The equations and logic flow necessary to analyze a plate-fin heat exchanger are shown. Included are the heat transfer relationships in single-phase liquid or vapor and two-phase flow for refrigerants inside tubes, as well as an enthalpy analysis of the air-side for a typical HVAC coil. A simplified calculation flow chart shows how to set-up a computer program to perform the iterative calculations. Predicted exchanger performance is compared to experimental data for various plate-fin coils operated in the dry and wet modes.