This excerpt is from The Ideal Fitter (1922). You'll find indirect radiators (both steam and hot water) within basement ductwork. Often, there is a connection to outside air, and warm-air discharge to floor- or wall grates in the rooms.
Here is the original Installation and Operating Instructions and Parts List for The H.B. Smith Company's Oil Fired Cast Iron Hot Water Boilers (No. OHB-13W). This is esti...
The Henry Ford Museum in Dearborn, MI has an interesting hot-water heating system. Take a look at the radiators below. They are from the Shaw-Perkins Manufacturing Compan...
We estimate that this cast-iron boiler catalog from The Peerless Heater Company in Boyertown, PA is from the 1980s or 1990s.