What is a cast iron boiler designed for?

A cast iron boiler is specifically designed to utilize the properties of cast iron to manage the gases of combustion effectively. In this type of boiler, the heated gases produced during the combustion process are directed around sections made of cast iron. This design maximizes the heat transfer to the water or steam that the boiler is generating, making it an efficient system for heating.

Cast iron is favored in these applications due to its excellent thermal conductivity and ability to withstand high temperatures and pressures, which are characteristic of the combustion process. Additionally, cast iron is known for its durability and resistance to corrosion, ensuring a long service life for the boiler.

In contrast to the other options, which describe different processes or materials that do not align with the fundamental purpose of a cast iron boiler, focusing on the flow of combustion gases highlights the specific operational design that enables the efficient heating of water or steam within the boiler system.