Gas-Fired Absorption Heat Pump: Hybrid System Approach Field Study

Stone Mountain Technologies Inc. (SMTI) has developed a residential-sized gas-fired absorption heat pump designed for broad residential and commercial applications. These prototype systems were tested in the Chicago region at one multifamily building and two single-family homes, either replacing or supplementing existing natural gas heating equipment. The multifamily demonstration, supported by a boiler manufacturer and SMTI, required extensive installation design and controls development, which led to several improvements in the product’s design and system performance. Field data showed the hybrid system could achieve net efficiencies of up to 136%, with gas savings of 54% in hot water-only mode and up to 55% in combined heating modes at the multifamily site. At the residential sites, the system achieved net efficiencies between 110% and 130% in combined heating modes. 

These findings support NEEA’s understanding of how hybrid gas-fired absorption heat pump systems perform in real world conditions. They provide insights into the systems’ durability and energy savings potential and help inform NEEA’s ongoing efforts to identify and advance high-efficiency technologies that benefit Northwest consumers.