A wood-burning stove creates a traditional sauna experience with natural heat, hot stones and the atmosphere of a real fire.
When choosing a wood-fired outdoor sauna, one important decision is whether the stove should be fired from inside or outside the sauna.
Both options can heat a sauna effectively. The main difference is where the firewood is loaded and how the stove is operated.
What Is an Internally Fired Sauna Stove?
An internally fired sauna stove is loaded from inside the sauna room.
The stove, firebox door and sauna stones are all located inside the sauna. To add firewood or adjust the fire, you enter the sauna and open the stove door.
This is the traditional and most common option for private outdoor saunas.
Advantages of an Internal-Fire Stove
An internally fired stove is generally simpler to install and is often more affordable than an externally fired model.
It also allows sauna users to see and hear the fire from inside, which many people consider an important part of the traditional sauna experience.
This option is particularly suitable for:
- private residential saunas
- smaller outdoor saunas
- customers who enjoy managing the fire themselves
- projects where installation simplicity is important
Points to Consider
Firewood must be carried into the sauna, which can bring in bark, ash and small pieces of wood.
The stove door and required safety area also take up space inside the sauna. Refuelling may briefly disturb other sauna users.
What Is an Externally Fired Sauna Stove?
An externally fired sauna stove has an extended firebox that passes through the sauna wall.
The main stove body and sauna stones remain inside, but the firewood is loaded through a door outside the sauna or from an adjoining changing room.
These heaters are also known as external-firebox, outside-fed or through-wall sauna stoves.
Advantages of an External-Fire Stove
The main advantage is that the fire can be managed without entering the sauna.
Firewood, bark and ash remain outside, helping to keep the sauna interior cleaner. Users are also not disturbed when more wood is added.
An externally fired stove can be especially useful for:
- commercial outdoor saunas
- hotels and wellness facilities
- rental saunas
- saunas used by larger groups
- customers who prefer a cleaner sauna interior
- saunas with an adjoining changing room
Points to Consider
An externally fired stove requires more planning because the firebox must pass safely through the sauna wall.
The stove position, wall opening, heat protection and bench layout should therefore be considered before the sauna is manufactured or assembled.
Externally fired stove models can also cost more than comparable internally fired heaters.
Internal vs External Sauna Stove
The right option depends mainly on how the sauna will be used.
| Feature | Internal Fire | External Fire |
|---|---|---|
| Firewood loading | Inside the sauna | Outside or from changing room |
| Installation | Usually simpler | Requires through-wall installation |
| Cleaning | More bark and ash inside | Cleaner sauna interior |
| Refuelling | Requires entering the sauna | Users are not disturbed |
| Typical use | Private saunas | Private or commercial saunas |
| Cost | Usually lower | Usually higher |
Does an External Stove Heat the Sauna Differently?
Not significantly.
With both systems, the stove body and stones are located inside the sauna room. The fire heats the stove and stones, which then release heat into the room.
Heating performance depends more on factors such as:
- the size of the sauna
- insulation
- the amount of glass
- stove output
- ventilation
- chimney performance
- the quality of the firewood
A correctly sized internal or external wood-burning stove can provide excellent sauna heat and steam.
Which Option Is Better for a Private Sauna?
For many private outdoor saunas, an internally fired stove is the simplest and most economical choice.
It offers a traditional experience and works particularly well where the sauna is used by a family or a small group.
An externally fired stove may be preferable when you want to keep firewood and ash outside or manage the fire without entering the sauna.
Which Option Is Better for a Commercial Sauna?
For commercial saunas, an externally fired stove is often the more practical solution.
Staff can add firewood and control the fire without entering the sauna or interrupting customers. This is particularly useful when the sauna operates for several hours or is used by changing groups throughout the day.
External-Fire Stoves for Polaris Sauna Models
Polaris Sauna can offer externally fired wood-burning stoves with most of our outdoor sauna models.
The available options depend on the sauna size, wall construction, bench layout and selected stove.
Simply mention that you are interested in an externally fired stove when contacting us. We will confirm the options for your preferred sauna model and recommend the most suitable stove and layout.
Choosing the Right Wood-Burning Sauna Stove
Choose an internally fired stove if you prefer a simple, traditional and cost-effective solution.
Choose an externally fired stove if you want a cleaner interior, easier fire management or a practical setup for commercial or frequent use.
Polaris Sauna supplies outdoor saunas with both internal and external wood-burning stove options throughout Ireland. Contact us to discuss your project and find the right configuration for your space.
