1. What is Rectangular Duct Area Calculation?

Rectangular duct area calculation determines the cross-sectional area needed for proper airflow in HVAC systems based on the required airflow (CFM) and desired air velocity.

2. How Does the Calculator Work?

The calculator uses the duct area formula:

Where:

• \( CFM \) — Airflow in cubic feet per minute
• \( Velocity \) — Air velocity in feet per minute

Explanation: This formula calculates the minimum cross-sectional area required to achieve the desired airflow at the specified velocity.

3. Importance of Duct Sizing

Details: Proper duct sizing is crucial for efficient HVAC system operation, ensuring adequate airflow while minimizing pressure drops and energy consumption.

4. Using the Calculator

Tips: Enter CFM value in cubic feet per minute and velocity in feet per minute. Both values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical velocity range for HVAC ducts?
A: For residential systems, velocities typically range from 600-900 ft/min for supply ducts and 500-700 ft/min for return ducts.

Q2: How do I convert area to actual duct dimensions?
A: Once you have the required area, you can determine appropriate width and height combinations that maintain proper aspect ratios (typically 1:1 to 1:4).

Q3: Why is proper duct sizing important?
A: Proper sizing ensures efficient airflow, reduces noise, minimizes energy consumption, and prevents system strain.

Q4: What factors affect duct sizing besides CFM and velocity?
A: Duct material, length, number of bends, and static pressure requirements also influence final duct sizing decisions.

Q5: Can this calculator be used for round ducts?
A: This formula gives area which applies to all duct shapes. For round ducts, you would then calculate the diameter needed to achieve that area.