Hidden Power Drains: Trends in Residential Heating and Cooling Fan Watt Power Demand

This paper compiles power draw, air flow, 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 devices do not meet basic performance standards and that the interactions between components combine to further 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 consumption 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. Fan power draws approach 1000 watts, similar to adding a 1000 watt electric resistance heater in the air stream. The low assumed watt draw masks the need for continued improvements in equipment performance and creates operating cost penalties - not advantages - for customers. Application of high-efficiency filters without attention to static pressure considerations would exacerbate these effects by raising air horsepower and watt draw. The paper summarizes the field test data and suggests a systems-based approach for component and product improvement.