Trying to visualize the dynamics of this split method. I have nothing to back it up, but what I'm seeing is water taking the path of least resistance and mostly going through only one side of the chiller. Seems like if the pipe size had been reduced down when branched the volume in each section would be constant, but the way it is wouldn't one side be relatively stagnant while the bulk of the water went the other way? It looks like the two sections aren't equal lengths, so that would contribute to lack of efficiency in the longer section. I really don't know. Any plumbers or engineers care to chime in?