A feedwater heater for use in a power plant system in which steam from another unit in the system is introduced into the shell of the heater and the latter discharges condensate to another unit in the system. Feedwater to be heated is circulated through tubes in the shell in heat exchange relation to the steam whereby a portion of the steam is condensed. Another portion of the steam is directed to an area of the shell where it warms the condensate to a degree that maintains the condensate at or near its saturation temperature. An additional inlet is provided in the shell for receiving condensate from another unit of the system along with means for breaking up the flow of the latter condensate to promote deaeration as a portion of the condensate flashes into vapor. The vapor produced as a result of the flashing is directed in the same flow path as the above-mentioned steam, and vent means are provided for permitting the removal of the non-condensibles and associated water vapor from the shell.