In a gravity hot water system, the hottest water is near the top of the horizontal main and tends to travel first to the upper-floor radiators. Mr. Honeywell, in 1909, patented this invention to help balance these systems. With Honeywell's tees in place, hot water would have to fill the entire pipe before any water would enter the radiators. The hot water had to slide under that internal cuff inside the tee to get to the radiators, so all the radiators heated at the same time. Beautifully simple!
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...