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GPM Formula:
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The BTU/hr to GPM conversion calculates the flow rate in gallons per minute (GPM) required to transfer a specific amount of heat energy (BTU/hr) with a given temperature difference (ΔT). This is commonly used in HVAC and hydronic heating systems.
The calculator uses the formula:
Where:
Explanation: The formula calculates the flow rate needed to transfer the specified heat energy with the given temperature difference in a water-based system.
Details: Accurate flow rate calculation is essential for proper system design, ensuring adequate heat transfer, preventing equipment damage, and optimizing energy efficiency in heating and cooling systems.
Tips: Enter BTU/hr value (heat transfer rate) and temperature difference in °F. Both values must be positive numbers. The calculator will determine the required flow rate in gallons per minute.
Q1: Why is the constant 500 used in the formula?
A: The constant 500 is derived from the specific heat of water (1 BTU/lb·°F), water density (8.34 lb/gal), and time conversion (60 min/hr): 1 × 8.34 × 60 ≈ 500.
Q2: Can this formula be used for other fluids?
A: This specific formula is designed for water. For other fluids, you would need to adjust the constant based on the fluid's specific heat and density.
Q3: What is a typical ΔT value for hydronic systems?
A: Most hydronic heating systems are designed with a ΔT of 20°F, though this can vary based on system design and requirements.
Q4: How does flow rate affect system performance?
A: Insufficient flow can lead to poor heat transfer and system inefficiency, while excessive flow can cause noise, erosion, and increased pump energy consumption.
Q5: Is this calculation applicable to both heating and cooling systems?
A: Yes, the same principle applies to both heating and cooling applications, though the direction of heat transfer is different.