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This article about steam heating is from an 1871 edition of Van Nostrand's Engineering Magazine. Note the highly critical comments regarding those who tended the boilers.

Thanks to historian, Bernard Nagengast, for sharing this circa-1905 article from American Electrician magazine, which does a great job of explaining the steam traps, and ...

In 1935, John W. Schulz, writing in Fuel Oil Journal, makes a brilliant case for looking more closely at steam systems designed with coal in mind when the time comes to s...

This circa-1916 bulletin from C.A. Dunham Co. describes Dunham's heating product offering for a system to compete with Andrew Paul's heating system.

This bulletin from C.A. Dunham Co. is from 1916 and features the Dunham Blast Trap and Its Application.

Packless radiator supply valves kept air from working its way into a vacuum system. This bulletin from C.A. Dunham Co.

This bulletin from C.A. Dunham Co. is from 1916 and features the Dunham Reducing Pressure Valve and Vacuum Pump Governor.

This circa-1916 bulletin contains helpful information about the Dunham Vapor Heating System. Thanks to David Cordes for sharing.

The Dunham Victory line appeared in 1943 and had to meet Government specifications since we were at war. Note how the Vari-Vac system was then called the Dunham Coordinat...

This is a very clear explanation of the Hartford Loop. It's from the Western Plumbing and Heating Journal and it appeared in April, 1943.