As a result of construction coming up (I get a shear wall in the middle of my basement to support a second story on the house), I am tearing down my entire layout. While the new layout is the same in spirit, it will be a very improved version with detection and signaling across the whole system (right now I only have it on half the system) and of course ... better radii. 24" main/ 18" branch is now going to 30" everywhere, and much tighter tolerances are to be demanded in construction.
This is Rev 1 of Layout 2.0, ready for your feedback! The room is 22' x 16', each square is 1'