It is super common in Japan for domestic hot water heating. It was pioneered by the government of Japan, electronic goods firms, and the power companies. You'l

It is super common in Japan for domestic hot water heating. It was pioneered by the government of Japan, electronic goods firms, and the power companies. You'll see them sold under the EcoCute name. Daikin, Panasonic, and Corona (no relation) make them. They get used for homes meant to only have water and electricity hookup, called "all electric" homes.