Top: ratio between the measured integrated intensities and the LVG model predictions. Filled circles/triangles depict o-H₂O and p-H₂O lines, respectively. In black, we display the results assuming one single temperature component (T_kin = 250 K, n(H₂) = 10⁶ cm^-3, N(o-H₂O) = 2 × 10¹⁴ cm^-2, size = 10′′); in red, the final solution when adding the contribution of the second temperature (T_kin = 1000 K, n(H₂) = 2 × 10⁴ cm^-3, N(o-H₂O) = 7 × 10¹⁶ cm^-2, size = ). Bottom: predicted CO fluxes from the hot component, as a function of the rotational upper level in the HIFI and PACS range. The observed fluxes (Benedettini et al. 2012; Lefloch et al. 2012) are marked with filled circles. The choice of [CO]/[H₂O] = 1 provides an upper limit estimate of the CO integrated intensity (see Sect. 4.2.3 for more details).