1. What is CFM Calculation?

CFM (Cubic Feet per Minute) is a measurement of airflow volume. It's crucial for determining the effectiveness of exhaust fans in ventilating spaces.

2. How Does the Calculator Work?

The calculator uses the CFM formula:

Where:

• \( Area \) — Cross-sectional area in square feet (ft²)
• \( Velocity \) — Air velocity in feet per minute (ft/min)

Explanation: The formula calculates the volume of air moved by multiplying the area through which air flows by the speed of the airflow.

3. Importance of CFM Calculation

Details: Proper CFM calculation ensures adequate ventilation, prevents moisture buildup, removes odors, and maintains air quality in enclosed spaces.

4. Using the Calculator

Tips: Measure the area of your exhaust opening and the air velocity (use an anemometer if available). Enter values in the appropriate units.

5. Frequently Asked Questions (FAQ)

Q1: What is a good CFM for a bathroom exhaust fan?
A: Generally 50-100 CFM for standard bathrooms. Add 50 CFM for each additional fixture (toilet, shower, etc.).

Q2: How do I measure air velocity?
A: Use an anemometer at the exhaust opening, taking multiple readings for accuracy.

Q3: Does duct length affect CFM?
A: Yes, longer ducts with more bends reduce effective CFM due to increased resistance.

Q4: What's the difference between CFM and ACH?
A: CFM measures airflow volume, while ACH (Air Changes per Hour) measures how often all air in a room is replaced.

Q5: How often should exhaust fans run?
A: Bathroom fans should run during and 15-20 minutes after use. Kitchen hoods should run during all cooking.