Here is a United States Patent for McDonnell & Miller's #11 Switch, dated October 28, 1941. Thanks to Gerry Gill for finding and sharing this one.
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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.
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Thanks to Gerry Gill for finding and sharing this patent. And thanks to Tim McElwain for these comments about the patent, "It looks like the prototype for what became Hon...
Thanks to Terry Tekushan for finding and sharing this one with us. He writes, "I thought this would be a nice addition to the museum. It goes well with Gerry Gill's submi...
Thanks to Gerry Gill for finding and sharing this patent. He adds, "We got nothin' on the old-timers!"
In London, during 1906, W. J. Connor published this Q&A booklet for those tasked with stoking coal-fired steam boilers.
Here's an interesting cleaning product for coal-fired boilers, circa-1950. Thanks to Michael Keefe Brewer for sharing.
Here is a wonderful explanation of what was involved with caring for a coal-heated home in 1943. (From The New York Times, 1944.)
Here is a report on the grades and size of coal from Spencer Heater's 1917 Steamfitters Handbook.

In the days before central heating life was hard. So hard, in fact, that it’s almost impossible for us to comprehend the difference that central heating made to people’s ...
Here is an interesting brochure from the Anthracite Institute. It is not dated, but was most likely published in the 1930s.