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
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 ones 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.
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
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.
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:
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: