Folded Double Wall Heat Exchanger Tubes and Methods of Manufacture

A heat exchanger tube comprising:

• an inner wall;
• and
• an outer wall surrounding the inner wall,
• wherein the inner wall and the outer wall comprise a single sheet of material folded onto itself and forming a folded sheet of material, wherein the inner wall and the outer wall comprise a first plurality of ridges on a proximal end of the folded sheet and a second plurality of ridges on a distal end of the folded sheet, and
• wherein the inner wall and the outer wall are folded to form a top surface, a bottom surface, and side walls of the heat exchanger tube, and wherein the first plurality of ridges and the second plurality of ridges are folded such that the first plurality of ridges and the second plurality of ridges are disposed between the top surface and the bottom surface and form flow channels in the heat exchanger tube.

A water heater comprising:

• a water tank configured to store water;
• and
• a heat exchanger configured to receive a refrigerant and transfer heat from the refrigerant to the water stored in the water tank, wherein the heat exchanger comprises a heat exchanger tube, and wherein the heat exchanger tube comprises:
• an inner wall;
• and
• an outer wall surrounding the inner wall,
• wherein the inner wall and the outer wall comprise a single sheet of material folded onto itself and forming a folded sheet of material, wherein the inner wall and the outer wall comprise a first plurality of ridges on a proximal end of the folded sheet and a second plurality of ridges on a distal end of the folded sheet, and
• wherein the inner wall and the outer wall are folded to form a top surface, a bottom surface, and side walls of the heat exchanger tube, and wherein the first plurality of ridges and the second plurality of ridges are folded such that the first plurality of ridges and the second plurality of ridges are disposed between the top surface and the bottom surface and form flow channels in the heat exchanger tube.