Report Number




Water Heating; Buildings


The Hot Water System (HWS) Laboratory test facility at the Florida Solar Energy Center (FSEC) in Cocoa, FL was used for testing seven differing types of residential water heating systems. The HWS building provides unconditioned housing (similar to a garage in Florida) for one reference electric 50-gallon heater, three solar thermal electric assisted systems, one electric tankless system, one reference 40-gallon natural gas (NG) and tankless gas system. The performance of all seven systems has been compared in a side-by-side test configuration over a full year period. Simultaneous hot water draws take place for all hot water heating systems on a daily basis at the HWS facility, with evaluation of two draw profiles. The ASHRAE 90.2 profile calls for draws at the beginning of every hour with a total hot usage of 64.3 gallons per day (gpd). The second draw profile, created with the National Renewable Energy Laboratory (NREL) and under the Building America (BA) program was formulated to simulate realistic family hot water draw patterns. This draw profile is seasonally adjusted (42 - 67 gpd) to account for inlet water temperature variations and feature more realistic draw patterns (e.g. multiple draws during the hour). Efficiency results were measured and analyzed as draw pattern dependent subjects. Average daily electric use for each system was determined as well as average and peak day electric demand.

Date Published


Local Subjects

Buildings; Water Heating


FSEC Energy Research Center® Collection



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