How to Measure Fan Efficacy (Blower Performance)

MeasureQuick shows fan efficacy in its measurements when you use a power meter (such as the RedFish IDVM550). The power meter measures the wattage (volts x amps x power factor) and stacks it up to the CFM produced by the blower. You can figure out how much CFM the unit is producing by using a fan table and the static pressure reading. If you don’t have that at your disposal, you may have to use a TrueFlow grid, do a duct traverse, or use an airflow hood to get your CFM measurement.

In general, we’re shooting for a fan efficacy rating at or better than (below) 0.58. Both PSC motors and ECMs will experience a decrease in fan efficacy if the filter or evaporator coil gets dirty; wattage will have to increase to overcome the restrictions.

To use measureQuick, you need to connect your power meter to the app via Bluetooth. We recommend using a meter that also measures power quality, as it can account for the power factor. Anything with a power factor less than 1 will yield a wattage value below the volt-amps, and low power factors are common in fan motors.