1. What is Duct Area Calculation?

Duct area calculation is a fundamental HVAC engineering process that determines the cross-sectional area required for air distribution systems based on airflow rate and velocity.

2. How Does the Calculator Work?

The calculator uses the duct area formula:

Where:

• \( Area \) — Duct cross-sectional area (ft²)
• \( CFM \) — Airflow rate (cubic feet per minute)
• \( Velocity \) — Air velocity (feet per minute)

Explanation: This formula calculates the required duct area to maintain proper airflow while achieving desired velocity for efficient system operation.

3. Importance of Duct Sizing

Details: Proper duct sizing is crucial for HVAC system efficiency, noise control, energy conservation, and maintaining adequate airflow throughout the system.

4. Using the Calculator

Tips: Enter CFM in ft³/min and velocity in fpm. Both values must be positive numbers. Typical residential duct velocities range from 600-900 fpm for main ducts and 400-700 fpm for branch ducts.

5. Frequently Asked Questions (FAQ)

Q1: What is the ideal velocity for duct systems?
A: Residential systems: 600-900 fpm (main), 400-700 fpm (branch). Commercial systems: 1000-2000 fpm depending on application and noise requirements.

Q2: How does duct shape affect area calculation?
A: The formula calculates cross-sectional area. For rectangular ducts, area = width × height. For round ducts, area = π × (diameter/2)².

Q3: What are common CFM requirements?
A: Typical residential requirements: 400-2000 CFM depending on home size. Commercial systems can range from 2000-50,000+ CFM based on building size and occupancy.

Q4: Why is proper duct sizing important?
A: Undersized ducts cause high velocity, noise, and pressure drop. Oversized ducts waste materials and may not maintain proper air distribution.

Q5: How do I convert area to duct dimensions?
A: For rectangular ducts: choose width and height that multiply to the calculated area. For round ducts: diameter = 2 × √(area/π).