  Dots are ideal systems to study fundamentals on heat transfer at the
nanoscale and promising nanoscale heat-engines and thermal devices. Here, we
report on the validation of our theoretical model on the thermal conductance of
a metallic dot single-electron transistor (md-SET) by a recent experiment on
the low-T thermal conductance. We compare with the experiment, we emphasize the
physics interpretation and characteristic values and we apply the model to
evaluate the operation the md-SET as heat-switch. Perfect agreement is shown
between the calculated and the measured charge conductance G, heat conductance
\k{appa} and the ratio \k{appa}/GT. The experimental findings confirm the
theoretical predictions on the periodicity of the Coulomb oscillations in the
classical regime, the low-T extreme values and the high-T limits of G and
\k{appa}. The calculated conductances of the md-SET are presented in universal
curves from low-T to high-T. It is shown that the md-SET can efficiently
operate as a heat switch at temperatures , Ec being the charging energy of the
dot.
