The furnace heat exchanger project included the design, construction, presentation, and eventual testing of a device which simulates flue gas within the tubes of a secondary heat exchanger in a typical residential furnace. After the design is certified, the apparatus will then be used to confirm results of a CFD study being conducted in conjunction with the senior design project. The tube has a turbulator inserted to create a turbulent and indirect flow through the inner passage. This turbulence forces fluid interactions with the outside of the tube, which increases the heat transfer coefficient between the fluid and the inner tube surface. Measuring the temperature gradients along the tube surface will help validate the computational analysis of the fluid flow within the tubes. This computational analysis will then predict/confirm the energy content of the simulated flue gases as it exchanges heat with the tube walls. Although the simulated flue gas is not an entirely accurate replication of flue gases in an actual heat exchanger, the difference is considered negligible in this application.