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Integrated Heat Pump Water Heaters

Field Test of Integrated Heat Pump Water Heaters

When integrated with heat pump technology, an efficient water heater can be two to three times more efficient than conventional, electric resistance water heaters. This project installed heat pump water heaters and metering equipment in 40 homes (treatment sites) and metering equipment in an additional 13 homes (control sites) throughout the Pacific Northwest. The purpose of this work is to monitor the homes for efficiency, performance, reliability, electric demand, application issues and customer behavior.

This field demonstration is part of a nationwide test of 160+ residential heat pump water heaters, led by Electric Power Research Institute (EPRI). Once this larger project is complete, EPRI will release a final report documenting the performance of heat pump water heaters.

Project Team
BPA: Kacie Bedney, Jack Callahan, Sarah F. Moore
Snohomish PUD: Natasha Houldson and Kevin Watier
EPRI: Ammi Amarnath

2009 - 2012


Laboratory Test of Integrated Heat Pump Water Heaters

With little cooling load and generally low to moderate temperatures, Northwest climates are not always ideal for heat pump water heaters. Comfortable, reliable energy savings are still possible through careful selection of equipment and location for installing the appliance. Many installations occur in unconditioned buffer spaces that experience cool temperatures much of the year. The compressor must function efficiently under these conditions to create to a sound case for investment.

Three models were thoroughly investigated through laboratory testing and modeling: AO Smith’s Voltex, GE’s GeoSpring, and Rheem’s EcoSense. These reports summarize research findings, identify factors of energy consumption, and estimate operating efficiency and typical annual electricity use in unheated buffer spaces and interior conditioned spaces throughout the Pacific Northwest.

The combined lab and modeling results suggest the determinants of efficient HPWH operation:

  • Resistance element runtime and operational strategies
  • Compressor characteristics including efficiency, operating range, and capacity
  • Tank storage volume relative to hot water load
  • Ambient air temperature surrounding the HPWH
Project Team
BPA: Kacie Bedney, Jack Callahan, Sarah Moore
Ecotope: Ben Larson, Michael Logsdon, David Baylon

National Renewable Energy Laboratory: Dane Christensen, Bethany Sparn, and Kate Hudon.

2009 - 2011


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