A radiator and radiant heat are not the same. one is a scientific term the other is type of heater that actually uses convection heating.

Again the same point remains UTH type heaters don't heat air well. If they did they would dramatically change the relative humidity and they don't. Racks primary rely on the room temp for the background temp. There is little provision to add a secondary heater in a off the shelf unit it takes a custom designed and build rack to add something like a tube heater.