I will analyze the probability distribution of the heat released by an ensemble of harmonic oscillators to the thermal bath, in the non-equilibrium relaxation process following a temperature quench. I will focus on the form taken by the Fluctuation Theorem and the number of oscillators is varied. After a detailed discussion of the case with one and two oscillators, I will consider the limit of a large number of oscillators, where condensation of the heat fluctuations occurs.