In shortHydraulic power P = ρ·g·Q·H. Dividing by pump and motor efficiency gives the electrical power. If efficiency is low, annual energy cost rises quickly.
Total pressure loss (mWC = meters of water column)
This is an example value; enter the unit price on your bill
Result
Preliminary calculation: This tool is for quick sizing and information. In real projects, load calculation, selection and commissioning require engineering calculations and a site survey. Results are approximate values.
Formulas
P_hyd [kW] = ρ × g × Q [m³/s] × H [m] / 1000P_electric = P_hyd / (η_pump × η_motor)Total head is the sum of pipe friction losses and pressure losses in fittings and equipment (heat exchanger, coil, valve). In a closed circuit, static head is not added to the pump load; in an open circuit, it is.
- Speed control by flow rate with a frequency converter saves energy
- The pump operating point should be in the middle of the efficiency curve
- An oversized pump is throttled with a valve and wastes energy
Frequently asked questions
How is pump power calculated?
Hydraulic power is found from flow, head and density; dividing by pump and motor efficiency gives the electrical power.
What is the relationship between mWC and bar?
Approximately 10 mWC = 1 bar (for water).
Why does efficiency matter?
At low efficiency more electricity is used for the same job; annual cost is inversely proportional to efficiency.