The Steel plate heating boiler is classified as a _____ pass boiler.

A steel plate heating boiler is classified as a one-pass boiler because it is designed to have a single path through which the hot gases flow. In this configuration, the combustion gases pass through the boiler only once before being exhausted. This design is characteristic of many heating boilers, where the goal is to provide efficient heat transfer and straightforward operation.

One-pass boilers are often simpler in construction and require less maintenance compared to multi-pass boilers, as there are fewer components and potential points of failure. The single passage of combustion gases through the heat exchanger ensures that the heat is effectively transferred to the water or fluid being heated, providing reliable performance in a range of heating applications.

In contrast, multi-pass boilers, such as two-pass, three-pass, or four-pass designs, are built to optimize heat exchange by introducing additional pathways for the combustion gases. While these designs can improve efficiency and heat recovery, they also add complexity to the boiler's design and operation.