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CU 302 is a control and communication unit specially developed for the SQE submersible pumps in constant-pressure applications. It is intended for controlling and monitoring SQE pumps using power line communication, so the control unit communicates with the pump via the power cable and nothing additional is run down the borehole.
The controller operates according to the water pressure measured by a pressure sensor in the installation. When water is consumed, the system detects flow together with pressure change; the controller starts the pump, and pump performance and water flow are controlled by changing the pump speed. The system maintains a constant pressure within the maximum pump performance in spite of varying water consumption.
The factory setup is constant pressure over 2 to 5 bar (20 to 100 PSI) with a setpoint of 3 bar (50 PSI), CIO 1 configured for an analog sensor and CIO 2 for digital outputs; when the pump is running the output changes contact position. Input signals can be analog sensors or digital switches, and the controller can be used in a range of other applications by changing its configuration: level control filling, level control emptying, pressure control on a digital or an analog input, pump out, and pump monitoring.
Operating indication sits on the front of the controller — power on, pump running, and the Grundfos Eye showing pump status — alongside alarm and warning indication. CU 302 reports dry running and service-needed conditions including no contact to the pump, overvoltage, overtemperature and overload. In a constant-pressure installation it works with a 2 gal (8 litre) diaphragm tank rather than a conventional pressure tank, because the pump follows demand instead of cycling between two switch settings.
| Configuration | Pressure sensor | Units | Approval | Part No. |
|---|---|---|---|---|
| CU 302 UL, complete | Not included | PSI | UL | 92799799 |
| CU 302 UL with PSI sensor | Included | PSI | UL | 92817764 |
Both variants are the North American UL build reading in PSI. Grundfos also lists bar-reading CE variants — 92799797 without sensor and 92817763 with sensor — which are the CE-market builds and are not the ones to order in North America. A constant-pressure installation needs a sensor: order the with-sensor part number, or the without-sensor part number plus a transducer.
| Specification | Value |
|---|---|
| Supply voltage | 90-240 VAC -10 % / +6 %, PE |
| Frequency | 50/60 Hz |
| Rated current | Maximum 12.5 A |
| Mains fuses / backup fuse | Maximum 16 A |
| Power consumption | Maximum 25 W |
| Overvoltage category | III |
| Field wiring | Minimum 20 AWG rated 140 °F or higher. Copper, copper-clad aluminum or aluminum conductors |
| Analog input | 0-10 V, 0-5 V or 0.5-3.5 V at 100 kΩ load; 0-20 mA or 4-20 mA at maximum 2 V drop. Under-range and over-range raise a warning or alarm |
| Analog output | 0-10 V at maximum 20 mA; 0-20 mA or 4-20 mA into 500 Ω or less |
| Default control mode | Constant pressure, 2-5 bar (20-100 PSI), setpoint 3 bar (50 PSI) |
| Other control modes | Level control filling, level control emptying, pressure control on digital input, pressure control on analog input, pump out, pump monitoring |
| Pressure sensor range | 0-6 bar (0-120 PSI) analog |
| Transceiver | RS-485 |
| Protocol | GENIbus over the pump power cable |
| Wireless | Bluetooth to the Grundfos GO app |
| Enclosure class | Type 1 / Type 3R on the UL version (IP55 on the CE version) |
| Ambient temperature, operating | -4 °F to +122 °F |
| Ambient temperature, storage | -22 °F to +140 °F |
| Relative air humidity | 5-95 % |
| Dimensions | 9.1 in high x 6.3 in wide x 3.8 in deep |
| Weight | 2.69 lb |
| Marking | UL |
| Radio noise | Tested to EN 55014 and EN 55014-2 |
CU 302 controls Grundfos SQE pumps only. It will not control an SQ, which has no communication, and it must not be used with any pump outside the SQE range.
Order by part number. CU 302 UL, complete, without sensor — 92799799. CU 302 UL with PSI sensor — 92817764.
Related parts. CU 302 pressure transducer, 0-120 PSI, 1/2 in NPT — 92506685. SQ, SQE cable kit, 14 AWG 5 ft NSF, motor model C — 97778332. SP, SQ, SQE wrench — 99588350. SQ, SQE flow sleeve, complete — 98148594.
What the installation needs. An SQE pump, a CU 302, a pressure sensor, a 2 gal diaphragm tank and a mains switch. The SQE pump is not included with the controller.
SQ and SQE: Constant Pressure Pump Overview (4:02)
Installing a Grundfos SQE Constant Pressure System (5:22)
Grundfos CU 202 and CU 302 Control Units — Product Animation (1:29 · Dutch narration)
Videos produced by Grundfos and hosted on YouTube.
The free Grundfos HOME app gives you full control of your water system from an iOS or Android phone. It reports pump information around the clock, sends alert notifications on important events so you can act before the water goes off, and carries a built-in watering calendar with an internal clock so irrigation routines run to schedule without a timer. Installer details are stored in the app, so whoever set the system up is one tap away.
Grundfos HOME is a free app from Grundfos Holding A/S. It connects through the CU 302 control unit, which is required and is sold separately, and Bluetooth must be enabled on the CU 302 operating panel before pairing. Installers and service technicians use a separate free Grundfos app, Grundfos GO, as the commissioning and diagnostic tool; ask us for the link if you need it.
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