If your heaters are like mine, which they sound like, Your 'set' control is the thermostatic control, ie : controlling how hot the radiator will get when charging.In milder weather you may only have it set at 1 or 2 and when colder, right up at 6. The other control has more to do with the radiator's capacity to store heat. The bricks that store the heat are in a sealed compartment inside the unit. If this compartment is kept closed the stored heat will last longer before the next charge. Your 'room temp' control simply opens and closes a flap on the top of this compartment, thereby allowing you to control how much heat is actually given out. Keeping it closed or set low, keeps the heat in for longer, opening it or turning up high releases stored heat more quickly to heat up you room. Hope this is of some help.