We revisit Cattaneo's derivation of the equation describing heat transfer and bearing his name, finding a more elaborated model equation, that we will compare with the time-lagged model. This equation does not comply with the second law of thermodynamics, as well as Cattaneo equation. The latter, however, is known to have provided meaningful results in certain experiments conducted in some liquids and solids at very low temperature. These experiments also match the results given by a nonlinear model proposed by A. Morro and T. Ruggeri in 1988, which instead does meet the laws of thermodynamics. A comparison is made with such a model too. KEYWORDS Cattaneo-Maxwell-Vernotte equation, heat equation, heat transfer, heat waves, second sound, thermal lag MSC CLASSIFICATION 80A20 Math Meth Appl Sci. 2020;43:5953-5962.wileyonlinelibrary.com/journal/mma