The characteristics of the various parameters affecting the films and overall heat transfer coefficients of horizontal evaporator-condenser elliptical tubes are presented for a representative range of operating conditions. Effects of the axis ratio of the tube are analyzed and compared with the equivalent circular tube. The study indicates that the ratio of the vertical to the horizontal axis of about 4 approaches the asymptotic solution for a vertical plane of constant wall temperature and the average overall transfer rate decreases at axis ratios above 4. Effects of the intermittent removal of the condensate film from the wall are presented. The effect of homogeneously distributed noncondensables is accounted for.