Feasibility of Municipal Water Mains as Heat Sink for Residential Air-Conditioning

Abstract

It has been proposed that municipal water mains be used as the heat sink or the heat source for air-conditioning or heating, respectively. This paper addresses the extent of thermal contamination associated with the use of municipal water in the mains for heat rejection in residential air-conditioning applications. A small residential neighborhood in Austin, Texas was selected, and typical residential a/c loads and measured water supply rates in the main were used in the assessment. Very substantial increases in water temperature occur in the mains for air-conditioning, even if a modest fraction of the residents opt to install such systems. No more than 1 to 2 % of residents could adopt such systems before water temperature rises in the mains become significant. The general conclusion is that, while the benefit to an individual using this concept may be positive, the impact on water temperature is excessive.