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Field and lab testing of residential heat pumps to assess representativeness of fixed-speed and load-based test methods.

Number: 2346

Author(s) : HARLEY B., CHEN Y., DYMOND C., HAMER G., MCWILLIAMS J., YUILL D.

Summary

The potential for improved performance for variable-speed heat pump systems is resulting in their widespread adoption globally. Conventional heat pump and air-conditioning rating methods, such as AHRI 210/240-2023 (2020), were originally developed to characterize the performance of fixed-speed heat pumps, and have been modified over time to include variable-speed equipment. Recently, load-based testing methods such as CSA SPE07:23 have been developed as a response to evidence that fixed-speed tests are inadequate to represent field performance of variablespeed systems. These methods test the heat pump along with its built-in controls, imposing loads that scale with outdoor conditions and allow the heat pump to respond and control the indoor temperature. Laboratory testing has shown that SPE07 results (using the previous edition, EXP07:19) differ substantially from AHRI 210/240 results, raising the question: does SPE07 do a better job representing in-field performance than AHRI 210/240 ? This paper presents preliminary results from a study in which six variable- or multiple-speed heat pumps were installed in three unoccupied, calibrated test houses in Lincoln, Nebraska. Lincoln has a wide range of weather conditions, with heating and cooling design temperatures of -17 °C and 34 °C. Each house had both a ducted and a ductless system installed, which alternated operation throughout the heating and cooling seasons. The systems and houses were instrumented to collect detailed performance data. After the field testing, the same units were tested in a certified laboratory using both the AHRI 210/240 and SPE07 test procedures. This allows a direct comparison of results between the laboratory rating methods and in situ performance, and thus a fair assessment of the representativeness of each rating method using the same tested units. Each set of test results from the field and the lab are mapped to a range of climates, from Hot-Dry to Subarctic, to compare the rating methods to the in-field performance. The objective of load-based testing and rating is to inform heating and cooling efficiency metrics that may prove valuable to consumers, utility programs, and design 2346, professionals, and to improve design practices, performance-based modeling and code compliance. They may also be useful to manufacturers in improving their products’ performance and comfort. Previous lab results have established the merits of the procedure and suggest the value of stakeholder adoption of SPE07, with the goal of improving state and utility program design, home energy ratings, performance-based code compliance and other voluntary activities that support energy efficiency and carbon reduction. To that end, the field and lab data from this project will provide a clear comparative evaluation demonstrating the relevance and potential value of load-based testing to predict realworld performance of variable-speed heat pumps and air conditioners.

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  • Original title: Field and lab testing of residential heat pumps to assess representativeness of fixed-speed and load-based test methods.
  • Record ID : 30033169
  • Languages: English
  • Subject: Technology
  • Source: 2024 Purdue Conferences. 20th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2024/07/17

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