  Mesoscopic superconductivity deals with various quasiparticle excitation
modes, only one of them -- the charge-mode -- being directly accessible for
conductance measurements due to the imbalance in populations of quasi-electron
and quasihole excitation branches. Other modes carrying heat or even spin,
valley etc. currents populate the branches equally and are charge-neutral,
which makes them much harder to control. This noticeable gap in the
experimental studies of mesoscopic non-equilibrium superconductivity can be
filled by going beyond the conventional DC transport measurements and
exploiting spontaneous current fluctuations. Here, we perform such an
experiment and investigate the transport of heat in an open hybrid device based
on a superconductor proximitized InAs nanowire. Using shot noise measurements,
we investigate sub-gap Andreev heat guiding along the superconducting interface
and fully characterize it in terms of the thermal conductance on the order of
$G_\mathrm{th}\sim e^2/h$, tunable by a back gate voltage. Understanding of the
heat-mode also uncovers its implicit signatures in the non-local charge
transport. Our experiments open a direct pathway to probe generic
charge-neutral excitations in superconducting hybrids.
