Take a stroll through HVAC history in our Heating Museum. This section of our website preserves history and answers that so-important question: What the heck is that thing? Whenever you run across anything unusual, chances are you’ll find the old literature about it right here.
The Hoffman - A Venting Valve for Every Service shares the Hoffman story, as told 30 years after George D. Hoffman introduced his first vent. Wonderfully clear language h...
This is an interesting article about the steam loop from The Manufacturer and Builder magazine, January, 1892. It still works today.
Here is a nice explanation of thermostatic traps by Austin Roche, Chief Engineer for Hoffman Specialty. This appeared on June 13, 1952.
Trane made some of the finest vapor heating equipment in the world. This catalog explains how their heating system works, and it shows the insides of all the equipment.
This document is called "Trane: The Complete Line, featuring the Trane Lifetime Valve" and contains information about Trane traps, vents and supply valves. Thanks to Patr...
This booklet features one of Trane's earliest systems for producing vacuum in a steam system, through the use of a pot filled with mercury and specialized air valves.
This William Moore article from a 1935 edition of Fuel Oil Journal does a nice job of explaining how vacuum vents once worked on one-pipe steam systems.
Here are installation and operating instructions from Dunham-Bush about the Vari-Vac Differential Controller Model 389 K. Thanks to Brad White for finding and sharing thi...
Here is information from MEPCO (Marshall Engineered Products Co.) about the Vari-Vac Differential Heating System. Thanks to Brad White for finding and sharing this inform...
This installation, operation, and maintenance manual from Dunham-Bush contains information about the Vari-Vac DTS-2 Programmable Timer. Thanks to Brad White for finding a...