Cozy 12 Quattro Wood Burning Sauna Heater – 12kW Firewood Sauna StoveMild, Long Lasting Heat with the Quattro Design The Cozy 12 Quattro is a wood burning sauna heater engineered for soft, enduring warmth and rich steam. Built in Estonia by specialists with generations of sauna know how, its optimized for throwing water onto hot stones and delivering a traditional lyly. With a tested thermal output of 11. 5 kW, the Cozy12 Quattro suits sauna rooms of 613 m and is available in INTERNAL or EXTERNAL (through wall)