The water flow through a modular cast iron boiler system:

In a modular cast iron boiler system, the water flow is designed to be continuous through all modules. This continuous flow is essential for maintaining a consistent temperature and ensuring that the heating system operates efficiently and effectively. A continuous flow allows for better heat transfer within each module, which enhances the overall performance and responsiveness of the boiler system. By having water circulate continuously, it helps to stabilize the operation during various heating demands, preventing fluctuations that could lead to inefficiencies or operational issues.

Other options do not align with how these systems are designed to function. For instance, not using headers or manifolds would restrict the flow and management of water throughout interconnected modules. Intermittent flow would result in inconsistent heating and could lead to overheating or lack of heat during no-firing periods. Connecting modules in series would limit the performance and flexibility of the system, as each module would only be able to operate based on the previous module’s output and would not allow for the optimal flow dynamics that a continuous setup provides.