4" Grundfos CU321 Constant Pressure SmartFlo Systems

Featuring Grundfos Stainless Steel 4" Pumps and Motors

The highly efficient, reliable, and proven drive is designed to extend the range of our SmartFlo family of Constant Pressure Systems from ½ hp through 5hp.

Main applications:

  • Domestic and light commercial water supply
  • Irrigation
  • Livestock watering
  • Water transfer

SmartFlo CU321 Constant Water Pressure System consists of:

  • Compact, efficient, and reliable CU321 variable frequency drive
  • Rugged stainless steel pump end and proven, reliable 3-phase 230V motor
  • Pressure sensor
  • Minimum 4 gallon diaphragm tank

CU321 features the following:

  • A complete solution from one manufacturer
  • Easy setup – simply select pump model and choose pressure set point
  • System design approach – CU321 is calibrated to the Grundfos motor and pump, eliminating doubts about proper pump or motor selection
  • Four pump choices – offered in most popular sizes, both 3 and 5hp: 16, 25, 40 and 75gpm
  • Matched pump and motor – 3hp pump on 3hp motor and 5hp pump on 5hp motor.
  • Respects original operating designs – operates pump and motor within its designed RPM and hp ratings
  • Built-in protection features – Soft start, dry run, overload, over/under voltage, sensor alarm
  • Wide voltage range – 3hp and 5hp input: single phase 208 – 240VAC

1PH 3HP CU321 SmartFlo Systems 1PH 5HP CU321 SmartFlo Systems


1PH 3HP 16S30-24
Smartflo System


$2729

1PH 5HP 16S50-38
Smartflo System


$3674

1PH 3HP 25S30-15
Smartflo System


$2729

1PH 5HP 25S50-26
Smartflo System


$3674

1PH 3HP 40S30-9
Smartflo System


$2729

1PH 5HP 40S50-15
Smartflo System


$3674

1PH 3HP 75S30-5
Smartflo System


$2729

1PH 5H 75S50-8
Smartflo System


$3674






3PH 5HP CU321 SmartFlo Systems

3PH 5HP 16S50-38
Smartflo System


$3199

3PH 5HP 25S50-26
Smartflo System


$3199

3PH 5HP 40S50-15
Smartflo System


$3199

3PH 5HP 75S50-8
Smartflo System


$3199