If a kettle is up to pressure but not cooking, what is a likely issue?

When a kettle is up to pressure but not cooking, the presence of air in the kettle is a likely issue because air pockets can disrupt the even distribution of heat throughout the water. Steam cooking relies on the transfer of heat from the steam to the food and, if air is trapped, it can act as an insulator, preventing the necessary heat from reaching the water and thus cooking effectively.

In a properly functioning steam kettle, the steam should continuously circulate around the food and maintain a consistent cooking temperature. If air is present, it prevents the steam from coming into contact with the food, causing an inefficient cooking process despite the kettle being pressurized. Addressing air pockets typically involves purging the system to ensure that only steam is present, allowing for proper cooking conditions.