I forgot about the 100°C. If you put the thermometer inside the kettle inside the water, it should be at exactly 100°C, assuming 1atm of pressure, pure water a

I forgot about the 100°C. If you put the thermometer inside the kettle inside the water, it should be at exactly 100°C, assuming 1atm of pressure, pure water and and a few more technical details. Also, is you put the thermometer inside the kettle inside the vapor it should be at exactly 100°C, assuming 1atm of pressure, pure water and and a few more technical details. All those 100°C assume equilibrium or near equilibrium, so the very hot bottom of the kettle, the cold top, and the flowing stream may cause some problems. For some reason it's easier to visualize with water+ice instead of water+vapor, perhaps because it's easier to play with the mix. If you put water in the freezer, the temperature goes down to exactly 0°C, then it starts to freeze and both the water and the ice are at 0°C until you have a solid block of ice at 0°C and then, only then, the temperature continue to go down. The same happens in the oposite direction, from ice to liquid water. And the same happens with ice to vapor transition.