The invention relates to an assembly comprising a vacuum pump and a chamber, wherein a suction tract extends between the chamber and the vacuum pump. The vacuum pump is a liquid ring machine. According to the invention, a liquid outlet is arranged in the suction tract in order to add liquid to gas sucked in from the chamber. The invention further relates to a method for evacuating a chamber filled with vapor. According to the invention, the vapor is condensed by introducing additional liquid into the suction tract, thus by co-condensation. By supplying liquid selectively only when liquid is required for the condensation of the vapor, water is saved.