Equator and tropics

If the equator and tropics never have negative Average Clear-sky Net Radiation values then they are always gaining heat.  Theoretically this means they should get dramatically hotter and hotter year after year but this clearly isn’t happening.  Likewise the average flux values for the poles are negative; they are losing heat yet they are not getting colder and colder.  Where must all the surplus heat from the equator and tropics go and how does it get there?