1. What is Water Pump Horsepower?

Pump horsepower (HP) is the power required to move a specific volume of water against a given head pressure. Proper HP calculation ensures your pump can handle the required flow and pressure without being oversized (wasting energy) or undersized (failing to meet demand).

2. How Does the Calculator Work?

The calculator uses the standard pump HP formula:

Where:

• \( Q \) — Flow rate in gallons per minute (GPM)
• \( H \) — Total head in feet (ft)
• \( SG \) — Specific gravity of fluid (1.0 for water)
• \( \eta \) — Pump efficiency (typically 0.6-0.85)
• 3960 — Conversion factor (ft-lb/min per HP)

Explanation: The formula calculates the theoretical power needed to move water, then divides by pump efficiency to get actual required HP.

3. Importance of Proper Pump Sizing

Details: Correct HP calculation prevents energy waste, ensures adequate water supply, extends pump life, and avoids cavitation (which can damage pumps).

4. Using the Calculator

Tips:

• Measure flow rate based on your water demand (typical home: 5-12 GPM)
• Calculate total head as static head + friction loss
• Use SG=1.0 for pure water, higher for saltwater or other fluids
• Typical efficiency: 0.7-0.8 for centrifugal pumps

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between brake HP and water HP?
A: Water HP is theoretical power needed, while brake HP includes pump inefficiencies (what the motor must actually deliver).

Q2: How do I account for multiple fixtures running simultaneously?
A: Sum the flow rates of all fixtures that might run together for your Q value.

Q3: What's a typical household pump HP range?
A: Most homes need 0.5-1.5 HP, depending on size and water demand.

Q4: Should I round up the HP when selecting a pump?
A: Yes, choose the next standard size up (e.g., if calculation gives 0.8 HP, select 1 HP pump).

Q5: How does pipe size affect HP requirements?
A: Smaller pipes increase friction loss (higher H value), requiring more HP.