The workshop classroom in the basement of St. Jude’s Technical Institute smelled of cutting oil, flux smoke, and damp concrete. Eighteen young apprentices—boys and girls in stiff blue denim work jackets—sat on backless wooden stools around a forty-foot working hydronic test model loop. A fine, detailed maze of two-inch copper and black iron pipes, circulator pumps, motorized balancing valves, and spreading tanks.
Ada Morland stood at the head of the loop. Her left forearm was bound in a light, clean elastic bandage that left her wrist and fingers fully free. She wore her standard navy work overalls, her brass measuring tongs sticking out of her breast pocket like a pen. Beside her, Ben stood holding a clipboard with the system’s pressure schematics, his chest puffed out slightly in his role as test assistant.
“Put your pipe wrenches on the floor,” Ada said. Her voice carried through the basement with the calm power of twenty years in the trade. “Every one of you. Put them under your stools.”
The apprentices paused, then laid their heavy steel tools on the concrete with an irregular clatter of iron.
Ada walked to the end of the test model loop. There, a cutaway section of a heavy-duty three-way mixing valve was mounted on a steel display stone stand. ‘Look at this casting, class. Cast iron body, bronze plug, stainless-steel stem. Under ordinary city water pressure, this valve handles fifty gallons a minute without a whisper. But if the pressure differential between the supply and return…
