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A Curve-Based Mixed System Rating Method for Unitary Air Conditioners



William V. Payne, Piotr A. Domanski


The curve-based method was evaluated based on performance predictions for nine mixed systems, which were also tested by an independent testing laboratory. Capacity predictions were within 5% of the tested values for six of nine mixed systems, and four of nine SEER predictions were within 5% of the tested SEERs. Predictions for SEER showed an underprediction bias due to the wide variation of possible values for the cyclic degradation coefficient (CD) and the necessity of assuming a conservative value of CD in mixed system rating calculations. The report includes detailed test data for tested evaporators and an uncertainty analysis of the rating methodology.
Journal of Research (NIST JRES) - 7225
Report Number


building automation and control, cybernetic building systems, direct digital control, energy management systems, fault detectgion and diagnostics


Payne, W. and Domanski, P. (2005), A Curve-Based Mixed System Rating Method for Unitary Air Conditioners, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed March 2, 2024)
Created May 2, 2005, Updated February 19, 2017