Using swimming pools as heat sinks for air conditioner waste heat has been estimated to reduce air conditioner energy use in California by 25-30% (Harrington and Modera 2013). There are two primary advantages of rejecting waste heat to an air conditioner instead of ambient air: 1) swimming pool temperatures are typically colder than ambient air during peak cooling periods, and 2) water is a superior heat transfer medium than air resulting in better heat exchanger performance. These both result in lowering compressor head pressures and associated energy use. This process also has the added benefit of providing “free” pool heating which would increase the benefits to consumers and spur market adoption. This paper describes the results from a demonstration of a retrofit technology for allowing air conditioner waste heat to be rejected to a swimming pool. The technology allows a maximum pool temperature to be set by the user, and switches between the existing air-source condenser and the water-source condenser depending on the heating needs of the pool. The performance of the existing air-source condenser was monitored for a period of three months. Subsequently the air conditioner was retrofitted with the pool-source condenser and monitoring continued for another 6 weeks. The results showed that the air conditioning energy use was reduced by 12% when attributing the pumping power used for the process toward standard pool filtering, and 6% when attributing all pool pumping energy to the air conditioner. The retrofit technology provided the largest benefit during hot conditions with a 31% improvement in the efficiency of the air conditioner when outdoor temperatures were above 35°C (95°F). In general, the air conditioner performance was much more consistent after the retrofit due to the relatively narrow range in pool temperature conditions across the monitoring period. This resulted in much more stable cooling capacity and power draw. There was also an impact on pool comfort with an estimated increase in pool temperature conditions of 1.3°C (2.3°F) during the monitoring period. These results would vary depending on the size of the pool relative to the air conditioner capacity the pool is absorbing heat from. A pool thermal model is required to make accurate predictions of performance in different applications.