1. What is CFM Calculation?

CFM (Cubic Feet per Minute) calculation determines the volume of air flowing through a duct system. It's essential for HVAC system design, ventilation planning, and ensuring proper air circulation in buildings.

2. How Does the Calculator Work?

The calculator uses the basic air flow equation:

Where:

• \( CFM \) — Cubic Feet per Minute (air flow rate)
• \( \text{Duct Area} \) — Cross-sectional area of duct in square feet
• \( \text{Velocity} \) — Air velocity in feet per minute

Explanation: This fundamental equation relates the physical dimensions of the duct to the speed of air movement, providing the volumetric flow rate.

3. Importance of Air Flow Calculation

Details: Accurate CFM calculation is crucial for proper HVAC system sizing, energy efficiency, indoor air quality, and compliance with building codes and ventilation standards.

4. Using the Calculator

Tips: Enter duct area in square feet and velocity in feet per minute. Both values must be positive numbers for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical CFM range for residential HVAC?
A: Residential systems typically range from 400-2000 CFM depending on the size of the home and system capacity.

Q2: How do I measure duct area?
A: For rectangular ducts: width × height (in feet). For round ducts: π × (radius in feet)².

Q3: What velocity is recommended for duct systems?
A: Typical velocities range from 600-900 fpm for supply ducts and 500-700 fpm for return ducts in residential applications.

Q4: Why is CFM important in HVAC design?
A: Proper CFM ensures adequate air distribution, maintains comfort levels, prevents system strain, and optimizes energy consumption.

Q5: Can this calculator be used for commercial systems?
A: Yes, the same formula applies, though commercial systems typically handle much higher CFM values and may have different design considerations.