One of the earlier gravity-hot-water-heating devices. Water would stratify in the horizontal main, with the hottest water rising to the top of the pipe. It left the tee and flowed to the radiator though the tee's top tapping. Cooler water from that radiator entered the same tee though the side tapping. Interesting things happen when you add a circulator to a system that has these tees. Thanks to Gerry Gill for finding and sharing the patent.
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This chapter on hot water heating systems and piping was prepared by Professor F.E. Giesecke (Director of Texas Engineering Experiment Station in TX) for the The American...
Here are ratings for the Erie radiator from Jarecki Mfg Co Ltd. They were based in Erie, PA and their radiators appeared in issues of Domestic Engineering in the 1890s.
Brian Roberts & Paul Yunnie compiled this document that contains beautiful vintage advertisements and illustrations of radiators from the mid to late 1800s and early 1900...