All that changed in the ’80s when the boilers got smaller. They had to get smaller so they could meet the call for higher combustion efficiency. The internal sections got narrower and the steam now had to climb through a tighter space. That led to more violent waterlines and wetter steam. The steam-disengaging space also got smaller and made things worse. Oh, and the exit holes in the boilers shrank, which led to exit velocities that had the steam pulling the water out of the boiler and into the system. That gave us uneven heat, high fuel bills, and —quite often — water hammer.
Weil-McLain, to its credit, drags a big steam boiler to the trade shows in the East. They cut a porthole in this boiler so folks can see what goes on inside. And they pipe the boiler perfectly with glass pipe because seeing is believing, and this boiler is there to make people believe.