I am installing an active open loop solar water heating system. The tank has a side connect to attach the return line from the collectors. But, the installer insists that connecting the return line to the drain at the bottom of the tank is better. My instinct says that he is wrong, because you are sending hot water that just came from the collector back to the collector (the connection to the collectors is only a few inches away) which isn't very efficient. Also, the only way for the hot water to reach the top of the tank is through a slow convective process, unless you use a lot of hot water, pulling the water up from the bottom. His claim is that with a side connect, the hot water doesn't reach the bottom and so you are only using half the tank. But, I think that is wrong, because the pump is forcing the hot water down. Does anyone know of any studies or evidence that a bottom connection is better? It seems that if it were, the manufacturer of the tank would have moved the "From Collector" connection.