Believe it or not, cast iron was invented in China around the 5th century BC, it was poured into molds that were then used to make things such as weapons, pots and ploughshares.
A long time later in 1855 Franz San Galli, a Russian businessman invented the first cast iron radiator.
Before the invention of the radiator, man relied on coal, a highly toxic fuel. The only way to heat ones house if you was lucky enough was by a fireplace or stove
In the late 1800s the American Radiator Company choose to promote this over steel designs due to the lower cost of manufacturing cast iron, they then expanded the market.