THE STOVE

The most important element in a sauna is the stove. The löyly, the overall feeling when taking a sauna-bath, is considered to be best in a sauna where there is a stove, not a heater. The barrel-stove and the ancient smoke-stove are among the best. The best stoves have the following common features:

· The heat is stored in a large amount of stones
· The temperature in the sauna is quite mild, 60-80 ºC
· The feel of warmth is regulated by throwing water onto the hot stones

Click to see this image bigger... There is a picture of an ancient smoke sauna: The stove stands on the floor, and the laude can be reached by a stepladder. Since there is no chimney, and the sauna fills with smoke when heating the stove, the sauna must be aired out thoroughly before sauna-bathing. This ventilation brings the temperature down in the sauna.

The same happens with the barrel-stove, which heats up the sauna to 40-50 degrees before opening the lid. The low temperature makes it possible to throw löyly i.e. steam water on the hot stones. By throwing löyly, it is possible to regulate the feel of warmth. As the sauna becomes hotter during the löyly-taking, one can get the most comfortable mix of heat and humidity, i. e. just the right löyly to one’s liking.

The stove is the heart of the sauna. Without a good stove, there can not be a good sauna in spite of all the possible luxuries and money spent on construction. The löyly is a combination of the temperature in the sauna and the steam generated from the water thrown on the hot stones of the stove. Traditionally, the temperature in a sauna is low enough for tossing water on the stones, and in this way regulating the löyly. This means that the temperature in a sauna is essential for good löyly.

As told in the Temperature and Löyly chapter, it is not possible to take a wet löyly in a hot sauna, because maintaining the relative humidity at the high temperature requires increasing löyly-throwing, which in turn raises the heat effect to an intolerable level.

Click to see this image bigger... The requirement for a good sauna, and also for a good löyly, is that the temperature in the sauna is so low that one can take also a wet löyly. This can be accomplished only in a sauna, where there is a stove with plenty of stones. A heater with some stones has not adequate löyly-capacity to give a wet löyly.

The temperature for a good löyly varies a lot for different people. That is why it is also important, that the stove heats up the sauna hot enough for those who prefer hotter and dryer löyly. If the temperature in the sauna is too low, the löyly is too wet.
There is no one type of unambiguously good löyly, rather many kinds of good löyly, each appealing to different people. In general, men like hotter löyly than women, and adults take harder löyly than children.

Most every sauna can be heated so that it appeals to the owner but that presumes that one must take the löyly just as the sauna is "ready", i.e. as soon as the temperature has reached the desired level. Otherwise the sauna gets burning hot if bathing delayed.

A good stove allows for any kind of löyly. In general, stoves are better but also more expensive than heaters. A stove gives a great variety of löyly possibilities: from a heater-like hot dry löyly to a wet Turkish-type steam-bath.

Click to see this image bigger... The stoves are also safer than heaters. The casing of a stove never gets burning hot. In addition to the fire safety, an important safety aspect is also that the bathers do not burn their skin if they accidentally touch the stove. Children do not have a fully developed ability to dissipate heat by perspiration, which means that they do not tolerate heat as well as adults. With a stove, it is easy to give children a milder löyly without loosing the possibility of a harder löyly for yourself.

A stove consumes less energy than a heater. If the sauna is on, but empty waiting for bathers, the difference in energy consumption is vast. A stove with the closed lid uses only 0.3 to 2 kW hours , whereas a heater uses 3 to 30 kW hours. With heat stored into its stones, a stove can manage with less energy than a heater.

If the ceiling and the walls of a sauna are carefully insulated and paneled, a good rule of thumb is that the effect of the heater should be about two times the floor area of the sauna (measured in square meters).

As an example, if the area of a 210cm x 240 cm sauna is 5 square meters, the effect needed is 10 kW hours. (Or, the effect needed is one fifth of the floor area in square feet: 48/5=9.6 kWh).

A stove needs less capacity to produce the same effect. The energy stored in the stones and the electric capacity are adequate to heat up the sauna and to give enough löyly for a group of bathers.

Only in the case of continuous bathing and throwing of löyly, there is a need for more capacity, as the steaming of water consumes a lot of energy.

Another advantage of a stove vs. a heater, is that it saves the panelling. The panelling dries out too much if the sauna is extremely hot for extended periods of time. With continuous heavy use of an electric heater, the panelling in a sauna may have to be changed every two years.

With a stove, the sauna is hot only when there are bathers in it, which lessens the heat burden to a fraction. Furthermore, there is no need to heat up the sauna burning hot, as there is no fear for the lack of löyly.

As there is a great variety of heaters and stoves, there is also a great variety in their prices. In Finland, the approximate price levels in US dollars are:

Electric heater, wall model 3-9 kW $ 100-300
Electric heater, standing on the floor 12-36 kW $ 600-2,000
Wood-burning heater   $ 100-300
Electric stove, type always-on 3-8 kW $ 700-1,200
Electric stove, Magic Stove 4-30 kW $ 2,400-7,000
Wood-burning barrel-stove   $ 800-2,000



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