States that a water-loop heat pump system consists of individual water-source heat pumps located in each zone. The heat pumps are linked with a common circulating water loop that serves as a heat sink when cooling and a heat source when heating. When cooling dominates, the temperature of the water in the loop increases. When heating dominates, the temperature of the water in the loop decreases. Describes an examination of the operation of systems over a range of loop water temperatures and notes trends in performance characteristics. On the basis of the analysis develops recommendations for loop water temperatures that minimise system energy consumption.

KEYWORDS: Heat pumps, water heat pumps, heating, cooling, water temperature, optimum, energy consumption