Yes as mongo alluded to, the wattage is controlled automatically while in TC mode. Some devices allow you to still set a max watts, while others will simply use whatever is available (all 40W on a 40W device, all 60 in a 60W, etc.) until the set temperature is achieved, and then they will dial down the wattage to maintain that temperature as long as the button remains pressed. The only difference the wattage setting should make in TC mode, when you're able to even change it at all, should be a faster/slower ramp up time before it reaches the temp limit.