US Patent 8011032 Energy efficient circulation system for spas and hot tubs

A method and apparatus for circulating water in a bathing installation with a water circulation flow path and a tub for holding bathing water is described. A pump is submerged in a chamber in the circulation flow path so that the pump when operated provides a positive pump pressure to pump water through the circulation flow path from an inlet opening to an outlet opening. Thermal contact is provided between a pump housing surface and water in the chamber to allow heat transfer between the pump housing surface and water in the chamber.