States that existing wet heating and cooling (hydronic) systems can be converted to variable-speed pumping operation if a careful review is made of the basic principles of the system design, the flow requirements to the various zones the control methods employed, the zone and terminal balancing needs and the system load distribution. Explains how centrifugal pumping systems employing squirrel-cage motors of NEMA-B type can be retrofitted with pump controls that will give a high degree of control and operating power savings and result in a short payback on the investment.

KEYWORDS: Heating, cooling, pumps, water pumps, constant, variable, speed.