Cozy Heat Quattro Thru-Wall Sauna StoveWood Burning Sauna Stove, Up to 18kW The convenient Cozy Quattro 12 TW through the wall wood burning sauna stove is hand made in Estonia, where sauna bathing is a daily ritual. Wood burning stoves create a mild and long lasting heat and are designed for ladling water over the hot stones to create a satisfying steam sauna. Its through the wall design allows you to load firewood from outside your sauna. Sauna room sizes: 12kW for saunas from 210 to 423