This research work shows different numerical schemes for 1D flow heat exchanger calculations based on Finite Volume Methods (FVM). The method allows calculating heat exchanger, flows in pipes, among other, where besides to appear pressure drops due to the flow field, a heat transfer can be presented with the environment, or another fluid. The general proposed method uses energy conservation, momentum conservation and mass conservation equations. Such equations are integrated throughout the heat exchanger, that along with the equations of state, and the equations that allow evaluating certain empirical parameters, constituting a system of nonlinear equations to solve. This paper describes a comparison of time consumption where sequential and simultaneous heat exchanger calculations are performed. The results show the most convenient calculation method obtained in this study that present the lowest error and time consumption is the sequential method when a constant wall temperature is assumed.