Deficiency: Recommend replacing 2 1/2" OS&Y valve that is leaking. It is the shutoff before antifreeze loop. Tried to tighten packing. Bolts will not turn due to rust and corrosion. New 2 1/2" OS&Y valve Flange to Flange is 7 5/8 4 bolt 4" center to center on bolt holes with 3" bolts 8 3" new 5/8 bolts 2 gaskets