The basic principle behind the operation of convection ovens is the flow of heat from the heating element through the conducting medium (the air) to the food. This differs from microwave or open flame cooking in that those sources of heat travel directly from the heat source to the food. The heated air that is circulated by the convection fan allows for a slower, more even cooking process. Every convection toaster oven, from a convection oven rotisserie toaster to a convection digital oven toaster works through this process. Convection microwave oven toasters switch mechanically between the two.
The best branded convection oven toasters have Quartz heating elements, preferably on the top and bottom, and a reflective crumb-tray. These features can speed up cooking time by 30% or more, depending on the oven’s wattage. It is also helpful if the heating element is of the “drop-down” type, which makes for easy cleaning.