The heart of any sauna is its heater. Sauna heaters must be specially designed to be able to produce a consistently high temperature. There are several types of heaters available, but the most common are electric heaters. Wood-burning heaters are popular in rural areas, and oil and gas heaters are also sometimes used.

The sauna heater is responsible for creating heat and steam. Stones are piled on the heater to retain the heat and produce steam when water is poured over them.

Electric Heaters

Electric models were introduced in the 1930s. Prior to that, all saunas were heated with wood. Aficionados feel that wood produces the best type of heat for a sauna. They describe it as a 'soft' heat.

Unfortunately, wood-burning heaters are not practical for most urban areas. For this reason, electric heaters are now the most popular.

Electric heaters are usually enclosed in a protective casing to prevent burns if bathers accidentally touch them. They are controlled with a thermostat mounted outside the sauna. The desired temperature is set and the heater stays on while it is being used. Electric heaters take about 30 minutes to bring the sauna to the desired temperature.

Wood-Burning Heaters

For those who have a house in the country, a wood-burning heater is a good choice for a sauna. An ample supply of firewood in many rural areas ensure economical operation. Some wood-burning heaters have glass doors, and watching the flames while taking a sauna can add to its calming effects.

Wood-burning sauna heaters are combustion chambers with a controlled air flow. The amount of air flow determines how fast the wood burns. A lesser air flow makes the wood will burn slowly, and greater air flow makes it burn faster. Controlling the air flow also controls the temperature to a large extent, but there is no way to set a wood heater at a certain temperature like an electric heater. Smoke is not released into the bathing chamber; instead it is drawn upwards through the metal chimney pipe installed through the roof.

Oil and Gas Sauna Heaters

Oil and gas heaters are sometimes used for saunas but are less common than electricity or wood-burning heaters. They are relatively inefficient, especially when compared to electric heaters, and some people complain of the odor associated with the burning fuel. However, properly vented oil and gas heaters should have no discernible smell.

Stones

Every sauna heater needs stones. Any type of rock can be used, but some are better suited. They help retain the heat and produce steam when water is poured over them. They have to endure a lot of stress. The constant heating and cooling requires them to have special qualities to withstand the fluctuating temperatures without cracking. They should also be odorless when heated. They should have a rough surface (to release steam faster), be free of cracks, and able to retain heat. Popular varieties are peridotite and olivine, both available at sauna supply stores.