Demonstration and Assessment of Residential Gas Heat Pump Water Heaters in the Los Angeles Basin

This project included the demonstration, measurement, and verification of a gas heat pump water heater prototype in five single-family homes in the Los Angeles Basin. Developing a simulation model helped assess the energy, emissions, and cost savings of this technology compared to other commercially available water heating options across the 16 California climate zones. Laboratory-based extended life and reliability testing was performed to assess the market opportunities and barriers to introducing this new technology. The researchers undertook outreach to stakeholders such as utilities, plumbing heating, ventilation, and air conditioning, and home energy improvement contractors, consumers, manufacturers, and other researchers to facilitate knowledge and technology transfer through presentations, papers, and online workshops.

The project included commissioning and shipping six precommercial gas heat pump water heater units to California and installing at five home sites and a research laboratory. After testing for more than three months, average annual savings were 110 therms or 54 percent compared to baseline using with CO2 emissions reductions of 49 percent. Individual site savings ranged from 23 percent to 67 percent, from varied consumption and baseline equipment. The technology developer Stone Mountain Technologies is conducting additional demonstrations outside California and plans to have a series of different models be in commercial production starting in 2023 to early 2024. The company was able to raise an additional $15 million in new investment.