My assumptions are based on my 27 year experience within the heating supply and installation business and with disscussion with designers and importers of stoves over this time. Up until about 20 years ago these stoves and range stoves was the only heat source in the majority of Rural Irish homes. They provided hot water and heat only to one main room and was also used for cooking. The basic design has not changed since then but on some models baffels are introduced in the flue system to improve efficiency.Thanks to improvements in plumbing and water circulation pumps,stats/motorized valves and rads, stoves are now be used as a central boiler for heating and or assisted heating on dual systems.