Heating Museum Help Topics

This circa-1936 patent is for the Hoffman Specialty Company's boiler return trap for heating systems. Thanks to Gerry Gill for finding this patent, and for sharing it wit...

Here is the Hoffman Data Book for Heating Engineers and Contractors, Second Edition compiled for the Hoffman Specialty Company in 1925. "The Hoffman devices which transfo...

Here are patents from 1922 for the Hoffman Specialty Company for their vapor heating system with differential loops. Thanks to Steve Pajek for finding and sharing these.

This catalog for the Hoffman Specialty Company from 1929 showcases their heating equipment, including Hoffman valves, Hoffman controlled heat, Hoffman-Economy pumps, and ...

This document is from the sales department at the Hoffman Specialty Co. in 1926. It showcases Hoffman Valves and Controlled Heat Equipment with cutaway diagrams of how th...

This book, Hoffman Venting Valves for Every Purpose, was from the Hoffman Specialty Co. in 1918. It includes a lot of information about Hoffman valves for heating systems...

Here are comprehensive instructions from 1916 from the C.A. Dunham Company about How to Install The Dunham Vapor Heating System. Thanks to David Cordes for sharing.

Here is a wonderful little book from Hoffman Specialty from 1927 called How To Lock Out Air: The Heat Thief. It includes some great pictures. It makes the case for steam ...

Wait until you see this wonderful invention from 1922! We wish they still made these. This is the patent for M.G.

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...