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ACKNOWLEDGMENTS The following list of people contributed to the testing project and the production of this report: • Sherry Hu – Senior Program Manager, Emerging Technologies • KC Spivey – Supervisor, Emerging Technologies • Robert Davis – Senior Mechanical Engineer, Applied Technology Services • Al Beliso – Technologist, Applied Technology Services • Esteban Rodriguez – Senior Engineering Technician, Applied Technology Services 491-09.17.doc vi
INTRODUCTION Background While the majority of residential water heating in PG&E’s service territory uses natural gas combustion, there are some areas where gas service is unavailable or there may be no provision for exhaust venting from the building, and thus electricity is used for water heating. While they use a more expensive energy source, electric resistance water heaters tend to be very efficient from a site energy perspective, with Energy Factors ranging from 0.90 to 0.98. The high efficiency comes from the resistive heating elements transferring 100% of the electrical energy into the water (with no combustion or stack losses like fired units), and from a high level of insulation, including the bottom of the tank (which cannot be done with most bottom-fired gas systems). Because the range of Energy Factor for electric water heaters is narrow and because of their higher cost of operation, no conventional electric resistance heater has been considered under the recently introduced EnergyStar program for water heaters. The use of heat pumps to heat water has been looked at as a way to get more efficiency into electric water heaters as far back as the 1950s. They experienced a resurgence of interest during the energy crisis of the 1970s, but while these models showed some promise, they suffered from reliability problems and high cost, and few products survived to become installed on a large scale. Because of the reliability problems, most of these early products and the interest in them faded away in time. With the recent national emphasis on energy efficiency, and with significant improvements in refrigeration system components, heat pump water heaters (HPWHs) have received renewed interest, with new consumer products being introduced to the residential markets from several major manufacturers. The only electric water heaters to receive EnergyStar designation are heat pump systems. Because of this recent introduction and the low number of available consumer products, little is known about the operation and performance of heat pump water heaters or their potential for energy savings relative to other types of water heaters. In order to compare various types of water heaters, the PG&E Emerging Technologies (ET) program contracted with PG&E Applied Technology Services (ATS) in 2008 to develop a water heater test laboratory at the San Ramon Technology Center. By simulating realworld conditions, the test facility can evaluate the actual energy savings potential of hot water heaters beyond what is available from the available ratings. The objective of the water heater testing program is to enhance PG&E’s Mass Market program by providing supporting data for fact sheets and to provide data for cost effectiveness calculations to help determine appropriate incentives. The purpose of the study described in this report was to assess two types of HPWHs through laboratory testing, and provide energy performance data to the Emerging Technologies program. The scope of work included conducting laboratory testing to quantify the energy performance of these products, and evaluate the general functionality of the systems as consumer products. Prior Research This is the second laboratory testing project regarding residential water heaters conducted within PG&E. This project builds upon the 2008 PG&E Emerging Technologies gas water heater evaluation, described in Reference 2. Some initial investigation was made into the testing standards for HPWHs, including international standards as well as DOE and ASHRAE Standards. Objectives The objective of this project was to evaluate the operating characteristics of two new HPWH products, and to determine the performance parameters commonly used for rating water heaters. The performance parameters include: • First Hour Rating • Recovery Efficiency 491-09.17.doc 7
Page 1 and 2: Laboratory Testing of Residential H
Page 3 and 4: CONTENTS EXECUTIVE SUMMARY ........
Page 5: EXECUTIVE SUMMARY A limited evaluat
Page 9 and 10: should be kept high by absorbing he
Page 11 and 12: output modules for the mixing valve
Page 13 and 14: Manufacturer Product Line Table 4:
Page 15 and 16: maximum for the heat pump, which ap
Page 17 and 18: Model AirTap A7 Operating Mode Tabl
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Page 21 and 22: CONCLUSIONS In this test program, t
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Page 33: Appendix Net Cooling Effect (Ton-ho

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