Why can’t I get water to boil in an oven at 180 degrees?

Answer

Dear Jan,

We will assume that it is effectively 180°C inside the oven (so there is no problem with the temperature sensor, the oven has been on for a while, etc.).

For many of us, ‘boiling’ means seeing bubbles at the bottom of a cooking pot, the water bubbling and water vapor coming out of the pot. I imagine you don’t see that happening in the oven.

When a pot is on the fire, all the heat comes from below, and the surroundings are cold. The water will therefore start to boil at the bottom of the pot: bubbles of water vapor will be formed, which will bubble upwards. When the water vapor leaves the pot, it enters the colder environment. As it cools down, the water begins to condense, just like in clouds, and we see the “vapour.”

In an oven, however, the heat comes from everywhere. So the water in the pot will start to evaporate from the surface of the water, and not from the bottom. That’s why we don’t see bubbles. When the water has evaporated, it remains a gas and it will not condense, because the whole environment is warm. That’s why we don’t see the vapor coming out of the pot.

If you put a liter of water in the oven and wait an hour, the water should (almost) disappear: that is proof that it is indeed boiling.