Guide
Barrel sauna heater size
Barrel saunas are small inside but lose heat through thin staves, so the heater needs more power than the volume alone suggests.
Why barrels need more power
A barrel's walls are usually a single layer of wood about 40 mm (1.5 in) thick with no insulation. That wall has several times the heat loss of an insulated sauna wall. Outdoors the room also starts cold, sometimes below freezing, so the heater has more temperature to climb.
Typical sizes
| Barrel | Volume | Recommended | Warm-up from 5 °C |
|---|---|---|---|
| 6×4 ft barrel | 113 ft³ | 6 kW | 55 min |
| 6×6 ft barrel | 170 ft³ | 8 kW | 52 min |
| 6×8 ft barrel | 226 ft³ | 9 kW | 58 min |
| 7×8 ft barrel | 308 ft³ | 12 kW | 52 min |
| 7×10 ft barrel | 385 ft³ | 15 kW | 48 min |
Figures assume a glass door, outdoor location and a starting temperature of 5 °C (41 °F).
Ways to heat faster without a bigger heater
- Keep the vents nearly closed during warm-up and open them for bathing.
- Add a heater with a larger stone mass only if you can wait longer; heavy stones store heat but take longer to warm.
- An insulated door and a smaller glass area make more difference than one size step on the heater.