Six 5th generation prototype gas heat pump water heaters were recently commissioned. Five were installed in homes in Southern California while the sixth was sent to a test lab for further evaluation. The units were installed in June of 2018 and will continue operation for 1 year. Prior to installation, one of the prototypes was 3rd-party tested for NOx emissions, and easily passed the current SCAQMD regulation for residential water heaters. This project will help further develop the prototypes reliability and is a crucial step before starting production. The prototypes are fully instrumented by a 3rd party to measure energy use. Baseline testing was performed with the original water heaters to help determine total energy and cost savings provided by the heat pump water heaters to the end users.