- The sauna is too small in relation to the stove’s heating capacity. See the stove selection instructions.
- The flue does not have a good draught.
- The burning material is moist or its quality is otherwise low.
- The smoke ducts of the stove are blocked. Clear the smoke ducts.
- Check how the stones are stacked. Remove small pieces of stone and stones that are less than 10 cm in diameter from the stone compartment. Replace disintegrated stones with large and undamaged ones.