Results from the previous work of Strouhal et al. (2020) suggest that the used CFD fouling model together with user-implemented subroutines is not sufficient for obtaining satisfactory agreement with deposits observed in a described experimental device. The objective of this work is to create a basis for qualitative improvements of the simulation results. This includes using more detailed geometry and testing an influence of variation of parameters of two implemented fouling models. An accurate estimation of these parameters requires either empirical evidence from device operation or detailed information about fly ash composition and properties, which is usually accessible only for individual fly ash constituents. The goal of the sensitivity analysis was to show influence of these parameters on deposition rates, identify insignificant parameters for the tested range of particle properties and diameters and the most significant parameters for each of the six tested fly ash size fractions. To the authors’ knowledge, such an analysis is not present in available literature. The first tested model shown that one parameter to be significantly higher compared to other, except for the smallest particles. For the second model, all parameters were found to be significant at least for one examined particle diameter. Elastic deformation, plastic deformation and adhesion are thus considered important across the tested range of particle properties and sizes, at least for the fouling model used.