So, here is the weir-derived overflow and return for the RSM. The intake pipe draws water from the passage under the skimmer, up and out the chiller port, down and up again to the air vent, then across and down to the sump. Return comes up and across the top of the vent, through the chiller port and under intake, and deposits water into the circulation pump intake. It all fits flush against the back of the tank.