This concept is the least studied part of a refrigeration system. Here are a few tips for maintaining proper airflow:
There are three types of fans to remember:
The propeller fan: If resistance is added, the cfm will be reduced, thereby reducing the air to the propeller. This will cause the air to flow back through the center of the fan, increasing the wattage of the motor.
The axial fan: This has the same design as the propeller fan. However, the axial fan prevents air from passing on a buildup of air resistance through the center of the fan. This prevents the increase in wattage of the fan motor that occurs in propeller fans.
The centrifugal fan: This cylindrical, disk-shaped fan has blades running parallel to the axis. On an increase in air resistance, there is no increase in wattage.
Finally, a rule of thumb:
Schaub is president of Schaub Consulting, Medford, NJ.
Publication date: 08/06/2001