





Cozy Heat OG Thru-Wall 12 Sauna Stove (12 kW)

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- Description
- What's Included
- Required to Operate
- Product Specifications
- Clearances & Safety Distances
- Sizing
- Accessories for This Model
- Installation & Use Notes
- FAQs
- Downloads
The Cozy Heat OG Thru-Wall 12 is a 12 kW wood-burning sauna stove for rooms of 210–423 cubic feet. It holds 175 lb of stones (sold separately), needs no electrical supply, and requires a code-compliant chimney. The firebox extends through the sauna wall, so wood is loaded from the room next door.
Wood-fired sauna stoves create a mild and long-lasting heat. Designed for pouring water over hot stones for an intense steam and a more satisfying sauna experience.
- Smoke gases are 6x cleaner
- Stove utilizes 25%-40% less fuel than comparable sauna stoves
- Boasts minimal safety distances
- Floor mount thru-wall
Outer frame of the heater, Chimney pipe, Heater body, Cleaning hatch, Heater door with glass, Ash box, Installation and operation manual
These are not included. You need them before the sauna will run.
Sauna Stones175 lb capacity. Cozy Heat specifies split-face or rounded stones: 4 boxes of Cozy Stone (split-face, 44 lb each — 176 lb) or 6 boxes of Cozy Round (rounded, 33 lb each — 198 lb). Never fire the stove empty. Chimney
A listed, code-compliant chimney system, plus floor protection where the manual or local code requires it. Cozy Heat supplies no chimney kit — the file lists Harvia chimney kits for this stove.
| Cozy Heat Part Number | COZYOGTW12 |
| Power Output | 12 kW |
| Sauna Room Volume | 210–423 cu ft |
| Stone Capacity | 175 lbs |
| Primary Fuel | Wood |
| Maximum Firewood Length | 12.95" (329mm) |
| Firewood Diameter | 3.15" to 4.72" (80mm-120mm) |
| Flue Connection | Top |
| Color / Finish | Black Steel |
| Material | STEEL |
| Dimensions | 25.78" - 27.36"D x 19.60"W x 27.91"H |
| Weight | 139 lbs |
| Shipping Weight | 315 lbs |
| Installation | FLOOR/THRU-WALL |
| Certification | German BIMSCH certificate |
| Warranty | 2 years (limited) |
| Ships | LTL freight, curbside |
| Made In | Estonia |
Marks as supplied by Cozy Heat: German BIMSCH certificate. Requirements vary by jurisdiction — confirm with your building department and insurer before you install.
The minimum distance to combustible surfaces, as published by Cozy Heat. Measure before you frame the bench.
To the Sides6.69" (170mm) Behind
9.05" (230mm) In Front
19.68" (500mm) Minimum Room Height
72" (1828mm)
These are minimums to combustible material, not recommendations. Your installation manual and local code take precedence, and a solid-fuel appliance normally needs a permit and an inspection in the US.
The Cozy Heat OG Thru-Wall 12 is rated for 210–423 cubic feet.
Measure width × depth × height in feet. Add extra volume for anything that soaks up heat rather than reflecting it — glass, tile, concrete, stone and exposed log all make a room behave larger than its raw measurement. Size to the larger number.
| Model | Output | Room Volume | Stones | Loading |
|---|---|---|---|---|
| OG 12 | 12 kW | 210–423 cu ft | 175 lbs | Inside the room |
| OG 18 | 18 kW | 317–635 cu ft | 240 lbs | Inside the room |
| OG Thru-Wall 12 | 12 kW | 210–423 cu ft | 175 lbs | Through the wall |
| OG Thru-Wall 18 | 18 kW | 317–635 cu ft | 240 lbs | Through the wall |
What Cozy Heat lists for this stove. All sold separately.
Chimney CoverCozy Heat Chimney Cover OG H500, Cozy Heat Chimney Cover OG H700 Sauna Stones
Cozy Stone, Cozy Round Chimney Kit
Harvia Chimney & Assembly Kit, Barrel, Flat Roof — Cozy Heat supplies no chimney system of its own, so the file lists Harvia
- Mount to the clearances published above. They are minimums to combustible material, not recommendations.
- The firebox extension passes through the sauna wall, so wood is loaded from the next room and no smoke, ash or cold air enters the hot room. The wall opening has to be framed to the manual before the stove goes in.
- Confirm your flue diameter and that a top connection suits your build before ordering chimney components.
- A solid-fuel appliance normally needs a permit and an inspection in the US, and your insurer will usually want to see the sign-off.
- Load stones loosely by hand so air moves between them, and re-stack once a year, replacing any that have cracked.
How does the Thru-Wall version work?
The firebox extends through the sauna wall so you load wood from the adjoining room. No smoke, ash or cold air enters the hot room, and you are not stepping over bathers to feed the fire. The wall opening has to be framed to the installation manual before the stove is set.
How many boxes of stones do I need?
The stove holds 175 lb. That is 4 boxes of split-face Cozy Stone at 44 lb, or 6 boxes of rounded Cozy Round at 33 lb. Stones are not included, and Cozy Heat recommends ordering one spare box so you can pick the best-fitting stones.
Is a chimney included?
No. Cozy Heat supplies the stove with its own chimney pipe section, but not a full chimney system. Your supplier file lists Harvia chimney kits for this stove, and they are linked above. A solid-fuel installation normally needs a permit and an inspection.
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