The Series 81, Thermo-Z heat exchanger is designed to recover heat from energy consuming processes up to 1400°F (760°C). Energy can be recovered and used for process makeup air, plant or office heating, or preheated combustion air. The Thermo-Z is fully welded and has variable plate spacing on the heat exchanger supply and exhaust. With various flow patterns and zero cross contamination, it is both versatile and cost-effective. The internal casing is secured to a cold outer casing by means of integral thermal expansion joints. These joints allow the heat exchanger to be installed flange to flange to the ductwork without the need to compensate for thermal expansion of the heat exchanger.