There are three distinct settings on the radiator above so if you place it on 600watts, I'm fairly certain it's not possible to go over and the 1500 watts might as well be a different heater. There's a second dial for the intensity of heat at the particular wattage selected so at halfway, I would assume it outputs ~300 watts. I could be mistaken on the effect the dial has on the wattage output but a VE-100 has a capacity of 700 watts which is greater than the max 600 watts of the heater regardless.