@ehBeth,
I'm no smartie on house plumbing but I used to be a whiz at irrigation design, most of which I don't remember at all by now, except drawing fast fast fast as deadlines lurked. One's hand could cramp - this was just before CAD. I do still recognize the word "pipes".
I might be able to google this, but others would probably be better at that, and could get a flash for their efforts. Sounds like an installation problem.