This paper presents final results of a field evaluation of residential heat pump water heaters. This heavily instrumented field study was conducted in 17 homes across the United States over a period of 18 months. This study was unique in that the heat pump water heaters could be operated as electric resistance water heaters or as designed, heat pump water heaters with resistance backup. Field measurements of hot water usage, energy consumption, temperatures, and condensate generation provided ample data to assess the performance and efficiency of the heat pump water heater in a range of settings. The paper presents comparative results on energy efficiency, dehumidification performance, electric demand, and load factor impacts important to utilities as well as measured customer impacts in a switchover from electric resistance water heaters to heat pump water heaters.

Units: I-P