The downhole heat exchanger (DHE), used extensively in Klamath Falls in over 500 installations, provides heating for one or more homes from a single geothermal well. The DHE eliminates the problem of disposal for geothermal fluids, since only heat is taken from the well. The heat exchangers consists of a loop of pipe or tubes (locally called a coil) suspended in the geothermal well through which “clean” secondary city water is pumped or allowed to circulate by natural convection. These systems offer substantial economic savings over surface heat exchangers where a single-well system is adequate