VSDs reduce energy consumption by operating at speeds that vary over time based on changing loads. Standard pump and fan systems always run at full speed, consuming more electricity than required to do the job. A variable speed drive slows a fan or pump down when the actual load decreases.
The savings from a variable speed drive in these applications increases exponentially as the load decreases. As a result, a small decrease in speed produces a relatively large increase in savings. For example, a 20% reduction in flow can yield a savings of 35% or more.
VSDs are ideally suited for HVAC applications because the demand on heating and cooling systems can vary with outside temperature, building occupancy, and production level. Other effective applications include:
- Boiler draft fans serving boilers with varying loads
- Exhaust fans where the necessary flow rate varies with temperature, such as oven and dryer exhaust fans
- Manufacturing applications where load varies with production