This study developed a method to estimate the energy performance of blowers that are driven by electronically commutated motors (ECMs) in residential gas furnaces based on rotational speeds and blower wheel dimensions. As the first step, the airflow, power, and rotational speed of five different ECM blowers from three manufacturers were measured over a range of external static pressures (ESPs) from 0.1 to 1.2 in. w.g. (25 to 300 Pa) in a well-instrumented laboratory environment with a calibrated nozzle airflow chamber. Then, the energy performance of each ECM blower was determined from the airflow and power measurements and characterized in terms of efficacy, which is the ratio of blower power to airflow rate. The investigation of the relationship between rotational speed and blower efficacy led to the correlation of efficacy with the blower Reynolds number that is dependent on rotational speed and blower wheel dimensions.

Results show that the efficacy of ECM blowers can be accurately predicted by using the developed exponential correlations as evidenced by the high R2 values ranging from 0.975 to 0.981. Furthermore, a comparison between the predicted and experimentally determined efficacies shows that 92% of the predicted data points are within +/-10% of the experimentally determined results.

Results generated from this study provide a method to predict the energy performance in terms of efficacies for ECM blowers based on the knowledge of rotational speed and blower wheel dimension. In addition, the experimental data and correlations produced in this study can be used to model the ECM blower efficacy behaviors over a range of rotational speed.