The best heater is not just the one with the biggest number on the box. Room volume, glass area, stone mass, bench height, ventilation and the way you want to use the sauna all matter.
Traditional, hands-on heat with a real fire. Best where chimney placement, clearances and wood handling can be designed into the build from the beginning.
Clean and controllable. A strong option for indoor saunas and sites where convenience and predictable heat-up are priorities.
Wood-fired systems have to be laid out around the actual stove, chimney components, roof or wall penetration and manufacturer clearances.
They store heat and turn water into löyly. Stone quantity, heater design and room volume change how quickly the sauna responds and how the heat feels when water hits the stones.
Read about Löyly