According to what I remember reading in the reports on the tests in the times when these were being sold, the control was vastly oversold. They were in no way automatic like the Coffeemaster, but required attention from the user up until the heat was turned down, but the user had to deal with the amount of heat built up in the firebrick to know when to turn it down so it was a learning experience. I can tell you that when we used a percolator on an open coil stove, when the perking first started, my mother would shut off the heat and the coffee would perk for 8 to 10 minutes on the stored heat. Naturally, the wattage of the heater would figure into this. Maybe JeffAdelphi, who played with these pots a lot, might remember using this control and could tell about it.