There are many sauna stoves. They can be classified according to various criteria. For example, according to what energy source is used, they are gas, solid fuel and electric. According to what material they are made of: metal and brick. According to the temperature that the outer walls adhere to, they are cold and hot. As for stoves, where heating occurs constantly, their characteristic feature is the inability to take a steam bath when heating is carried out..
If you are using a hot stove, then you should not overheat the steam room, because then you will not be able to restore the necessary humidity in the room where the stove is located. And if there is no proper humidity, then it will not be a bath at all, but a sauna. By the way, sometimes a link is useful on the Internet, you can find useful information there..
That is why the cold heating oven is much better than the previous version. In addition, if you use this type of oven, you can easily control not only the humidity, but also the temperature you need. In general, do not get hung up on any one option. Study the technical characteristics of any individual oven and only then make your choice. Haste in this matter is useless, first of all, take care of your own safety.