A more technical explanation of heat transfer for those who may be interested: Heat is a form of energy. It exists in matter, but is not in and of itself matter. It doesn't weigh anything, so it evenly expands outwards in an attempt to equalize. The common misconception that heat rises comes from the fact that a warmer gas or fluid will be buoyant in the same gas or fluid at a lower temperature. This causes that gas or fluid to rise, carying its heat energy up with it. (Think hot air balloon) The important distinction here though is that it is not the heat energy that is buoyant, it's the gas or fluid itself which is buoyant.
