In many hydronic systems, there’s a need to divide the overall system flow into equal streams that pass through several identical components. The physics necessary for this are simple: If the flow resistance of each piping path from a common source point to a common return point is the same, the flow will divide equally. Reverse return piping was developed to help achieve this goal.

Figure 1 shows a simple representation of reverse return piping through two identical components, each in its own branch piping. It also shows a direct return piping layout for comparison. The reverse return arrangement has the potential to create approximately equal flow resistance through each branch and produce flows that are closer to equal. The branch flows in the direct return system will not be equal. A higher percentage of the total flow will pass through branch No. 1.