Start with the mechanical system

Before you decide how a system should be controlled, establish what it is meant to do. A cooling system moves unwanted heat from one place to another. Its pipework, pumps, heat exchangers and valves form a physical system; the controller influences how that system operates.

Consider a simple water-based cooling circuit. Water passes through a heat exchanger, takes up heat and carries it to another part of the system where that heat can be rejected. A pump adds energy to circulate the water through the circuit. Pipework provides the route, and valves provide functions such as isolation or flow regulation, depending on their type.

Start a system review with three questions: What is the required outcome? Which components make that outcome possible? What operating conditions must be maintained? Answering these questions helps explain both the mechanical design and the eventual control strategy.