See What Throttling a Valve Is Costing You
Free tool to calculate the energy cost savings of running a pump with a VFD instead of throttling a valve. Enter your numbers, see the payback instantly.
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VFD Cost Savings Calculator
If your pump is running at full speed while a throttling valve cuts flow back to where you need it, you’re paying for energy you never use. Our free VFD Cost Savings Calculator shows you exactly how much a variable frequency drive (VFD) could save compared to valve throttling — in dollars, kWh, and payback time — using your own pump, flow, and electricity rate data.
Why Throttling a Valve Wastes Energy
A pump running at constant speed with a partially closed valve still consumes power as if it were delivering full flow. The pump does the work; the valve just fights it. A VFD instead slows the motor down to match the flow you actually need, and because pump power follows the affinity laws (power scales roughly with the cube of speed), even a modest speed reduction can produce a large cut in energy use
What This Calculator Does
The calculator compares two scenarios side by side:
- Throttled operation — pump running at full speed, valve partially closed to control flow
- VFD operation — pump speed reduced to match the same flow
It then estimates:
- Energy consumption (kWh) for each scenario
- Annual energy cost difference based on your electricity rate
- Estimated VFD payback period based on equipment and installation cost
- Percentage energy reduction
How to Use It
Enter a handful of numbers you likely already have on hand:
- Motor horsepower or kW rating
- Current flow rate and the flow rate you actually need
- Hours of operation per year
- Your electricity rate ($/kWh)
- Estimated VFD equipment/installation cost (optional, for payback calculation)
The calculator runs the comparison instantly in your browser — no signup, no installation, and no data sent anywhere.
Who This Is For
This tool is built for plant engineers, maintenance and reliability teams, energy auditors, and anyone evaluating a VFD retrofit on a throttled centrifugal pump system. It’s especially useful when building a business case for capital approval, since it turns the affinity-laws math into a concrete dollar figure and payback timeline.
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Want to learn more? Zenco offers:
- In-person certification classes (multiple locations)
- Live online classes
- Self-paced pre-recorded video courses
- Private courses on-site or online
- Shop Courses
FAQ
How much energy can a VFD save compared to a throttling valve? Savings vary by system, but because pump power roughly follows the cube of speed, even a 20% flow reduction via a VFD can cut energy use by 40–50% compared to achieving the same flow by throttling a valve at full pump speed.
Is the VFD Energy Savings Calculator really free? Yes. It runs directly in your browser with no cost, signup, or software installation required.
What information do I need to use the calculator? Motor horsepower, current and required flow rates, annual operating hours, and your local electricity rate. VFD cost is optional and only needed if you want a payback period estimate.
