If you teach in Japan you will end up seeing one of these "things". It's basically a hot water heater. Some are automatic and some are manual. At the JHS I work at it turns on when you turn on the hot water. You hear the gas ignite and all!! I don't think they are very safe, but I guess they have been perfecting the technology for decades....
I wonder what's more "Eco" heating as you go (Japanese Style) or having a big water heater and tank. (Western Style)?
