What to consider when choosing the correct power for a sauna heater
The volume and structures of the sauna affect the selection of heater power. An average of 1 kW of heater power is required for each cubic meter of sauna volume (1 m³ = 1 kW).
The power requirement increases if there are window surfaces or heat-storing surfaces such as brick, concrete or massive logs in the sauna. One square meter of stone, glass or similar non-insulated surface increases the heater power requirement as much as if the sauna room volume were increased by 1.2 cubic meters.
If the interior walls of the sauna room are made of non-insulated logs, the corresponding factor is 1.5.
Note
- The recommended heater power (kW) provided by the sauna calculator is, in most cases, the minimum required power.
- If the heating capacity is too small, the heater needs to be heated longer and more intensely, which reduces its life span.
Calculate the volume here - Harvia Sauna Calculator
Choosing a heater based on the results of the sauna calculator
- The minimum and maximum volume of the sauna room (Min-Max m³ scale) is specified separately for each heater.
- Optimal power is achieved when the heater is selected based on the sauna volume (m³) calculated by the sauna calculator, choosing a heater within the midpoint of its specified minimum-maximum range (m³). See the example below:
Example of Choosing an Electric Heater
Based on the dimensions and glass surface (door), the calculatory volume of the sauna room is approximately 8.5 cubic meters, which means the heater must have a minimum output of 6 kW.
The optimal heater choice for the sauna mentioned in the example would be Cilindro PC70XE (6,8kW)
- The optimal sauna room volume for the PC70XE model is approximately 7–9 m³, which is halfway along the scale indicated on the heater.
Mechanical or electronic heater model?
When choosing a sauna heater, it’s worth considering the differences between mechanical models and those equipped with a separate control panel and temperature sensor:
- Mechanical heater (equipped with a mechanical timer and a thermostat) measures the heater temperature using an integrated capillary thermostat, with the sensor permanently located inside the heater. The traditional manual model is more affordable, and its installation and use are simple, but due to the internal thermostat, it cannot measure or regulate the sauna room temperature as accurately as models equipped with a separate temperature sensor.
- Electronically controlled heater (equipped with a separate control panel and temperature sensor) measures the sauna room temperature with extreme precision - allowing you to adjust the temperature via the control panel with an accuracy of up to one degree (C). As a result, the temperature remains more stable and closer to the desired temperature if compared to mechanical models. See the instructions and tips for installing the temperature sensor.
Tips for choosing a sauna heater
- When choosing a sauna heater, try to avoid the minimum and maximum values (m³) of the specified volume range: For example, if the calculated volume of your sauna is 9.5 m³, the Cilindro PC70 (6–10 m³) is not the best choice. In that case, always choose the slightly more powerful PC90 model (8–14 m³).
- If you are replacing an old wall-mounted heater with a new pillar-style heater that holds more stones, the new heater should have a slightly higher output (kW):
- Replace your 6 kW heater with a new 7 kW pillar heater (+1 kW)
- Replace your 8 kW heater with a new 9 kW pillar heater (+1 kW)
- Make sure the fuse sizes and power cables are adequate as the heater's power increases!
Try using our sauna calculator:
Calculate the volume here - Harvia Sauna Calculator