A traditional sauna generally takes between 30 and 45 minutes to fully heat up. During this time, the rocks will be heated to the perfect temperature for soft heat and soft steam. With the addition of a Saunatonttu heater, the sauna heat up time is halved. It takes about 10 minutes for an infrared sauna to heat up. After 10 minutes, the air has warmed up a little and the emitters are running at full power.