For those that are wondering this analysis of radiation from a panel radiators,ompared to the makers rating suggests about 20-25% of the heat from a domestic rad is actually radiated ( In the stefan-bolzman 4th power of absolute temperature way) from one surface, and the rest is presumably a mix of what is convected and the radiation off the back heating the wall to some temperature between that of the room and the hot water. Not negligible, but certainly not the dominant effect.
For those that are wondering this analysis of radiation from a panel radiators,ompared to the makers rating suggests about 20-25% of the heat from a domestic rad is actually radiated ( In the stefan-bolzman 4th power of absolute temperature way) from one surface, and the rest is presumably a mix of what is convected and the radiation off the back heating the wall to some temperature between that of the room and the hot water. Not negligible, but certainly not the dominant effect.
