What is the definition of a water loop heat pump? A water loop heat pump is a type of heat pump that uses a water loop to transfer thermal energy from one location to another. This type of heat pump is most commonly used to heat and cool large buildings, such as office complexes, shopping malls, and apartment buildings. This type of heat pump utilizes an evaporator coil, which is filled with a refrigerant, to absorb heat from the air or ground. The refrigerant is then circulated through a closed water loop, transferring the thermal energy to the condenser coil. From there, the heat is released into the building, cooling or heating the indoor environment. The water loop is also used to transfer the condenser coils’ heat to a cooling tower or geothermal loop, where it is released outside. This type of heat pump is an efficient and cost effective way to heat and cool large spaces.