Heater & Controls
The heater drives almost every other decision in your sauna build — room sizing, electrical spec, clearances, ventilation placement. Choose it before you finalize anything else, and get the full installation requirements in writing before you buy.
Sizing to your room
Electric sauna heaters are rated in kilowatts for specific room volumes (cubic feet). An undersized heater won't reach temperature; an oversized one wastes energy and overheats the room. As a rough guide:
| Room volume (cu ft) | Heater size (kW) |
|---|---|
| Up to 150 cu ft | 3–4.5 kW |
| 150–300 cu ft | 6 kW |
| 300–500 cu ft | 8–9 kW |
| 500+ cu ft | 10.5–12 kW |
Always verify against your specific heater manufacturer's sizing chart — these ranges are approximate and vary by brand and room construction.
Heater clearances
| Surface | Typical minimum |
|---|---|
| Side walls | 4–6″ |
| Back wall | 2–4″ |
| Ceiling | 12–18″ |
| Bench | 18–24″ |
Always follow your specific heater manufacturer's requirements — these vary by model and override any general guidance.
Stones
Use only the manufacturer-specified sauna kiuas stones. River rocks or random stones can crack or explode when heated — a serious safety hazard. Stones are typically purchased separately from the heater and need to be replaced every few years as they degrade.
Control units
Most electric sauna heaters use a separate control unit for temperature and timer settings. Some control units — including the Xenio — require an electrician with specific prior installation experience. This is not always disclosed at the point of sale. Ask before you buy.
Controls and thermostat must be rated for sauna use or installed outside the sauna. Never install standard electrical controls inside the hot room.
- Exact voltage, amperage, and wire configuration — including whether a neutral wire is required
- Whether the control unit requires a specialist installer
- Minimum clearances to all surfaces
- Approved stone type, size, and quantity
- Warranty terms and service availability in your area