  We report a calculation of all two-loop QED corrections with closed fermion
loops for the n=1 and n=2 states of H-like ions and for a wide range of the
nuclear charge numbers Z=1-100. The calculation is performed to all orders in
the binding-strength parameter (Z \alpha), with the exception that in a few
cases the free-loop approximation is employed in the treatment of the fermion
loops. Detailed comparison is made with previous (Z \alpha)-expansion
calculations and the higher-order remainder term to order \alpha^2 (Z \alpha)^6
is identified.
