A measurement of the local Nusselt number of a confined circular air jet vertically impinging on a Aat plate is performed. The jet dow, after impingement, is constrained to exit in two opposite directions. Part of the impinging surface is maintained at a constant heat flux condition and the rest is adiabatic. The constant surface heat flux condition is modeled by conducting electricity through a thin stainless foil with a thickness of 0.01 mm. The heating foil was given constant heat flux values of 500, 1000, 1500 and 2000 W m(-2). Four diameters of the impinging jet 3, 4, 6 and 9 mm are considered individually. The jet Reynolds number is in the range of 30,000-67,000. The Hid is 2.0. The recirculation and mixing effect on the heal transfer is investigated by varying the jet diameter, surface heat dux, Reynolds number and surface heating width. The correlations of the local Nusselt number and the jet to-adiabatic wall temperature difference are obtained.