Central Hot Water System with Primary and Temperature Maintenance Heat Pumps

Central heat pump water heaters (“CHPWH”) are now an ongoing offering of utility efficiency programs such as “WatterSaver” and technology and equipment for clean heating (“TECH”). Furthermore, CHPWH systems now have a prescriptive path for compliance in “Title 24”. However, there are still few fully assessed field installations, most of which have electric resistance swing tanks for temperature maintenance and slightly lower efficiency than predicted by rated conditions in Northwest Energy Efficiency Alliance’s (“NEEA”) qualified products list. Although separate temperature maintenance is often necessary, especially for carbon dioxide (“CO2”) heat pump models, field demonstrations have shown that the electric resistance swing tanks cause large energy efficiency (“EE”) penalties in these systems. Past studies have shown that electric resistance swing tanks can account for anywhere between 15 and 60 percent of the total system energy consumption. This greatly decreases overall system efficiency, often reducing coefficient of performance (“COP”) well below what should be possible. It also increases peak demand of the system since swing tanks are not typically locked out during peak hours. One (1) solution to this temperature maintenance efficiency bottleneck is to use a smaller, parallel integrated heat pump water heater (“HPWH”) instead. Replacing electric resistance swing tanks with a parallel, integrated HPWH could reduce peak demand by around 15 kilowatt (“kW”) and energy consumption by ten – thirty percent (roughly 15,000 kilowatt hours per year (“kWh/yr”) in a 100-unit apartment building, for example). This would improve return-on-investment, lower end-user operating cost burden, and enhance the total system benefit (“TSB”) and greenhouse gas (“GHG”) impacts of EE programs. End-users are the building owners who may or may not pass on the cost impacts to tenants.Parallel integrated HPWH temperature maintenance is a new configuration and requires validation, standardization, and design guidance. Thus, this project will assess the performance of this CHPWH configuration in a multifamily building context, produce engineering design guidance (or “design guide”) documents, and pave the path for inclusion of this high-efficiency configuration in manufacturer product lines, qualified products lists, and utility programs. Quantifying the benefits of this parallel HPWH temperature maintenance technology (or the “Technology”) and including them in design guides and qualified products lists as standard configurations would increase the return-on-investment by CHPWH utility programs. It would improve the measure class, enhance energy savings, reduce peak demand impacts of electrification, and lower energy cost burdens for end-users. Eventually, CHPWH configurations with parallel HPWH temperature maintenance may be appropriate for including in Title 24 sections for CHPWH systems. Modeling, evaluation, and standardized design guides are the necessary first steps towards that eventual goal.The “Project Plan” will be carried out by Alternative Energy Systems Consulting, Inc. (“AESC”) and its associated subcontractors, ASK Energy, Inc. (“ASK Energy”) and Ecotope, Inc. (“Ecotope”), who will collectively be referred to herein as the “Project Team”.