Choosing a sauna heater: stones, panels and kilowatts
The heater is the part of a sauna that decides how it feels, how quickly it is ready, and how much the electricity bill moves. Two saunas with the same timber can feel completely different because one has a 6 kW traditional heater and the other an infrared panel.
Traditional (electric) heaters
A traditional heater is a box of stones with electric elements inside. It heats the room by convection and radiation, and it produces löyly: water poured on the stones flashes into steam and raises the perceived temperature sharply.
These heaters need a warm-up, commonly 20 to 40 minutes, and they need stones: usually 20 to 40 kg depending on the model. The stones store heat, which is why the room stays warm between sessions.
Infrared heaters
Infrared panels emit radiant heat that warms the body directly rather than the air. They heat up in minutes, use less power, and do not produce steam.
The experience is different: no löyly, lower air temperature, and a warmth that feels like sitting in sun rather than in a hot room. People who dislike the intensity of a traditional sauna often prefer it.
Choosing by room size
| Room volume | Typical electric heater | Notes |
|---|---|---|
| Up to 6 m³ | 3–4.5 kW | Small cabins, one or two users |
| 6–10 m³ | 6–8 kW | The common garden cabin |
| 10–14 m³ | 8–9 kW | Larger cabins, four users |
| 14 m³ and up | 9 kW+ or commercial | Check the circuit capacity first |
Rough guidance only. Glass doors, uninsulated walls and cold climates all push the requirement up.
The electrical question
A 6 kW heater draws roughly 26 amps at 230 V. That is not a plug-in appliance: it needs a dedicated circuit, a suitable breaker and, in most installations, an electrician. Check the supply to the garden before ordering the heater, not after.
Control and safety
Most heaters have an external control panel or a built-in timer. The safety items that matter: a temperature sensor, an overheat cut-out, and a guard around the stones. Check that the model is rated for the room volume rather than the number of seats.
Frequently asked questions
Can I put a traditional heater in a small cabin?
Yes, but oversizing makes the room uncomfortably hot and wastes power. Match the heater to the volume.
Do I need stones?
For a traditional heater, yes. Buy the size the manufacturer specifies; too few stones make it run hot, too many make it sluggish.
Is infrared cheaper to run?
Usually, because it heats the body rather than the air and can run at lower power. The difference depends on how long you sit.
Can I convert a traditional sauna to infrared?
Sometimes, but the room is usually built for the other heat source. Check with the manufacturer before buying panels.
How long does a heater last?
Elements fail first. A well-maintained heater commonly lasts many years; the stones should be checked and replaced when they crumble.
The short version
Traditional means stones and steam; infrared means radiant warmth and no steam. Size the heater to the room volume, check the electrical supply early, and buy stones to the manufacturer’s specification.