Ground-source heat exchangers can be installed in a variety of ways. The majority of installations are closed-loop that involves the installation of a sealed loop of piping through which a liquid solution is circulated to exchange heat (Figure 3). Some open-loop systems circulate water from a lake,pond, stream or well. Open-loop systems are limited due to the lack
of water and problems related to the pipe clogging. In either application,the piping is used to transfer the heat. For closed-loop systems,