The 00 Series Variable Speed/Variable Voltage Circulator is designed to operate the pump at different speeds based on an externally-generated analog voltage signal input. 00 Series Variable Speed/Variable Voltage Circulator’s reliable operation, ease of installation and integration to DDC or building management systems allows for a wide variety of HVAC applications, such as maintaining a pressure differential or a setpoint temperature. The control accepts a 0-10 V(dc), 0-20 mA, 2-10 V(dc), or 4-20mA signal.