Abstract: A feed-water preheater for a steam power plant is disclosed. Feed-water at a relatively low temperature is conducted through bundles of heater tubes in heat exchange relation with steam from the turbine. The heater tubes are arranged in a U-shaped bundle, with one leg of the U serving as the cold inlet side and the other leg of the U serving as the warm outlet side of the heat exchanger. A partition extends lengthwise of the heater tubes between the legs and the U-shaped bundle. The steam inlet is located at the warm outlet side of the tubes and the housing forms a steam chest around the tubes. Deaerating pipes are provided on each side of the partition in the center of the bundle of heater tubes with openings spaced along the length of the deaerating pipes for receiving the noncondensable gases from the steam, and to draw off the gases through the deaerating pipes.