  Leung, Chan & Chu (2004) claimed that a previously neglected reheating effect
makes a small but noticeable change to the process of cosmological
recombination. We revisit this effect by considering a system consisting of
both radiation and ionizing gas under adiabatic expansion. In the thermal
equilibrium limit, due to the huge radiation background, only a fraction about
10^-10 of the heat released from the recombination of atoms is shared by the
matter. And in the standard hydrogen recombination calculation, the maximum
fraction of energy lost by the distortion photons through multiple Compton
scattering is certainly less than 10^-3. Thus this effect is negligible.
