The exterior Chofu wood-fired heater has many advantages over submerged inside-the-tub heaters such as Snorkel. No occupancy loss: Inside heaters can take up as much as 1/3 of the interior space of your tub! But the Chofu does not take up any room inside the tub. This means you have 1/3 more space in the same tub — or you can get a smaller tub and have the same amount of space. Less heat loss: Inside heaters prevent the use of a full coverage insulated top so heat is lost. The Chofu heated hot tub can use a full coverage thermal blanket and cover drastically reducing heat loss. Less water level restriction: Water level should be kept over the tube of a snorkel heater to prevent warping the metal box — an approach that is prone to problems and wastes water. With the Chofu, the water level can be set much lower to eliminate wasted overflow.  No mess in the hot tub: Unlike interior wood-fired heaters the Chofu introduces no wood debris or ash into the water — helping to keep things nice and clean.