Heater database · Kastor
Kastor Karhu 40
Kastor Karhu 40 is a wood-burning stove rated for sauna rooms of 1059–1413 ft³ (30–40 m³). Classic Finnish steel stove for big saunas; water-tank and through-wall versions.
WoodWood-burning stove
1059–1413 ft³rated room · 30–40 m³
121 lbstones · 55 kg
15 kWnominal output
Rooms it fits
Indoor rooms with insulated walls, a 7 ft ceiling and a glass door, which counts extra. Wood stoves are rated by room volume, not by kW. For your own room, glass, masonry or log walls, use the calculator.
| Room | Counts as | Fit |
|---|---|---|
| 4 × 5 ft | 199 ft³ | Too big for this room |
| 5 × 5 ft | 234 ft³ | Too big for this room |
| 5 × 6 ft | 269 ft³ | Too big for this room |
| 6 × 6 ft | 311 ft³ | Too big for this room |
| 6 × 7 ft | 353 ft³ | Too big for this room |
| 7 × 8 ft | 451 ft³ | Too big for this room |
| 8 × 8 ft | 507 ft³ | Too big for this room |
| 8 × 10 ft | 619 ft³ | Too big for this room |
Source
Rated room range and stone load from Kastor's product information, checked October 2026. Ranges are the manufacturer's calculated room volumes; check the manual for safety distances, and have a licensed electrician make the connection.