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Hot subdwarfs are helium burning objects in late stages of their evolution.These stars can develop winds driven by light absorption in the lines ofheavier elements. The wind strength depends on chemical composition which cansignificantly vary from star to star. We aim to understand the influence ofmetallicity on the strength of the winds of the hot hydrogen-rich subdwarfs HD49798 and BD+18$^\circ\,$2647. We used UV and optical spectra to derive stellarparameters and abundances. For derived stellar parameters, we predicted windstructure (including mass-loss rates and terminal velocities) with our METUJEcode. We derived effective temperature $T_\text{eff}=45\,900\,$K and mass$M=1.46\,M_\odot$ for HD 49798 and $T_\text{eff}=73\,000\,$K and$M=0.38\,M_\odot$ for BD+18$^\circ\,$2647. The abundances can be interpreted asa result of interplay between stellar evolution and diffusion. HD 49798 has astrong wind that does not allow for chemical separation and consequently itshows solar chemical composition modified by hydrogen burning. On the otherhand, we did not find any wind in BD+18$^\circ\,$2647 and its abundances aretherefore most likely affected by radiative diffusion. Accurate abundances donot lead to a significant modification of wind mass-loss rate for HD 49798,because the increase of the contribution of Fe and Ni to the radiative force iscompensated by the decrease of the force due to other elements. The resultingwind mass-loss rate $\dot M=2.1\times10^{-9}\,M_\odot\,\text{yr}^{-1}$ predictsan X-ray light curve during the eclipse which closely agrees with observations.On the other hand, the absence of the wind in BD+18$^\circ\,$2647 for accurateabundances is a result of its peculiar chemical composition. Wind models withaccurate abundances provide more reliable wind parameters, but the influence ofabundances on the wind parameters is limited in many cases.

Hot subdwarf wind models with accurate abundances I. Hydrogen dominated stars HD 49798 and BD+18$^\circ\,$2647