Heat retention and even heat distribution with oscillating feature. Built-in thermostat and dual function for heating and cooling. Quiet operation even at full power. Safe design without getting hot to touch. Timer and remote control included
Bed warmers using hot coals were used since 16th century. Early bottles were made from zinc, copper, brass, glass, earthenware or wood. India rubber bottles were used in Britain by 1875
Kotatsu originated in Muromachi period (14th century) as hori-gotatsu. Early kotatsu used charcoal brazier under wooden platform. Modern oki-gotatsu evolved with tatami matting and electric heating. By 1997, 81% of Japanese homes had electric kotatsu