As I remember learning in school, heat cannot flow from cold to hot. But isn't that true only for conduction and convection? Radiation heat is purely Infrared waves, and there should not be any issue with that. Please correct if I am wrong.
Yes, so lets answer it:The OP is asking about radiant heat. Read his query.
Yes, so lets answer it:
Radiation between a cold and a hot object involves both objects radiating photons towards each other, but since the hot object is hotter, it radiates more (via the Stefan-Boltzman law) and the net energy transfer is from the hot object to the cold one. How much is determined by plugging both temperatures into the equation.