Because GeoExchange heat pumps work on different principles and are contained indoors, they require little maintenance or attention compared to the normal furnace/air conditioning systems. Not being exposed to the elements, dirt, leaves or vandalism and with less moving parts makes them highly dependable. The underground components, when properly installed, are virtually worry free with warranties up to 50 years. Properly installed GeoExchange systems offer the highest indoor air quality available today. A study by the Environmental Protection Agency found that high efficiency GeoExchange systems are on the average 48% more efficient than the best gas furnace and more than 75% more efficient than oil furnaces. The best GeoExchange system even outperforms the best gas heat pumps by an average of 36% in the heating mode and 43% in the cooling mode, less gas costs.
GeoExchange has two types of energy sources, ground/ surface water or ground source systems. Ground water has a stable temperature (4 -10 C / 39 – 50 F) in most parts of the world. The ground/surface water heat source is tapped into by open or closed loops. Closed loops work with a direct expansion system. The working fluid evaporates in underground heat exchangers or brine loop systems. Open loop systems draw water from one source then discharge it back to the earth. Ground-source systems also have a constant temperature and are used for both residential and commercial applications. A series of pipes are laid vertically or horizontally in which the heat is extracted from the earth by either direct heat expansion or a brine system.