RobinhoodtheFetchling suggested this as a new furance.
https://en.wikipedia.org/wiki/Regenerative_heat_exchanger
https://en.wikipedia.org/wiki/Hot_blast
Basicly it could be added as a "bigger" furnances to the game since this one can be "upgraded" to support more Cowpers which mean more production. At the moment we build 4-5 furnances in a row for each material but this one could be more fuel effient and for bigger production lines.
