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CFM Formula:
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The BTU/h to CFM conversion calculates the required airflow (in cubic feet per minute) needed to handle a specific heat load (in British Thermal Units per hour) given a temperature difference. This is essential for HVAC system design and sizing.
The calculator uses the standard HVAC formula:
Where:
Explanation: The formula calculates the airflow required to remove or add heat based on the heat load and desired temperature change.
Details: Proper airflow calculation is crucial for designing efficient HVAC systems, ensuring adequate ventilation, maintaining comfort levels, and optimizing energy consumption in residential, commercial, and industrial applications.
Tips: Enter heat load in BTU/hr and temperature difference in °F. Both values must be positive numbers. The calculator will determine the required airflow in CFM for your specific heating or cooling application.
Q1: What is the 1.08 constant in the formula?
A: The 1.08 constant is derived from the density of air (0.075 lb/ft³), specific heat of air (0.24 BTU/lb·°F), and conversion from hours to minutes (60 min/hr).
Q2: When is this calculation typically used?
A: This calculation is commonly used in HVAC design for sizing air handlers, ductwork, and ventilation systems for both heating and cooling applications.
Q3: What are typical CFM requirements?
A: Typical CFM requirements vary by application: residential rooms (50-150 CFM), commercial spaces (200-2000 CFM), industrial areas (1000-10,000+ CFM) depending on heat load and temperature requirements.
Q4: Does this work for both heating and cooling?
A: Yes, the formula works for both heating and cooling applications. For heating, ΔT is positive (supply air warmer than room air). For cooling, ΔT is negative but use absolute value in calculations.
Q5: What factors affect airflow requirements?
A: Factors include building insulation, occupancy, equipment heat loads, climate conditions, desired temperature differentials, and specific application requirements.