If the fresh air is blown into the sauna through the ceiling, there is no need for an exhaust vent. As the air moves downward, it is finally discharged under the door to the washing room with the effect of drying and warming up the air there. If an exhaust vent is installed, the best place for it is near the floor below the laude. When the hot air rising up from the stove can not dissipate at the ceiling level, it must come down to the level of exhaust i.e. to the floor. This creates a warm airflow from the ceiling to the floor minimising the temperature differential and forcing the warm exhausting air in to the washing room.
Instructions often locate the exhaust on the back wall behind the laude, between the uppermost and the second laude. This is not advisable, as the temperature would fall sharply at the level of the exhaust vent, since the hot air coming down does not go below the vent. It makes the legs "freeze," if the vent is much above than the second laude. The sauna maintenance gets also difficult, because the lower part of the laude stays wet, possibly causing foul smell and mould. The over-pressured ventilation is recommended especially in the saunas of swimming pools, hotels and other public places where there is a constant turnover of people and the sauna door is open most of the time.
© Saunasite, 1997