Influence of our four free parameters on synthetic Herschel/HIFI profiles in the ortho-H₂O fundamental line 1₁₀–1₀₁ at 557 GHz (top row) and the 3₁₂–2₂₁ line at 1153 GHz (bottom row). The reference profile (S0 model with = 25 AU and i = 60°) is plotted in red, and other colors show the effect of changing one of the parameters. From left to right: (panels a)–b)), accretion rate (panels c), d)), M_⋆ (panels e), f)), inclination angle i to the line of sight (panels g), h)). Only the blueshifted lobe is shown, except in panels g), h) where red and blue lobes have been summed. The distance to the source is set to 235 pc.