Since 1980 about 200 apartment buildings including condominiums, with over 25,000 apartment units, and about 15 hotels in Hawaii have replaced their conventional central service water-heating systems with central heat pump water-heating systems. Both air-to-water and water-to-water heat pumps are utilized with electrically driven reciprocating or centrifugal compressors. To verify the actual performance of these commercial heat pump water-heating systems, the electric utility serving the City and County of Honolulu compiled before-and-after performance data on over 20 installations. Recorders were installed on eight of these heat pump systems' submeters and their building service meters to obtain their energy-use profiles. The former fuel-fired water heaters used between three and nine times as much energy as the heat pumps and the savings provided reasonable payback for the heat pump first costs. Typical electrical demand profiles for both the water heating systems and the buildings are included.

Units: Dual