406 produce chilled water that is circulated throughout system 400 as well as to valves 414 416 and 418 and cooling coils 420 422 and 424 by pumps 410 and 412 when water passes through cooling coils 420 422 and 424 it is warmed up by the air the water is then once again redistributed through the pump system in a cyclical manner and is cooled down by chillers 404 and 406 vfds 408 amp 426 control the speed of pumps 410 and 412 to maintain the differential pressure across cooling coils 420 422 and 424 control device 302 is configured in communication with vfds 408 and 426 said control device controls the manner in which pumps 410 and 412 are staged it is also configured to control the speed of said pumps as illustrated in fig4 the pumps are configured in parallel as shown in fig3 control device 302 can be installed in both systems 300 and 400 before control device 302 can be used the user must first configure control device 302 with the specific data for the system in which it will be implemented for example when the system is implemented in air handling units the user pre programs into device 302 data comprising but not limited to the fan performance curve and high and low load airflow rates when the system is implemented in chilled water pump systems data pre programmed into device 302 may include but not be limited to the chilled water pump performance curves and the high and low load water flow rates thus the control method of device 302 differs depending upon the system of.