Duct Heat Gain/Loss Calculator

Calculate heat gain or loss through duct walls in unconditioned spaces. Critical for maintaining supply air temperature and system efficiency.

Volume flow rate through the duct.
CFM
Length of duct in unconditioned space.
feet
Width of rectangular duct.
inches
Height of rectangular duct.
inches
Thermal resistance of duct insulation.
hr·ft²·°F/BTU
Temperature of air inside the duct.
°F
Temperature of space surrounding the duct.
°F

Results

Duct Surface Area-ft²
Heat Transfer Rate-BTU/hr
Air Temperature Change-°F
Final Air Temperature-°F
References: ASHRAE Fundamentals Chapter 23: Insulation for Mechanical Systems; ASHRAE Handbook - HVAC Systems and Equipment