Heat exchanger

A heat exchanger that withstands 3000 psi of hot water pressure at 180° F. (82.2° C.), the heat exchanger comprising:

• an outer tube having a water inlet for receiving cold water therein and a hot water outlet for producing hot water therefrom;
• an intermediate tube inserted into the outer tube to form a chamber therebetween;
• an inner tube inserted into the intermediate tube and having a heat inlet therein;
• a transition section having a tubular cylindrical portion positioned at one end of the outer tube, the intermediate tube, and the inner tube and a domed portion positioned on the tubular cylindrical portion with the tubular cylindrical portion and the domed portion having an interior in fluid communication with the chamber;
• an insulator covering the transition section domed portion, at least partially;
• an interior sheet positioned around the outer tube for sealing gases therein;
• an exterior sheet positioned around the interior sheet that includes insulating material therein;
• wherein a plurality of dividers is positioned between the outer tube and the intermediate tube, so that the chamber is divided into at least two divisions with each division being in fluid communication with the transition section interior, so that cold water flows into the water inlet, circulates from one of the divisions to the second division through the transition section interior, receives heat from the inner tube to transform the cold water into hot water, flows from the second division and out of the hot water outlet.