A tube for use in a heat exchanger includes an upper portion, a base portion spaced from the upper portion, and a partitioning wall depending from the upper portion. The partitioning wall is bent away and spaced from the base portion in a first section of the tube to form a single flow channel within the tube along the first section. The partitioning wall contacts the base portion in a second section of the tube to form a partition separating a first flow channel from a second flow channel along the second section. The first section of the tube is configured for reception into an opening of a header tank of the heat exchanger.