A wood fired sauna heater is a sauna heater which uses wood as a source of energy to heat a sauna, rather than electricity or propane gas. Saunas were traditionally heated with stoves which had to be stocked with wood, and some traditional saunas still use wood heaters. Most modern saunas, however, use more clean burning and efficient forms of energy. The exception is a sweat, a type of temporary sauna which is built ceremonially by some Native American tribes. In this case, a wood stove may not be used at all, with sauna bathers instead creating a fire and surrounding the fire with sauna rocks.

Learning how to use a wood fired sauna heater is a complex process. For people who have never worked with wood stoves before, the first step is learning how to build a fire and keep it going. Each wood stove is slightly different, and the precise needs of the individual wood fired sauna heater must be learned. Part of learning how to use the stove involves which kinds of wood should be used, as damp wood will create smoke, and woods heavy in tar and pitch can make the sauna smell unpleasant. Fragrant woods like cedar and cypress are preferred, along with hardwoods such as oak, which will burn for a long time.

After learning how to build a fire and keep it going, someone can use a wood fired sauna heater relatively easily. They will need to learn how to operate stove flues to manipulate the flow of air to the wood fired sauna heater, which can make the fire burn hotter or cooler, depending on what is desired. A wood fired sauna heater also requires patience, because it will take a long time for the sauna to come to temperature. Furthermore, the temperature of the sauna cannot be as readily controlled, with changes to the oxygen level and fuel having an impact up to half an hour or more later.

Some advantages are conferred by a wood fired sauna heater. A wood stove can heat a very large sauna relatively quickly, especially if there is residual heat from the last usage. The wood fired sauna heater can also be kept burning continually at a low level with the assistance of slow burning hardwoods. Furthermore, differently scented woods can be used to create different atmospheres in the sauna, and it is easy to create sauna steam, or loyly, with a wood stove. Sauna bathers can simply splash the specially treated stove with water to create a cloud of steam. The larger surface area of a wood stove also allows for a sizable collection of sauna rocks. However, a wood fired sauna heater also requires much more space than a smaller electric or gas heater, and fueling it can be expensive in areas where access to wood is limited.