Today, Klamath Falls, Oregon, has several hundred hot water wells in use, primarily for the purpose of heating homes. This method of heating residences has been in use in the eastern portion of Klamath Falls for more than forty years. Typical plumbing in these hot water wells today consists of a closed loop of 2-inch black iron pipe suspended in the well and fitted with city water. The portion of the loop which is submerged in hot water constitutes the downhole heat exchanger and the heated water is circulated by natural convection. Hot water is lighter in weight than cold water and, therefore, rises in the hairpin loop while the heavier cold water descends, thereby causing natural flow within the loop. A small electric pump is sometimes used to aid this natural flow