169. How does a convection oven work? How is it different from a regular oven?
In an electric convection oven, a fan circulates air rapidly through the cooking chamber. This rapid force circulation of air has two principal effects. First, it ensures that the temperatures throughout the oven are almost exactly equal. In a normal electric oven, the differences in temperatures that often occur lead to uneven cooking and require that you put the food in specific areas of those ovens to make sure that the food cooks properly. Since a convection oven has no temperature differences, you can put the food anywhere and you can fill the cooking chamber more completely with food. Second, a convection oven transfers heat more evenly to the food. By blowing hot air past the food, the oven prevents regions of colder air from building up near the surfaces of cool foods. Since the food in a convection oven is always in contact with hot air, it picks up heat faster and cooks faster. In a normal oven, heat is transferred to the food through normal convection (rising hot air and sinking cold air) and by radiation (particularly when the broiler is used). Both of these process are relatively slow and can be interrupted by over-filling the oven or blocking the line of sight between the hot filament and the colder food. In a convection oven, heat is transferred to the food mostly by forced convection (fan-driven hot air that circulates rapidly through the oven). This process is relatively fast and can't be interrupted by over-filling the oven (within reason) or blocking any line of sight between the hot filament and the food.