ICF - Lincus Gas-Fired Heat Pump Water Heating & Combination System 2025

This study aimed to evaluate the performance, energy efficiency, and carbon emissions reduction potential of gas absorption heat pump water heaters (GAHPs) in real-world applications, focusing on addressing barriers to adoption. Conducted under Phase 2F of a pilot study within the Gas Emerging Technologies (GET) Program, the research was implemented at a multifamily housing site in Rowland Heights, California. The project sought to provide critical data on GAHP operation in domestic hot water (DHW) systems, filling gaps in understanding related to performance, maintenance, costs, reliability and compatibility with existing infrastructure. While the results were promising, follow-up work is recommended to improve the GAHP system integration performance.

The GAHP employs an ammonia-water absorption cycle to extract heat from ambient air, achieving thermal efficiencies above 100%. Compared to baseline systems reliant on gas-fired boilers, the GAHP demonstrated marked performance improvements. The post-installation system achieved an average coefficient performance (COP) of 0.70, representing a 12% increase from the initial baseline COP of 0.63 and a 5% increase from the re-baseline COP of 0.67. The re-baseline efficiency increase was due to boiler #2 being replaced with a new one midway through the post-installation period. The GAHP’s performance was affected by shorter runtimes, averaging 17.9 minutes per cycle, which prevented the system from achieving its optimal COP of 1.1 or higher. Annual gas savings were calculated at 2,158 therms, translating to an 8.5% reduction in gas consumption.