<p>The condensation of water vapor from flue gas in the energy cycles of power and heating plants is an important issue to increase the efficiency of the boiler or to separate water vapor from flue gas. A theoretical study of flue gas condensation from biomass boilers in vertical tube condensers was conducted. An overview of the methods available for determining the condensation heat transfer coefficient was compiled. Three approaches were identified to determine the heat transfer coefficient and condenser heat output according to the foundation of each method: experimental foundation (Empirical correlations), semi-theoretical foundation (Heat and mass transfer analogy, Diffusion layer model) and theoretical foundation (Boundary layer model). Empirical correlations represent the simplest way to predict the condensation heat transfer coefficient. However, the deviation of the predicted results from the experimental results is quite high, and since the equations usually lack some important driving parameters or are developed for a slightly different geometry of operating conditions, they are not reliable enough for the considered application. The Boundary layer model is very complex and impractical. Therefore, the use of the Heat and mass transfer analogy or the Diffusion layer model is the most effective for the mentioned application.</p>