The HZSE variable frequency centrifugal pump integrates a variable frequency drive (VFD) directly onto the motor, delivering automatic constant-pressure control and significant energy savings without the complexity of an external control panel. Sharing the same extended-shaft, no-coupling platform as the standard HZS, the HZSE adds intelligent speed regulation to single-stage centrifugal pump simplicity.
Built-In VFD — Automatic Constant Pressure
A factory-mounted VFD unit on the motor enables closed-loop PID control via a pressure transducer installed on the discharge pipe. The controller continuously compares actual discharge pressure against the setpoint and adjusts motor speed in real time. When demand drops — for example, at night in a residential building — the pump slows to a fraction of full speed, eliminating the waste of throttling or bypass control.
Key control features include:
- PID constant-pressure mode — Maintains discharge pressure within a tight band regardless of flow variation.
- Sleep/wake function — At ultra-low demand, the pump enters sleep mode and auto-restarts when pressure falls below the wake threshold.
- Soft start and soft stop — Reduces inrush current by up to 80% and eliminates water-hammer risk on shutdown.
- Dry-run protection — Stops the motor automatically when suction is lost, preventing seal damage.
- Fault diagnostics and alarms — The VFD stores fault codes (overcurrent, overvoltage, overheating) for rapid troubleshooting.
Energy Savings: Fixed-Speed vs VFD Over 10 Years
The following comparison illustrates the cost difference between a conventional fixed-speed HZS pump with throttling valve control and an HZSE VFD pump in a typical building water-boosting application (rated 37 kW, average 60% load factor, 12 hours/day, 365 days/year).
| Item | HZS Fixed Speed (Throttle) | HZSE VFD Pump |
|---|---|---|
| Rated motor power | 37 kW | 37 kW |
| Control method | Valve throttling | Variable speed |
| Average power draw | ~32 kW | ~19 kW |
| Annual energy consumption | ~140,160 kWh | ~83,316 kWh |
| Annual electricity cost (¥0.8/kWh) | ¥112,128 | ¥66,653 |
| 10-year energy cost | ¥1,121,280 | ¥666,530 |
| Estimated VFD unit cost (one-time) | — | ¥18,000 |
| 10-year net saving | — | ¥436,750 |
| Energy saving percentage | — | 40% |
Note: Figures are indicative and based on typical operating profiles. Actual savings depend on load variability, electricity tariff, and system design. Contact Hongjiu for a project-specific energy audit.
Technical Specifications
| Parameter | Value |
|---|---|
| Pump type | Horizontal, single stage, end-suction centrifugal with built-in VFD |
| Flow range | 2–120 m³/h |
| Head range | 5–50 m |
| Inlet/outlet sizes | DN32–DN100 |
| Wetted parts material | AISI 304 stainless steel |
| Motor efficiency class | IE3 |
| VFD integration | Factory-mounted, IP55 |
| Control mode | PID constant-pressure, sleep/wake, soft start/stop |
| Pressure setting range | 0.1–1.0 MPa (adjustable) |
| Maximum working pressure | 1.6 MPa (16 bar) |
| Medium temperature range | -10 °C to +80 °C |
| Protection functions | Dry-run, overcurrent, overvoltage, overheating |
Applications
Building water-supply boosting — The constant-pressure mode eliminates pressure fluctuations on upper floors as occupancy changes throughout the day.
HVAC systems with variable occupancy — Shopping malls, office buildings, and schools experience large seasonal and daily load swings. The HZSE adjusts pump speed to match the actual cooling or heating demand.
Domestic pressure stabilization — Hotels, hospitals, and apartment complexes benefit from consistent shower and tap pressure regardless of how many fixtures are open simultaneously.
Hotel shower systems — Guest complaints about weak morning showers disappear when a VFD pump maintains set pressure at peak demand.
Extended Shaft Advantage
Like the standard HZS, the HZSE uses the extended-shaft, no-coupling design. The VFD is mounted on the motor, not on a separate pump bracket, so the compact layout is preserved. No coupling alignment, no coupling guard, fewer wearing parts, and lower vibration — the same mechanical simplicity with added intelligent control.
Related Products
- HZS Standard Single Stage Centrifugal Pump
- HZS Stainless Steel Centrifugal Pump — full series overview
Frequently Asked Questions
What energy savings can I realistically expect?
In applications with variable demand — building boosting, HVAC secondary loops, and domestic supply — savings typically range from 20% to 40%. Systems with flat, constant loads see minimal benefit because the pump runs at or near full speed most of the time. Hongjiu provides complimentary energy-saving calculations based on your operating profile.
Can I retrofit the HZSE VFD to an existing fixed-speed system?
Yes. The HZSE is a drop-in replacement for standard HZS pumps. If you already have HZS units installed, swapping in HZSE models requires only adding a pressure transducer and setting the target pressure on the VFD keypad. No external control cabinet or PLC is needed.
What is the pressure setting range?
The PID setpoint is adjustable from 0.1 MPa to 1.0 MPa (1–10 bar) via the VFD keypad or remote interface. For building boosting, typical setpoints fall between 0.3 MPa and 0.6 MPa depending on building height and pipe losses.
