  HR 4049 is a peculiar evolved binary which is surrounded by a circumbinary
disk. Mid-infrared observations show that the disk is rich in molecular gas and
radially extended. To study the properties of this disk, we re-analyzed a set
of near-infrared observations at high spectral resolution obtained with
Gemini-Phoenix. These data cover absorption lines originating from the first
overtone of CO and from \hoh in the 2.3 $\mu$m region as well as more complex
emission-absorption profiles from \hoh and the fundamental mode of CO near 4.6
$\mu$m. By using an excitation diagram and from modeling the spectrum, we find
that most of the CO overtone and \hoh absorption originates from hot gas
($T_{\rm ex} \approx 1000$~K) with high column densities, consistent with the
mid-infrared data. The strong emission in the wavelength range of the CO
fundamental furthermore suggests that there is a significant quantity of gas in
the inner cavity of the disk. In addition, there is a much colder component in
the line of sight to the disk. A detailed analysis of the overtone line
profiles reveals variations in the line widths which are consistent with a
radially extended disk in Keplerian rotation with hotter gas closer to the
central star. We estimate the mass of the primary to be $\sim 0.34$~M$_{\odot}$
and discuss the implications for its evolutionary status.
