In hydronic systems, what does the term “return water” refer to?

In hydronic systems, "return water" specifically refers to the water that has circulated through the heating spaces of a building and is returning to the boiler to be reheated. This water absorbs heat from the areas it serves; once it has delivered this heat, it cools down as it travels back to the boiler. The process of reheating is essential for maintaining an efficient and continuous heating cycle, ensuring that the system can effectively provide warmth to the spaces using the heated water.

While the water that goes to the boiler is an important part of the hydronic system, it is not referred to as return water. Also, irrigation water and discharged water do not play a role in the cyclical heating operation of a hydronic system, making those options less relevant to the terminology used in this context. Understanding the role of return water is crucial for anyone working with hydronic systems, as it directly impacts the efficiency and effectiveness of heating operations.