We have some passive solar heating panels. They are about 20' long and each section consists of 1.5" piping at each end with lots of 1/8" ID tubing running between them. Each section is about 2' wide. I have 4 sections connected together to create a panel that is 20' long by about 65" wide. Here's the best picture I could find. It shows 2 sections, I have 4.
I built a roof over the pool deck and last week had help getting the panels up on the roof and installed. I had them plumbed at ground level last summer. The line from the pool pump came in the top corner one end. The return went back to the pool at the bottom corner at the same end. Today I learned from my help that something fell out of one of the sections while we were putting them back together. He is not really a plumber and forgot to say something. It was at the end where I had the intake and return plumbed. Believe it or not I did find the part laying out there today, and it is a baffle. I -think- the baffle was there so that water would flow through the top half from one end to the other, then into the bottom half then flow back through the bottom half go back to the pool. Without the baffle I think water will just go straight through to the return. I think. So does it go between the halves at the end I have the intake and return? As an example, in the above pic water would flow in at the top, go to the far end of the top panel, then return through the bottom panel.