Typically, when food is cooked in a conventional oven it cooks unevenly, often getting too hot on the bottom and not hot enough on the top because of the placement of the heating element. If the oven has a lot of food in it, especially if there are multiple racks in place, the food on the top rack will bake at a much different speed from the food on the lower rack. Food may need to be rearranged periodically during the cooking process for even baking. A single fan oven, also called a convection oven, solves this problem by using the fan to move the hot air around inside the oven, providing for more even cooking. This type of oven is commonly in use in restaurants, and many at home find that they enjoy the performance of a convection oven as well.
When hot air is circulated in a single fan oven, the heat can no longer get trapped in one area and instead is distributed much more evenly. Food is cooked in a more consistent manner and baking time may be shortened, resulting in potentially significant energy savings. This tends to be especially noticeable in homes that use electricity for cooking, especially if the oven is used often.
Such ovens are not commonly installed in homes, but many people choose to upgrade to either a single fan oven or a double fan oven at some point. There are many different models to choose from, and include a wide range of choices from counter top models to built-in units that replace the existing oven. For those that want the features of a single fan oven without a lot of expense there are small, round, portable ovens, often called wave ovens, that use a combination of convection cooking, radiant heat, and infrared or halogen technology.
It is very common for a single fan oven to be able to be used with or without the fan in operation. This allows the cook to make the choice as to what he or she feels is the best method of cooking for the particular food or dish. It is generally quite easy to switch back and forth between convection and non-convection cooking by setting a switch on the oven.