Why is upward flow of water in an economizer preferred?

The upward flow of water in an economizer is preferred primarily because it reduces the risk of water hammer. In systems where water is heated, the water is typically at a relatively low pressure before it enters the economizer. When this water flows upward, it allows any steam bubbles that may form to rise to the surface rather than getting trapped in the flow. If steam pockets accumulate, they can create sudden pressure fluctuations leading to water hammer, which might cause noise, damage to pipes, and increased wear and tear on equipment. Thus, managing the flow direction and ensuring that water travels upward helps to maintain steady and efficient operation, minimizing the likelihood of these damaging events.

While other factors such as heat absorption, steam pressure, and gas pressure might also be relevant in different contexts, they do not directly address the specific issue of water hammer that upward flow in an economizer is designed to mitigate.