Basically there are two methods to determine thermal properties of soil: the linear source method and the cylindrical source method, both of them are based on approximated solutions in permanent regime to the problem of heat conduction from an infinitely lon of soil: the linear source method and the cylindrical source method, both of them are based on approximated solutions in permanent regime to the problem of heat conduction from an infinitely long source through an infinitely homogeneous medium. There are some minor differences in the implementation of both methods. The basic difference is that one of these is considered a linear thermal source and the other cylindrical. In this case the initial data must be discarded, because the approximations done to obtain the solution make the model very inaccurate in regard to the original behaviour. Also, both require that the heat transfer to the terrain must be kept constant at all times while the sampling process is performed, which can last 60 hours.