A heat exchanger fabricated from a plurality of plates arranged in spaced parallel relation with one another as a stack or assembly that is positioned between pressure plates. The stack of plates are arranged to define fluid and vapor passages with the entire assembly, including cover members, being held together by suitable clamp plates. A flow control element is positioned in the exchanger to control the flow of the incoming liquid, as well as any recirculating liquid, in the delivery of said liquid to the boiling passages.