The heater is often called the “heart” of the sauna and plays an important role in heating the sauna. If the heating power is insufficient, the furnace must be operated for a longer period of time and at a higher power, which reduces the service life of the furnace. The heating capacity of the furnace may not be sufficient to reach the desired temperature. To determine the correct heat output, several factors must be considered. In this article you will find useful information and some rules to make the right decision.