1. What is CFM Calculation Based on BTU?

The CFM (Cubic Feet per Minute) calculation based on BTU (British Thermal Units) is used in HVAC systems to determine the airflow required to meet specific heating or cooling loads. This calculation helps in proper HVAC system sizing and efficient operation.

2. How Does the Calculator Work?

The calculator uses the CFM formula:

Where:

• \( CFM \) — Cubic Feet per Minute (ft³/min)
• \( BTU \) — Heating load in British Thermal Units per hour
• \( 1.08 \) — Air factor constant
• \( \Delta T \) — Temperature difference between supply and return air in °F

Explanation: The formula calculates the airflow required to transfer the specified amount of heat energy, considering the temperature difference and the specific heat capacity of air.

3. Importance of CFM Calculation

Details: Accurate CFM calculation is essential for proper HVAC system design, ensuring adequate heating/cooling capacity, energy efficiency, and occupant comfort. Incorrect CFM can lead to poor performance and increased energy costs.

4. Using the Calculator

Tips: Enter BTU value in BTU per hour and temperature difference in °F. Both values must be positive numbers. The calculator will determine the required CFM for your HVAC system.

5. Frequently Asked Questions (FAQ)

Q1: What is the 1.08 constant in the formula?
A: The 1.08 constant represents the specific heat of air (0.24 BTU/lb·°F) multiplied by the density of air (0.075 lb/ft³) and converted to minutes (60 min/hour).

Q2: What is a typical ΔT value for HVAC systems?
A: Typical ΔT values range from 15-25°F for heating systems and 18-22°F for cooling systems, depending on the specific application and design.

Q3: How does CFM affect HVAC system performance?
A: Proper CFM ensures efficient heat transfer, maintains desired temperatures, prevents short cycling, and extends equipment lifespan.

Q4: Can this formula be used for both heating and cooling?
A: Yes, the formula works for both heating and cooling applications, though the ΔT values and system considerations may differ.

Q5: What factors can affect CFM requirements?
A: Room size, insulation quality, window area, occupancy, equipment heat loads, and climate conditions all influence CFM requirements.