The operation of water-to-air heat pumps using lakewater as the heat source and sink has been investigated. Operation of direct cooling with deep lakewater has also been investigated. Although the emphasis of the work was with southern lakes, many results also apply to colder climates. During the project, several open-loop systems - one closed-loop plastic coil system and one copper coil system - were monitored. Many thermal surveys of lakes were located and performed. Computer codes were developed to determine closed-loop coil length and lake thermal response to assist in design guideline development. This paper also includes recommendations concerning heat pump selection, pumping systems, piping arrangements, and lake size/depth characteristics.

KEYWORDS: lakes, heat pumps, water heat pumps, water air heat pumps, USA, designing, feasibility, selecting, pipes.