Two decades ago it was made the first steps to establish a really Hamiltonian description of field theory of dissipative transport processes in order to apply all of the tools of modern field theories for these kind of processes. The great breakthrough was to introduce such scalar potential fields for the measurable quantities-temperature, pressure, etc.-, by which the complete Lagrangian-Hamiltonian formalism could be developed. Later it has been managed to create the differential equation for the relativistic invariant heat propagation by the help of the scalar field, which field can generate a dynamical temperature immediately. In the present paper it is focused on a farther step in the Lorentz invariant thermal energy propagation. Now, the temperature field satisfies a covariant field equation of a (wave-like) thermal energy propagation with finite speed-less than the speed of light. In our previous works the connection has been clarified between this scalar field and the usual local equilibrium temperature including the classical Fourier's heat conduction. The existence of a dynamical phase transition between the two kinds of propagation, between a wave and a non-wave, i.e., a dynamical phase transition between a non-dissipative and a dissipative thermal process is also found. Presently, it is pointed out that the so-called Wheeler propagator can be obtained without any difficulty for this process inspite of the existence of the dynamical phase transition and it can be seen that the causality condition is completed at the same time.