Measure the room in cubic feet, add a little for any glass or tile, then pick the heater whose rated range puts your room near the middle. The table below matches common room sizes to heater sizes. At a glance Rule of thumb: about 1 kW for every 35 cu ft of room (Harvia’s rule,…
Match the stove to the room first. Every maker rates its stoves in cubic feet of hot-room volume, and that number decides more than brand does. Then choose whether you load wood from inside the hot room or through the wall, and in the US, check the safety listing with your building department before you…
Sauna stones are not decoration and they are not interchangeable with rocks from your yard. Buy olivine diabase sold for heaters, stack them loosely by hand with the big ones low, and check them once a year. Old, tightly packed stones heat the room slower and force the element to run hotter than it should….
The heater is the heart of your sauna. Get it right and you’ll have decades of proper löyly (the burst of steam when you throw water on the stones). Get it wrong and you’ll have an expensive closet that gets sort of warm. The difference between a $500 heater and a $2,500 one isn’t just…