  Isotopes with low-lying long-lived isomers can behave very differently from
other isotopes in astrophysical environments. In particular, the assumption of
thermal equilibrium in computing the temperature-dependent $\beta$-decay rates
of such isotopes can fail below certain temperatures. We focus on the
$\beta$-decay of $^{26}$Al since it is one of the most important isotopes in
observational astrophysics and has a low-lying isomeric state; we compare and
contrast these results with $^{34}$Cl. We rule out recently reported $^{26}$Al
effective $\beta$-decay rates that showed large differences from previous
calculations, finding that we agree with the earlier results. We conclude that
in general, effective $\beta$-decay rates should be defined separately for the
ground and isomeric states at temperatures where thermal equilibrium cannot be
achieved.
