Cfm Per Btu Calculator

CFM Per BTU Formula:

\[ CFM = \frac{BTU/h}{1.08 \times \Delta T} \]

Air Flow (CFM):

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1. What is CFM Per BTU?

CFM (Cubic Feet per Minute) per BTU is a measurement used in HVAC systems to determine the air flow rate required to transfer a specific amount of heat energy. It helps in sizing ductwork and selecting appropriate HVAC equipment for efficient thermal management.

2. How Does the Calculator Work?

The calculator uses the CFM per BTU formula:

\[ CFM = \frac{BTU/h}{1.08 \times \Delta T} \]

Where:

\( CFM \) — Cubic Feet per Minute (air flow rate)
\( BTU/h \) — British Thermal Units per hour (heat transfer rate)
\( 1.08 \) — Constant factor for standard air conditions
\( \Delta T \) — Temperature difference in degrees Fahrenheit

Explanation: The formula calculates the air flow required to transfer a given amount of heat energy based on the temperature difference between supply and return air.

3. Importance of CFM Calculation

Details: Accurate CFM calculation is essential for proper HVAC system design, ensuring efficient heat transfer, maintaining comfort levels, and optimizing energy consumption in heating and cooling applications.

4. Using the Calculator

Tips: Enter BTU/h value (heat transfer rate) and temperature difference in °F. Both values must be positive numbers for accurate calculation results.

5. Frequently Asked Questions (FAQ)

Q1: What does the 1.08 constant represent?
A: The 1.08 constant accounts for the specific heat of air (0.24 BTU/lb-°F) and air density (0.075 lb/ft³) at standard conditions, converted to appropriate units.

Q2: When is this calculation typically used?
A: This calculation is commonly used in HVAC system design for sizing ductwork, selecting fans, and determining air flow requirements for heating and cooling systems.

Q3: What are typical CFM values for residential systems?
A: Residential HVAC systems typically range from 400-2000 CFM depending on the home size, with average values around 1000-1500 CFM for standard single-family homes.

Q4: Does altitude affect the calculation?
A: Yes, at higher altitudes, air density decreases, which may require adjustments to the constant factor for accurate calculations.

Q5: Can this formula be used for both heating and cooling?
A: Yes, the formula works for both heating and cooling applications, as it calculates air flow based on heat transfer requirements regardless of direction.