  We explain the physics of compressional heating of the deep interior of an
accreting white dwarf (WD) at accretion rates low enough so that the
accumulated hydrogen burns unstably and initiates a classical nova (CN). In
this limit, the WD core temperature (T_c) reaches an equilibrium value (T_c,eq)
after accreting an amount of mass much less than the WD's mass. Once this
equilibrium is reached, the compressional heating from within the envelope
exits the surface. This equilibrium yields useful relations between the WD
surface temperature, accretion rate and mass that can be employed to measure
accretion rates from observed WD effective temperatures, thus testing binary
evolution models for cataclysmic variables.
