Submersible Well Pump Size Calculator

Pump Size Formula:

\[ \text{Pump Size (HP)} = \frac{\text{Flow Rate (GPM)} \times \text{Head (ft)}}{3960 \times \text{Efficiency}} \]

Calculated Pump Size:

Recommended Standard Size:

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1. What is Pump Size Calculation?

The pump size calculation determines the required horsepower (HP) for a submersible well pump based on water flow requirements, total head pressure, and pump efficiency. Proper sizing ensures efficient operation and prevents pump overload.

2. How Does the Calculator Work?

The calculator uses the standard pump power formula:

\[ \text{Pump Size (HP)} = \frac{\text{Flow Rate (GPM)} \times \text{Head (ft)}}{3960 \times \text{Efficiency}} \]

Where:

\( \text{Flow Rate} \) — Gallons per minute (GPM) required
\( \text{Head} \) — Total dynamic head in feet (vertical lift + friction loss)
\( \text{Efficiency} \) — Pump efficiency (typically 0.5-0.85)
3960 — Conversion constant

Explanation: The formula calculates the theoretical horsepower required to move water at the specified rate against the given head pressure, adjusted for pump efficiency.

3. Importance of Proper Pump Sizing

Details: Correct pump sizing is critical for energy efficiency, system longevity, and reliable water delivery. Oversized pumps waste energy and cause rapid cycling, while undersized pumps can't meet demand.

4. Using the Calculator

Tips:

Measure flow rate based on peak water demand (all fixtures running simultaneously)
Calculate total head as vertical lift plus friction loss in pipes
Typical efficiency for submersible pumps is 60-80% (0.6-0.8)
Always round up to the nearest standard pump size

5. Frequently Asked Questions (FAQ)

Q1: What is total dynamic head?
A: It's the sum of vertical distance from water level to discharge point plus friction losses in pipes, fittings, and valves.

Q2: How do I determine my flow rate needs?
A: Add up the flow rates of all fixtures that might run simultaneously. Typical home needs 5-12 GPM.

Q3: What are standard pump sizes?
A: Common submersible pump sizes are 0.5, 0.75, 1, 1.5, 2, 3, 5, 7.5, and 10 HP.

Q4: Why is efficiency important?
A: Higher efficiency pumps (0.7+) use less electricity for the same output, saving energy costs.

Q5: Should I add a safety factor?
A: Yes, it's common to add 10-20% to the calculated HP to account for future needs or calculation uncertainties.