In this paper a Low-Mach number approximation of the Navier Stokes Equations in unstructured meshes is presented. Both staggered and collocated formulations for unstructured grids will be used.The aim is to develop a numerical algorithm suitable for describing flows which present large variations of the density field, but that the speed of the flow is low, so that the Mach number is small and if a compressible formulation was to be used would cause strong limitations to the time step. The test case for verification will be a differentially heated cavity with a large temperature gradient. The results will be compared against benchmark data.