This paper explores the laboratory performance of five integrated Heat Pump Water Heaters (HPWHs) across a wide range of operating conditions representative of US climate regions. Laboratory results demonstrate the efficiency of this technology under most of the conditions tested and show that differences in control schemes and design features impact the performance of the individual units. These results were used to understand current model limitations, and then to bracket the energy savings potential for HPWH technology in various US climate regions. Simulation results show that HPWHs are expected to provide significant energy savings in many climate zones when compared to other types of water heaters (up to 64%, including impact on HVAC systems).
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This paper explores the laboratory performance of five integrated Heat Pump Water Heaters (HPWHs) across a wide range of operating conditions representative of US climate regions. HPWHs are expected to provide significant energy savings in certain climate zones when compared to typical electric resistance water heaters. Results show that this technology is a viable option in most climates, but differences in control schemes and design features impact the performance of the units tested. Tests were conducted to map heat pump performance across the operating range and to determine the logic used to control the heat pump and the backup electric heaters. Other tests performed include two unique draw profile tests, reduced air flow performance tests and the standard DOE rating tests. The results from all these tests are presented here for all five units tested. The results of these tests will be used to improve the EnergyPlus heat pump water heater for use in BEopt(tm) whole-house building simulations.
Although heat pump water heaters (HPWHs) have gained significant attention in recent years as a high efficiency electric water heating solution for single family homes, central HPWHs for commercial or multi-family applications are not as well documented in terms of measured performance and cost effectiveness. To evaluate this technology, the Alliance for Residential Building Innovation team monitored the performance of a 10.5 ton central HPWH installed on a student apartment building at the West Village Zero Net Energy Community in Davis, California. Monitoring data collected over a 16 month period were then used to validate a TRNSYS simulation model. The TRNSYS model was then used to project performance in different climates using local electric rates. Results of the study indicate that after some initial commissioning issues, the HPWH operated reliably with an annual average efficiency of 2.12 (Coefficient of Performance). The observed efficiency was lower than the unit's rated efficiency, primarily due to the fact that the system rarely operated under steady-state conditions. Changes in the system configuration, storage tank sizing, and control settings would likely improve the observed field efficiency. Modeling results suggest significant energy savings relative to electric storage water heating systems (typical annual efficiencies around 0.90) providing for typical simple paybacks of six to ten years without any incentives. The economics versus gas water heating are currently much more challenging given the current low natural gas prices in much of the country. Increased market size for this technology would benefit cost effectiveness and spur greater technology innovation.
This paper explores the laboratory performance of five integrated Heat Pump Water Heaters (HPWHs) across a wide range of operating conditions representative of US climate regions. HPWHs are expected to provide significant energy savings in certain climate zones when compared to typical electric resistance water heaters. Results show that this technology is a viable option in most climates, but differences in control schemes and design features impact the performance of the units tested. Tests were conducted to map heat pump performance across the operating range and to determine the logic used to control the heat pump and the backup electric heaters. Other tests performed include two unique draw profile tests, reduced air flow performance tests and the standard DOE rating tests. The results from all these tests are presented here for all five units tested. The results of these tests will be used to improve the EnergyPlus heat pump water heater for use in BEopt(tm) whole-house building simulations.
The report describes laboratory testing and modeling exercises performed to assess potential heat pump water heater (HPWH) energy savings in the Pacific Northwest. Three integrated HPWH models, pairing two electric resistance elements with a tank-mound heat pump, were thoroughly investigated: the AO Smith Voltex, the GE GeoSpring, and the Rheem EcoSense. The report summarizes lab findings, describes the determinants of consumption, and develops annual operating efficiency and energy savings estimates for HPWH installations in unheated buffer spaces and interior conditioned spaces throughout the Northwest.
This presentation summarizes NREL's development of a HPWH model for use in hourly building energy simulation programs, such as BEopt; this presentation was given at the Building America Stakeholder meeting on March 1, 2012, in Austin, Texas.
"The Northwest Energy Efficiency Alliance (NEEA) contracted with Ecotope, Inc. and Cascade Engineering Services, Inc. to conduct a laboratory assessment of the GE model #GEH50DFEJSRA heat pump water heater (HPWH) for northern climate installations. Cascade Engineering evaluated the GEH50DFEJSRA using a testing plan developed by Ecotope to assess HPWH performance."--Executive summary.
