Is it true that solar collector panels with “flow-balancing” plenum chambers perform better than other solar collector designs?
No. The idea is that flow–balancing plenums–secondary water chambers between a solar collector’s headers and the flow passageways of its heating surface–provide more balanced water flow throughout a bank of solar collector panels, and thus more efficient heat transfer. But this is a solution to a non–existent problem. A basic rule of fluid hydraulics is that flow rates will vary in parallel pipes so that the head losses are equalized through each flow path. In plain English, if the diameters and lengths of the individual parallel flow passages in a solar collector are identical, the flow rates through these passages will be identical. This is always the case in a correctly installed solar pool heating system. The only practical effect of additional flow restriction in a properly installed solar pool heating system is increased workload for the pump. Here’s how this idea got started. During the 1970s, a solar collector manufacturer developed a process for heat–welding the heating surfac
