http://www.csmonitor.com/2005/0421/p14s01-sten.html

this article (scroll down for the bit about water heaters) makes it sound like japan has only recently used this kind of heater, but it was in use at least 10 years ago.

i am glad it is becoming available in the u.s. it just totally makes all kinds of sense, financially and ecology-wise.

if/when we get a house, i totally hope to install one.