The Hutchison Vapor Heating System is very simple once you know how it works. There is no trap at the individual radiators. The returns are trapped at the boiler by means of the Hutchison trap-receiver and damper regulator combination. Here is a diagram from a 1923 edition of The Heating and Ventilating Magazine.
This document contains the complete illustrated instructions for installing the Hercules Steam and Hot Water Heating System, a boiler manufactured by Sears, Roebuck and C...
This document contains the manufacturer's instructions for the HB Smith Series M450L Mills Water-Tube Boiler for automatic firing with oil or gas (Steam, Vapor, or Water ...
This document contains the jacket assembly instructions for the HB Smith Series 45 Mills Boiler (circa 1979).