Abstract: A coiled heat exchanger and a method of making a coiled heat exchanger including a pair of sheets coiled together to form a core having opposite faces. A first sheet has at least one edge extending substantially coplanar with the sheet. A second sheet has at least one edge having alternating portions along the edge being respectively raised and unraised with respect to the plane of the sheet such that when the sheets are coiled together the at least one edge of the second sheet is configured to abut portions of the at least one edge of the first sheet at locations corresponding to the alternating raised portions. These edges and their alternately abutting portions form openings in the form of angular sectors on a face of the core that are configured to pass fluid therethrough.