PG&E and SCE HPWH Laboratory Testing and Software Updates for Multifamily Applications

Unlike the single-family residential market where a one-size-fits-most approach to HPWH systems is feasible, multifamily water heating systems require more varied designs targeted at specific building types and sizes. Design possibilities are myriad, beyond mere equipment selection, but many designs either do not provide adequate hot water or use too much energy or both. In fact, this research shows that system configuration determines the ultimate energy use as much as, if not more so, than the heat pump itself. Factors include different temperature-maintenance system configuration, sizing of primary and secondary storage tanks, piping configuration for recirculated water, range of distribution system losses, and storage water temperatures. If HPWH systems are configured and sized like traditional gas boiler systems, buildings will be left with functional issues and poor performance. This project’s goal was to research, understand, and demonstrate good central HPWH system design so that efficiency and energy savings can be achieved.