In this video, Dan Holohan tells us about indirect heating. It is a method of heating that the old-timers used to warm fresh air before it entered a building. They placed the indirect radiators outside the room they were heating (that’s where the name “indirect” comes from). They used ductwork to direct the fresh outside air across these remote radiators where it would be warmed before rising into the rooms.
The radiators were almost always in the basement, and usually right under the room they were heating, but they could also put them in a central location and feed the ductwork off to the rooms. It all depended on the size and shape of the house.
This system was often used in very big houses. Indirect heating was mostly the province of rich folks. Rich folks loved this type of heating system.
At the Turn of the Century, many people believed stale air (they called it "vitiated air") was a prime cause of disease. Those who could afford it heated their homes with a constant supply of warmed, fresh air. They thought this was the healthiest heating system possible.
Want to learn more? Read Dan Holohan’s book The Lost Art of Steam Heating Revisited.