Rated for a bigger room: Kuuma Classic Legacy (Medium)
Kuuma rates it for 512–780 ft³ (about 14.5–22.1 m³, our conversion); Narvi rates the Stony 20 for 8–20 m³ (about 283–706 ft³, our conversion).
Narvi Stony 20
A wood-burning sauna stove from Narvi, rated by the maker for 8–20 m³ (about 283–706 ft³, our conversion). Every figure below is Narvi's own, linked to where it is published.
See it at NarviSpecifications published by Narvi (8)
- Room size it is rated for
- 8–20 m³ (about 283–706 ft³, our conversion)Narvi Stony 20 - Narvi Oy
- Fuel
- Wood-burningNarvi Stony 20 - Narvi Oy
- Stone capacity
- 210 kgNarvi Stony 20 - Narvi Oy
- Dimensions
- H 81 cm x W 52 cm x D 55 cmNarvi Stony 20 - Narvi Oy
- Weight
- 70 kgNarvi Stony 20 - Narvi Oy
- Water tank
- Chimney water tank accessory (22 l / 30 l)Narvi Stony 20 - Narvi Oy
- Flue / chimney diameter
- 119 mmNarvi Stony 20 - Narvi Oy
- Warranty
- 2 years (private use); 1 year (non-private use)Limited Warranty - Narvi Oy
As published by Narvi, read on 2026-09-23. Makers revise their products; check Narvi's current specification before you buy. Figures marked "about" are Saunakivi's unit conversions of the maker's figure.
Before you buy
- Room size. Our heater sizing guide explains how makers adjust the rated room size for glass and uninsulated walls.
- Wood or electric. Our wood vs electric guide sets out what each needs to install.
If you are looking for more
A longer stated warranty, on at least part of the product: HUUM HIVE Flow
HUUM states: 3 years (private use); 1 year (commercial use). Narvi states for the Stony 20: 2 years (private use); 1 year (non-private use).
Compare it with
Stony 20 vs Pro 20 ES wood-burning heater
Side by side with the Harvia Pro 20 ES wood-burning heater. Both are wood-burning stoves, and the room sizes their makers rate them for overlap.
Stony 20 vs HIVE Flow
Side by side with the HUUM HIVE Flow. Both wood-burning stoves are rated by their makers for at least some of the same room sizes.
Stony 20 vs Low Profile (Medium)
Side by side with the Kuuma Low Profile (Medium). These wood-burning stoves carry maker room-size ratings that share part of the same range.
Other wood-burning stoves
Harvia M3 wood-burning heater
Harvia · wood-burning · 16.5 kW · rated for 212–459 ft³ (about 6–13 m³, our conversion)
Harvia Pro 20 ES wood-burning heater
Harvia · wood-burning · 24.1 kW · rated for 283–706 ft³ (about 8–20 m³, our conversion)
Harvia Legend 150 wood-burning heater
Harvia · wood-burning · 16 kW · rated for 6–13 m³ (about 212–459 ft³, our conversion)
HUUM HIVE Wood 13
HUUM · wood-burning · 13 kW · rated for 6–13 m³ (about 212–459 ft³, our conversion)
HUUM HIVE Flow
HUUM · wood-burning · 9.8 kW · rated for 8–18 m³ (about 283–636 ft³, our conversion)
Kuuma Classic Legacy (Medium)
Kuuma · wood-burning · rated for 512–780 ft³ (about 14.5–22.1 m³, our conversion)
Stony 20: questions answered from Narvi's specification
What size of sauna room is the Stony 20 for?
Narvi rates it for 8–20 m³ (about 283–706 ft³, our conversion). See our heater sizing guide for how makers adjust that figure for glass and uninsulated walls. Related question: Wood-burning sauna stoves: which room size is each rated for?
Source: Narvi Stony 20 - Narvi Oy
How many stones does the Stony 20 hold?
Narvi lists a stone capacity of 210 kg.
Source: Narvi Stony 20 - Narvi Oy
What flue size does the Stony 20 need?
Narvi lists 119 mm. Flue and chimney work should follow the manual and local code.
Source: Narvi Stony 20 - Narvi Oy
Can the Stony 20 heat water?
Narvi lists: Chimney water tank accessory (22 l / 30 l).
Source: Narvi Stony 20 - Narvi Oy
What warranty does Narvi give on the Stony 20?
Narvi lists: 2 years (private use); 1 year (non-private use).
Source: Limited Warranty - Narvi Oy
More from Narvi: all Narvi products on Saunakivi.
Sources
- Narvi Stony 20 - Narvi Oy — Narvi
- Limited Warranty - Narvi Oy — Narvi