Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2007)
Convection ovens or fan ovens or turbo ovens augment a traditional oven by circulating heated air using a fan. The fan motor is in a separate enclosure, to protect it from overheating and melting any plastic components including wire insulation. Food warms faster in a convection oven, because the moving air strips away the thin layer of air which otherwise would surround and insulate the food. This is the same physical phenomenon which causes wind chill.
By moving fast hot air past the food, convection ovens can operate at a lower temperature than a standard conventional oven and yet cook food more quickly. The air circulation, or convection, tends to eliminate "hot spots" and thus food may bake more evenly.
An impingement pizza oven at a Hungry Howie's store in Auburn, Alabama
A convection oven will have about a 50 degree Fahrenheit (30 degree Celsius) reduction in cooking temperature, compared to a conventional oven. This comparison will vary, depending on factors including, for example, how much food is being cooked at once or if airflow is being restricted by using an over sized baking tray. This difference in cooking temperature is offset by the fact that circulating air transfers heat more quickly than still air of the same temperature; in order to transfer the same amount of heat in the same time, then, one must lower the temperature to reduce the rate of heat transfer to compensate.
The word convection actually refers to the natural circulation such as that caused by temperature differences and all ovens have these natural convection currents that vary with food placement and the position of the heating elements. Thus, strictly speaking, it is a bit of a misnomer to refer to an oven where the circulation is forced by a fan as a "convection oven" however one might construe the name to be a shortening of "forced convection oven."
Many convection ovens also include a proofing capability using the same fan but at a much lower temperature. A residential double oven will often include the fan capability in only one of the two ovens.
Convection microwave ovens combine a convection oven with a microwave oven to cook food with the speed of a microwave oven and the browning ability of a convection oven.
Another form of a convection oven is the commercial impingement oven. This type of oven is often used to cook pizzas in restaurants. Impingement ovens have a high flow rate of hot air from both above and below the food. The air flow is directed onto food which usually passes through the oven on a conveyor belt. Air flow rates can range between 1-5 m/s. Impingement ovens can achieve a much higher heat transfer than a conventional oven.
Like the "impingement oven" a convection oven usually has the radiant elements in view of the food, which improves heat transfer and speeds cooking from initial cold start. Some ovens have the heating elements placed in an outside enclosure and hidden from the food. This eliminates radiant heat from direct contact with the food.
Description of convection ovens from Wolf Range, Inc. (see page 5)
Convection Oven Recipe Converter.
Choosing a Halogen Oven (a portable form of convection oven).
Categories: Cooking appliances | ConvectionHidden categories: Articles lacking sources from December 2007 | All articles lacking sources | All articles with unsourced statements | Articles with unsourced statements from December 2007