Experiments were conducted to evaluate a multipurposeheat pump, Daikin Althermal^TM split system, for its operationto provide space heating and domestic hot-water draw(DHW).The system was installed in the laboratory under controlledtest conditions with all default settings specified in the manufacturer'smanual.The system was first tested as a storage-typeheat pump water heater according to the procedure establishedby the U.S. Department of Energy (DOE). Tests forcombined space heating and domestic hot water were alsoconducted to simulate as-installed 24-hour heating demandsof a single-family house in Chicago, IL, Atlanta, GA, andHouston, TX, representing cold, mixed and warm climates inU.S. The results show that the energy efficiency of the testedsystem were extremely low (energy factor [EF] = 0.47) whenused solely for DHW heating. The average hourly system efficienciesfor combined space and water heating tests were 1.54,1.69, and 1.15 for Chicago, Atlanta, and Houston, respectively.The operating conditions and the appropriate applicationof this system are also discussed in this paper.