Demonstration of “Combi” Air-To-Water Heat Pump

Air-to-water heat pumps (AWHPS) have been gaining traction worldwide in countries where hydronic heating is the predominant HVAC option., With the United States increasing national focus on decarbonization of the building sector, the AWHPs market still trails behind other more popular HVAC options. AWHPs provides year-round space conditioning, and in several AWHPs also provide dedicated domestic water heating. This "three function" (i.e., space heating, space cooling, and domestic water heating) combination operation is attractive as a cost-compression technology. The “three function” not only allows for the unit's high-capacity compressor to be used to satisfy water heating loads but also simplifies installation, avoids costs associated with space constraints, and simplifies electrical service requirements. A supplemental factor that may support the decarbonization of the building section is the recent developments in AWHPs and inverter compressors (I.e., variable speed). This development allows for the utilization of low global warming potential (GWP) refrigerants (GWP >750) and operates at heating Coefficient of Performance (COPs) of 3-5 in California climate. This will additionally reduce operating costs, upfront costs, and electric demand load compared to other state-of-the-art high-efficiency technology.   The performance of AWHPs in "three-function" mode is strongly variable during the heating and cooling. Currently, there is a lack of rating standards for computing the seasonal performance of AWHPs in North America, especially for "three function" operations. The current Methods of Test (MOT) and rating standards (i.e., AHRI 550/590 and ASHRAE Standard 206) are not representative of the performance of the current state-of-the-art variable speed (i.e., inverter) AWHPs performance with hydronic emitters in the field. Therefore, detailed field, laboratory, and modeling evaluations are required to highlight the benefits of AWHPs for the U.S. market to support the development of work papers and future incentives.  In this project, GTI Energy will conduct two field evaluation to validate the performance of the high-efficiency and low-GWP state-of-the-art AWHPs technology in the California single-family home residential market to support the development of workpaper or Technical Reference Manual (TRM) to accelerate the path to market for AWHPs.