Water is continuously circulated in a closed stream through a plurality of vertically juxtaposed passages. Steam is introduced at the upstream ends of these passages and is drawn along the passages by the water so as to directly contact this water and condense. A restriction provided in each of the passages insures good condensation so that only gaseous noncondensable and nonsoluble portions of the incoming steam are drawn off at the downstream end of the passages where only the water is allowed to pass out.