After an extensive amount of research, I'm still not quite getting the open storage concept. Why is a heat exchanger necessary between the gasifier and open storage? Why can't I put a line at the bottom of my tank, add a circulator, and run it through the gasifier and back into the top of the tank (assuming the gasifier is pressurized)? Also, if I use a flat plate HX, aren't I running a line from the bottom of the tank, through the HX, and back into the top of the tank? What does the HX add (besides maybe freeze protection if I use glycol)? In terms of extracting heat from the tank, can I siphon water off the top of the tank, run it though a injection pump to create optimal temperature, and then through the supply zones? Or would I need to have a HX between the tank and supply lines as well? If so, why? Any and all responses are greatly appreciated.