1. What is a Pressure Tank Size Calculator?

Definition: This calculator determines the minimum required size for a pressure tank based on system flow rate, pump runtime, and desired start frequency.

Purpose: It helps ensure proper water system operation by preventing excessive pump cycling while maintaining adequate pressure.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( V_{tank} \) — Required tank volume (gallons)
• \( Q_{avg} \) — Average system flow rate (gallons per minute)
• \( t_{min} \) — Minimum acceptable pump runtime (minutes)
• \( n_{starts} \) — Maximum allowable pump starts per hour

Explanation: The formula calculates the drawdown capacity needed to maintain system pressure between pump cycles while limiting motor starts to prevent overheating.

3. Importance of Proper Tank Sizing

Details: Correct tank sizing extends pump life, maintains consistent water pressure, and reduces energy consumption by minimizing frequent cycling.

4. Using the Calculator

Tips: Enter the average flow rate (gpm), minimum runtime (default 1 min), and maximum starts per hour (default 6). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is pump runtime important?
A: Minimum runtime (typically 1-2 minutes) ensures the pump motor doesn't overheat from short cycling.

Q2: What's a typical maximum starts per hour?
A: Most pumps should start no more than 6-10 times per hour, with 6 being conservative for longer motor life.

Q3: How do I determine my average flow rate?
A: Calculate based on fixture count or measure actual usage during peak demand periods.

Q4: Does this account for pressure settings?
A: This provides the drawdown volume. Actual tank size will be larger based on your pressure switch settings (typically 20/40, 30/50, or 40/60 psi).

Q5: Should I round up the tank size?
A: Yes, always select the next standard tank size above your calculated value for best performance.