Final answer:
In home economics, preheating dogs in a boiler is not a cooking practice. Preheating times for ovens and boilers vary depending on the specific appliance and desired temperature.
Step-by-step explanation:
In the context of home economics, preheating dogs in a boiler is not a cooking practice. It seems there may be some confusion or a typo in the question. However, if you are referring to preheating ovens or boilers in general, the time required can vary depending on the specific appliance and the desired temperature.
For example, if we consider preheating an oven, it typically takes about 10-15 minutes for most household ovens to reach a temperature of 350°F (175°C). However, larger commercial ovens or industrial boilers may take longer to preheat due to their size and power.
It is important to refer to the specific manufacturer's instructions for the appliance in question to get accurate preheating times and temperatures.