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Application of a Linear Fit Rating Method for Mixed Single-Speed Unitary Air Conditioners



William V. Payne, Piotr A. Domanski


A method employing the simultaneous solution of two linear fits is used to determine the rated cooling capacity and seasonal energy efficiency ratio, SEER, of outdoor unit and indoor unit air-conditioner combinations not previously tested as a complete system. The information presented here outlines the formulation of this method, verification of the method, and application of the method to produce ratings. For the examples presented here, the calculated cooling capacity and SEER ratings were within ± 3 % and ± 5 %, respectively, of manufacturer test data. This method applies to split system residential air-source unitary air conditioners and heat pumps. The outdoor section is characterized by a single-speed compressor with single-phase, electric power usage. The rated cooling capacity of the highest sales volume combination used in obtaining the ratings of the mixed system must be less than 19 050 W (65 000 Btu h-1). This method could be applied to determining the cooling capacity of any air-conditioner if the only independent variables were indoor and outdoor temperatures; extending this method to two-speed or variable speed systems should produce representative cooling capacity linear fits for a given compressor speed and evaporator air flow rates.
Proceedings Title
2013 ASHRAE Winter Conference in Dallas
Conference Dates
January 26-30, 2013
Conference Location
Dallas, TX


cooling performance, heat pump performance, mixed system rating


Payne, W. and Domanski, P. (2013), Application of a Linear Fit Rating Method for Mixed Single-Speed Unitary Air Conditioners, 2013 ASHRAE Winter Conference in Dallas , Dallas, TX, [online], (Accessed June 24, 2024)


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Created January 28, 2013, Updated February 19, 2017