main forms of air heat exchange and water heat exchange. This heat pump or refrigerator according to the environment and the heat transfer medium can be divided into water - water, water - air, air - water, and air - air four categories. The use of air as a heat source heat pump, called the air source heat pump. Air source heat pump has a long history, and its installation and use are very convenient, widely used. However, due to the difference of regional air temperature, the typical application in our country is south of the Yangtze River. In North China, average winter temperatures are below zero degrees Celsius. Air-source heat pumps are not only run in poor conditions, poor stability, but also inefficient because of frost formation. The use of water as a heat source heat pump, called water source heat pump. Water is an excellent heat source. Its heat capacity is large and its heat transfer performance is good. Generally, the efficiency and capacity of cooling and heating of water source heat pump are higher than that of air source heat pump. However, the application of water source heat pump is much less than that of air source heat pump due to the limitation of water source. Ground source heat pump is a form of water source heat pump, it is the use of water and ground energy (groundwater, soil or surface water) for cold and heat exchange as a source of heat and cold water source heat pump in winter to heat "Come out to supply indoor heating, at this time can be a" heat source "; summer to remove indoor heat, released into the groundwater, soil or surface water, at this time can be" cold source. " Ground source heat pump heating air conditioning system is divided into three parts: outdoor heat exchange system, water source heat pump units and indoor heating air conditioning terminal system. Water source heat pump which there are two main forms: water - water or water - air type. Heat transfer between the three systems * water or air heat exchange medium, heat exchange medium between water source heat pump and ground energy is water, and heat exchange medium of building heating and air conditioning end can be water or air.