A water-to-air geothermal heat pump, device at the heart of a geothermal system, is designed to extract heat from a low-grade source (like the earth) by way of an open or closed loop and concentrate it for use to heat a space. It consists of a compressor, a blower motor and a circulating pump. A reversing valve enables it to switch functions to provide both forced air conditioning and heat to a home using  it's blower motor.