1. What is Exhaust Fan CFM?

CFM (Cubic Feet per Minute) is a measurement of airflow volume that indicates how much air an exhaust fan can move. It's crucial for determining the appropriate fan size for effective ventilation in a space.

2. How Does the Calculator Work?

The calculator uses the CFM formula:

Where:

• \( CFM \) — Cubic feet per minute (fan capacity)
• \( V \) — Volume of the room (ft³)
• \( ACH \) — Air changes per hour (recommended ventilation rate)

Explanation: The calculation converts the hourly air change requirement (ACH) to a per-minute rate (CFM) by dividing by 60 minutes.

3. Importance of Proper Ventilation

Details: Proper ventilation is essential for removing pollutants, controlling moisture, maintaining air quality, and ensuring occupant comfort and health.

4. Using the Calculator

Tips: Measure your room's length, width, and height to calculate volume (L×W×H). Select appropriate ACH based on room type (kitchens: 8-15, bathrooms: 6-10, workshops: 10-20).

5. Frequently Asked Questions (FAQ)

Q1: What is a good CFM for a bathroom exhaust fan?
A: Typically 50-100 CFM for standard bathrooms (8' ceiling). Larger bathrooms or those with high humidity may need more.

Q2: How do I calculate room volume?
A: Multiply length × width × height in feet. For irregular spaces, divide into rectangular sections and sum their volumes.

Q3: What ACH should I use for different rooms?
A: Kitchens: 8-15, Bathrooms: 6-10, Workshops: 10-20, Living areas: 4-8. Higher for spaces with more pollutants or moisture.

Q4: Should I get a fan with higher CFM than calculated?
A: It's often good to round up to the nearest standard fan size, but avoid excessive CFM which can cause negative pressure issues.

Q5: Does duct length affect CFM requirements?
A: Yes, longer ducts with more elbows reduce effective CFM. Add 10-25% more CFM for long/complex duct runs.