The main reason it takes much longer for an oven to preheat compared to a toaster is due to differences in their heating elements and the amount of space they need to heat.
Heating Element Size and Power: Toaster ovens typically have smaller heating elements compared to conventional ovens. The smaller heating elements in a toaster oven heat up quickly because they have lower thermal mass and require less energy to reach the desired temperature. In contrast, conventional ovens have larger heating elements spread throughout a larger oven cavity, and it takes more time and energy to heat up the entire space.
Oven Cavity Size: Toaster ovens have a smaller internal cavity than conventional ovens. This smaller space means that there is less air and mass to heat up, making it quicker for the toaster oven to reach the set temperature. Conventional ovens, on the other hand, have a larger interior volume, which requires more time and energy to heat up all the air and surfaces inside.
Insulation: Conventional ovens are designed with more substantial insulation to retain heat efficiently and maintain a consistent temperature during cooking. This level of insulation slows down both the heating and cooling processes. Toaster ovens generally have less insulation since they are meant for shorter cooking times, and this helps them heat up faster.
Temperature Control: Conventional ovens often have more precise temperature control and need to be accurate in maintaining the set temperature throughout the cooking process. To achieve this precision, they may take additional time to preheat. Toaster ovens may have simpler temperature control mechanisms, which can allow them to heat up more quickly.
In summary, the combination of smaller heating elements, a smaller oven cavity, and potentially less insulation in a toaster oven allows it to preheat much faster than a larger conventional oven. However, the trade-off is that toaster ovens have limitations in terms of the amount of food they can cook at once and may not offer the same level of temperature control and consistency as larger ovens designed for more extensive cooking tasks.