Understanding Pump Flow, Head, Power and Hydraulic Efficiency

Quick Engineering Answer:

Pump flow (m³/h) and head pressure (m) are inversely related along a performance curve. As pipe friction and filter resistance increase (higher head), water flow decreases. The Best Efficiency Point (BEP) is the duty point where the pump converts the highest percentage of electrical power into fluid kinetic energy. Tradeflo pumps are engineered with CFD impellers to place the BEP exactly between 8m and 12m head — South Africa's standard residential plumbing range.

Technical Overview & Sizing Principles

Engineering breakdown of head pressure vs flow curves, duty points, Best Efficiency Point (BEP), and power factor. In Southern Africa's demanding climate, water circulation systems must account for elevated water temperatures, high summer ambient heat inside enclosed pump housings, pipework friction losses, and seasonal lightning surges.

Engineering Comparison Table

Duty Point	Head (m)	Flow (m³/h)	Power Draw (W)	Hydraulic Efficiency (%)
Open Discharge (Zero Head)	0.0 m	22.0 m³/h	1030 W	0.0% (No useful pressure)
Light Resistance (Clean Filter)	6.0 m	18.5 m³/h	1000 W	35.2%
Best Efficiency Point (BEP)	10.0 m	15.0 m³/h	980 W	41.8% (Maximum Efficiency)
Heavy Resistance (Dirty Filter)	14.0 m	5.0 m³/h	860 W	22.2% (Backwash Required)

Best Practice Installer Recommendations

Plumbing Diameter: Always utilize 63mm suction plumbing where pipe runs exceed 10 metres to keep fluid velocity under 1.8 m/s.
Ventilation: Ensure fibreglass pool boxes provide at least 150mm clearance around the motor cooling cowl for airflow.
Filter Matching: Never exceed the maximum recommended flow velocity of the silica sand bed (D500: max 12 m³/h; D600: max 18 m³/h).

Published by: UPP Pumps Engineering Desk (KZN) Review Date: August 2026 • Rev 2.1

Note: Calculations are based on clean plumbing at sea level. High-altitude installations require standard derating.

Relevant Products

Tradeflo Pool Pumps (0.56 – 1.12kW) Agriflo Saltwater Pumps Tradeflo D500 & D600 Filters Drop-in-Drive Direct Retrofits

Trade Reseller Portal

Approved installers and pool shops can access wholesale pricing and direct ordering.

Apply for Trade Account