Few would argue that fin-tube baseboard was the “flagship” heat emitter in North American hydronic heating systems through much of the 20th century. Its origins go back to the 1930s, where it represented radical departure from the status quo of cast-iron radiators. Since then, it has maintained its place in residential hydronic systems, despite the fact that its fundamental construction hasn’t changed much.
A typical residential fin-tube baseboard system connected multiple baseboards into either series or “split series” circuits, as shown in Figure 1.