Numerical study of laminar, submerged impinging jets over a protruded, isothermal heat source is performed for a low range of Reynolds numbers (50 ≤ Re ≤ 250) and Prandtl numbers (0.71 ≤ Pr ≤ 7.56) to investigate some critical heat transfer characteristics in an unconfined domain. The height of the nozzle exit plane from the impingement surface is constant (h/W = 1). Two dynamically different zones of heat recirculation are shown to exist, one caused by the recirculating fluid flow near the sidewall and the other resulting from a larger thermal boundary layer interacting with entrained fluid when Pr < 1. The presence of a minimum threshold Pr value for any given Re is shown, which facilitates the onset of advection-dominant heat transfer from the heater sidewall. This transition is observed for lesser Pr values as Re is increased. Dimensionless heat flux distribution over the surfaces shows decrements with increasing Re and Pr, as a consequence of reduced characteristic velocity for an isothermal surface. Correlations have been obtained for the average heater surface and sidewall Nusselt numbers in terms of Re and Pr.