The idea of heating up a building with a heating device is not new. In earlier centuries, the Romans would burn coal underneath brick buildings. This worked as powerful insulation for heat in the winter months.
Later, there was a safer option invented called the chimney. The chimney did just as good of a job; however, it was safer due to the smaller area of flames. Finally, into the modern era, a better method was discovered. Instead of using wood or coal as the fuel for the heat, gas was used.