The choice of stones depends on the stove and the use. In a wood burning stove, the stones must store the heat after the fire has burned out. Therefore, the best choice is a stone with a lot of energy storing capacity.
With electric heaters and stoves, the energy storing capacity is not quite as important, because the heating elements can be on all the time. If a heater is undersized, a large energy storing capacity is useful, as additional energy is needed for loyly throwing. If the heater is correctly sized for the sauna volume, one can use stones that warm up faster and save energy. The newly developed ceramic stones are almost one third faster and also lighter than the traditional stones.
In theory, the most suitable stone for one set of bathers would be hollow. A hollow stone gives up all of its energy, retaining none when the sauna-bathing is over. The stones with a large energy storing capacity and all large stones retain a lot of energy after a sauna-bath. If there is no need to save heat and loyly to the next bather, there is no use for large energy storing capacity.
In the heavy use saunas, like in public swimming pools, the durability of the stones is important. The stones crushed from a rock last 2-3 months while ceramic stones last about one year. Furthermore, ceramic stones are cleaner, because they do not crumble like ordinary stones. The higher cost of the ceramic stones is compensated with the durability and the energy saving which is equivalent to 10-15 minutes time of warming up for each sauna-bathing.
The maintenance of the stones is an important part of the sauna maintenance, because the crumbled stone may stop the airflow through the stove. If the heating elements do not cool off adequately, their durability diminishes progressively. It is said that if you do not change the stones, you must soon change the heating elements, which is much more expensive and labor intensive.
The stones should be checked periodically. The top stones often look better than the stones below. The stones just above the heating elements get the heaviest burden, because they get the hottest heat from below but also the loyly water from above. The extreme temperature changes cause frequent thermal expansion and constriction. Although small, the expansion creates a little crevice, eventually cracking the stone. The small cracked stones fall in between the larger stones below and block the airflow through the stove, which may burn out the heating elements.
The positioning of the stones is not very important, as they keep moving slightly because of the thermal expansion and constriction of metal and stones. Although the size of stones is not very important, it is important, however, that the stones are of the same size. This will prevent the smaller stones from blocking the gaps between bigger stones, and thus stopping the airflow through the stove.
It is commonly suggested to place bigger stones below and smaller stones above. This may be good advice for heaters with small amount of stones. It not advisable for stoves with many layers of stones as the smaller stones will fall into the gaps between the bigger stones, and block the air flow. The sauna does not warm up as fast as before and the heating elements may burn out faster.
When changing the stones, they should be washed carefully. In a brand new sauna with energy storing stove and plenty of stones, a lot of dirt will loosen from the stones however carefully the stones are washed. This is because the loyly acts as a vaporized rinse loosening even more dirt from the stones. The dirt spreads out to the ceiling with loyly and may spoil the new paneling. This can be avoided by placing a cheesecloth on the stones for the first loyly to collect the dirt particles.
© Saunasite, 1997