HVAC

Consider Variable Speed Drives on Pumps and Fans

Pump and fan capacities can be reduced and energy saved by using variable speed drives to control their speed. However, don't forget to consider taking low-cost measures to reduce capacity, especially where the pump or fan is running at constant speed most of the time. For instance, if a fan is driven by V-belts, its capacity can be changed by altering the size of the drive pulleys. Similarly, a pump's capacity can be changed by trimming its impeller. These are low-cost alternatives to expensive electric drive modifications. Reductions in both peak and off-peak energy costs can be obtained by using variable speed drives on pumps, fans and compressors that operate at varying loads. The use of these drives will have little impact on demand because they will require the same kilowatts at peak-demand periods as fixed speed drives. They pay off better if the systems they are applied to operate at part load for relatively long hours.