Transient and steady-state model response due to diabatic heating in the equatorial region is studied to gain insight of tropical circulations using two simple nonlinear numerical models. In the first part of this study, different heat sources are used to represent the continental areas of South America, Africa and Indonesia. The results show that the most dominant wave response arises from the Kelvin wave originating in the Indonesian region as the low-level eastward flow over the Pacific Ocean. This is a consequence of the Indonesian islands comprising the largest area of heating. In the second part of this study, different convective heat sources are placed over the eastern Pacific Intertropical convergence zone (ITCZ) and Panama bight. In these experiments, the model also includes realistic topography at a higher resolution than the first model. It is found that topography has only localized effects on the winds and geopotential height. Thus, the Caribbean low-level jet, which partially motivated these experiments, is yet to be explained. Also, when the position or intensity of the ITCZ changes, the large-scale winds in the Panama bight and the surrounding region change significantly, directly affecting large-scale circulations.