The first downhole heat exchanger (DHE) in Klamath Falls, Oregon, perhaps the first in the world, was installed in 1931 by a local plumber, Charles B. “Charlie” Leib, as an experiment and as a favor to a friend. Charlie had worked as a plumber/pipe fitter in Pennsylvania, moved to Klamath Falls in 1928, and worked for a local plumbing shop. Much of his work was repairing pumps and piping, and cleaning out cast iron radiators in the geothermal systems then in use. They used the geothermal water directly in the systems at that time