Grundfos CR vs CRE — Fixed Speed vs Variable-Speed E-Pump
Should you specify a fixed-speed Grundfos CR or a variable-speed CRE E-Pump? A full comparison of cost, efficiency, control modes and total cost of ownership.
The Grundfos CR and CRE share the same hydraulic pump end. The difference is the motor and drive package: CR uses a fixed-speed three-phase induction motor; CRE bolts an MLE IE5 permanent-magnet motor with an onboard variable frequency drive (FCC) on top. Beyond that single change, everything downstream — control modes, energy bill, footprint, wiring, BMS integration — is different.
Head-to-Head Specification Comparison
| Feature | Grundfos CR | Grundfos CRE |
|---|---|---|
| Pump end | Same CR / CRI / CRN end | Same CR / CRI / CRN end |
| Motor | Standard NEMA TEFC induction (IE3) | MLE permanent-magnet (IE5) |
| Drive | Direct online or external CUE VFD | Integrated FCC variable frequency drive |
| Speed control | Fixed (or variable with external VFD) | Variable — built-in |
| Constant-pressure mode | Requires external controller | Built-in |
| Proportional-pressure mode | Not possible directly | Built-in |
| BMS / BACnet / Modbus | Via CIM/CIU on external VFD | Native via plug-in CIM module |
| Energy savings (variable demand) | Baseline (throttled valve) | 30–70 % |
| Footprint | Pump + separate VFD cabinet | Pump only — no cabinet |
| Initial cost | Lower | 15–25 % higher than CR + CUE |
| Dry-run protection | Via LiqTec add-on | Built-in (sensorless) |
When to Choose Each
Choose Grundfos CR (Fixed Speed) When…
- Duty point is constant — boiler feed at constant load, dosing skid, irrigation at design flow.
- Budget is tight and the system has no variable-demand profile.
- The site has a building-wide VFD or a separate VFD program standard.
- Replacement of an existing fixed-speed CR in a known-good design.
Choose Grundfos CRE (E-Pump) When…
- Demand modulates more than 20 % — commercial pressure boosting, HVAC, modulating boiler feed, variable irrigation.
- BMS / SCADA integration via Modbus, BACnet, PROFIBUS or EtherNet/IP is needed (CIM plug-in module).
- Floor space is constrained and you want to avoid a separate VFD cabinet.
- Long-term energy cost is a primary driver — IE5 + variable speed = best TCO.
The Third Option: CR + CUE External VFD
If you already own a CR or your specification mandates an external drive, pair the CR with a Grundfos CUE. The CUE is a dedicated pump VFD with the same pump-specific control modes as the CRE (constant pressure, proportional pressure, constant flow, dry-run protection, pipe-fill). It is the most cost-effective way to retrofit installed CR pumps to variable speed.
Energy Savings Example
A typical commercial booster pump runs at 60 % average load with peaks at 100 %. Compared to a fixed-speed CR with a throttling valve:
- Fixed-speed CR + valve: baseline — call it 100 % electrical input.
- CR + CUE VFD: ~55–60 % of baseline (40 % savings).
- CRE E-Pump (IE5): ~45–50 % of baseline (50 % savings).
At $0.12/kWh and a 10 HP pump running 6,000 hours/year, the difference is roughly $3,200/year in favor of the CRE versus a throttled CR.
Bottom Line
For new installations with any variable demand, the CRE is the better choice: smaller footprint, better energy use, native BMS integration and faster commissioning. Stick with a fixed-speed CR only when the duty is truly constant or when an external VFD program is mandated.
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