Abstract: A unit to enhance heat transferring through a tube in a condenser-type heat exchanger comprises a series of elements. The elements engage a surface of the tube in contact with a high temperature condensable medium flowing through the exchanger. The elements are spaced apart, positioned parallel and have ring-like configurations. The elements are positioned on an angle so that when the unit is secured to a vertical tube, each element has a low point. These low points align and connect with a vertical riser. In use the tube is one of a set forming a tube bundle fitted into a vessel of the heat exchanger. As heat transfers from the high temperature medium, for example steam flowing through the vessel to a lower temperature medium, for example cooling water flowing through the tubes, the steam condenses on the tube. The condensed steam builds into a thickening film that then flows down the tube. This downward condensate flow is diverted by the elements of the unit and runs to the low point of each element.