Editing Convection oven (section)

== Design ==
A convection oven has a fan with a [[heating element]] around it. A small fan circulates the air in the cooking chamber.<ref>{{cite web|url=http://www.smeg.com/faq/ovens/what-s-the-difference-between-fan-and-fan-assisted-ovens/|archive-url=https://web.archive.org/web/20130507034832/http://www.smeg.com/faq/ovens/what-s-the-difference-between-fan-and-fan-assisted-ovens/|archive-date=2013-05-07|title=What's the difference between fan and convection ovens?|website=SMEG.com|access-date=20 July 2013}}</ref><ref>{{cite web|url=http://service.hoover.co.uk/advice-centre/built-in-appliances/ovens/troubleshooting/|title=Ovens Advice Centre|website=Hoover Advice Centre|access-date=20 July 2013|archive-url=https://web.archive.org/web/20130320183020/http://service.hoover.co.uk/advice-centre/built-in-appliances/ovens/troubleshooting/|archive-date=2013-03-20}}</ref>

One effect of the fan is to reduce the thickness of the stationary thermal [[boundary layer]] of cooler air that naturally forms around the food. The boundary layer acts as an insulator and slows the rate at which [[Heat transfer|heat is transferred]] to the food. By moving the cool air (''convecting'' it) away from the food the layer is thinned, and cooking is faster. To prevent overcooking before the middle is cooked, the temperature is usually reduced by about {{cvt|20|C-change|sigfig=2}} below the setting used for a non-fan oven. In a non-fan oven the temperature varies significantly in different places; a fan distributes hot air evenly for a uniform temperature.

Convection ovens may include additional [[radiant heat]] sources at the top and bottom of the oven, which provide immediate heat without the warmup time of a (natural or fan-assisted) convection oven.