Hvac Design Calculations Excel Link

Where ΔT is the temperature difference between supply and return air (typically 20°F for cooling).

Flow Rate (GPM) = 24 * Q (Tons of Cooling) / ΔT (°F) hvac design calculations excel

=B2/(1.08*20) – assuming B2 holds the sensible heat load. 3. Duct Sizing (Equal Friction Method) Using the equal friction method (e.g., 0.08 to 0.12 in. w.g./100 ft), you can size ducts using a friction chart approximation. Where ΔT is the temperature difference between supply

CFM = Sensible Heat Load (Btu/hr) / (1.08 * ΔT) 0.08 to 0.12 in. w.g./100 ft)

Store a friction loss vs. CFM vs. diameter table. Use INDEX/MATCH or linear interpolation to find the nearest duct diameter for a given CFM at your target friction rate.