What is one common way air enters the steam jacket of a kettle?

Air commonly enters the steam jacket of a kettle via leaks in various fittings. This occurs because the steam jacket is designed to maintain a specific environment within the kettle for efficient heating. If there are worn or damaged gaskets, seals, or connections, air can infiltrate the system, compromising the steam pressure and thermal efficiency. Maintaining integrity in these fittings is crucial to ensuring that the steam jacket remains airtight, which allows for effective heating and prevents energy loss.

While temperature fluctuations can cause expansion and contraction, leading to minor pressure changes, they do not directly introduce air into the jacket. Overfilling the kettle can lead to water entering the steam jacket, but it doesn’t necessarily result in air infiltration. Lastly, though the outside environment could potentially impact the kettle's operation, it is not a common mechanism for introducing air into the steam jacket itself compared to leaks in the fittings.