Hidden Power Drains: Residential Heating and Cooling Fan Power Demand

John Proctor, Proctor Engineering Group, Ltd.
Danny Parker, Florida Solar Energy Center

Keywords

Abstract

This paper compiles power draw, airflow, and static pressure measurements of residential air handlers taken during nine separate field tests of space conditioning systems in Arizona, California, Florida, Nevada, and Canada. The field tests show that air handler power draws exceed the standard assumptions and that the interactions between airflow and cooling capacity combine to degrade overall system efficiency. The findings support conclusions from previous research in Canada that called for a systems approach to improving air handler efficiency. This study reports that fan power in U.S. air conditioners is about 40% higher than estimates used in the DOE Central AC and Heat Pump Test Procedure when rating air conditioners. Some fan power draws approach 1000 watts, similar to adding a 1000 watt electric resistance heater in the air stream. The low assumed power draw: masks the need for continued improvements in air handler and overall system performance; creates operating cost penalties for customers; and increases utility demand on peak. Application of more effective filters without attention to static pressure considerations would exacerbate these effects by raising air horsepower and power draw.

This paper consists of five sections: measured data, comparison of measured data to standard assumptions, air conditioner performance at low airflow, analysis of approaches to correcting low airflow, and conclusions.