The Cozy Heat Quattro Through-Wall Sauna Stove Package combines the four-sided minimalist design and large viewing window of the Cozy Quattro with through-wall installation - the clean-lined four-sided body and its generous glass window face the sauna interior, while the firebox passes through the sauna wall so that wood is loaded, fire is tended, and ash is removed entirely from outside the sauna room. Available in 12kW (210-423 cu ft) and 18kW (317-635 cu ft) with stone style selected at checkout, complete with stones included. The Quattro Through-Wall is the specific model for buyers who want the understated elegance and fire-watching qualities of the Quattro combined with the operational cleanliness of through-wall external firebox loading - and it produces a particularly compelling combination: the large window frames the dancing flames for bathers inside, while all the fire management happens invisibly on the other side of the wall.
The Quattro's large window and through-wall operation - a natural pairing
The Cozy Quattro is defined by two things: its four-sided minimalist body with clean straight lines, and its large viewing window - notably larger than the glass doors on other Cozy models - which makes the dancing flames the focal point of the sauna room from a wide viewing angle. In the Quattro Through-Wall, this large window takes on additional significance. In a conventional inside-loading stove, the firebox door is opened regularly for wood loading and fire management - each opening briefly reveals the firebox mechanics and introduces some disruption to the sauna atmosphere. In the Quattro Through-Wall, the firebox is on the other side of the wall. The large window faces the bathers throughout the entire session, showing only the fire itself, never the mechanics of loading or ash removal. The flames are always visible and always uninterrupted. The large window of the Quattro, combined with through-wall operation, produces a cleaner fire-watching experience than any inside-loading stove can offer.
Through-wall operation - clean interior, undisturbed session
In the Cozy Quattro PKG (inside-loading), wood is loaded through the firebox door that faces into the sauna room. The bather or attendant must enter the hot room and open the door to tend the fire. In the Quattro Through-Wall, the firebox door is on the exterior side of the sauna wall - in the changing room, a utility corridor, or outdoors. Wood is loaded from outside. Ash is removed from outside. No wood chips, bark, or ash on the sauna floor. No smoke entering the room when the firebox door opens. The session continues uninterrupted. The Quattro's large window faces the bathers throughout, showing only the clean view of the fire burning within the four-sided enclosure. This is the most fully realised expression of the Quattro's design intent: the fire as a visual feature of the sauna, not an operational task performed within it.
Same Cozy Heat engineering - 5mm stainless flame cutter throughout
Every technical specification of the Cozy Heat range applies: 5mm stainless steel flame cutter, three-stage combustion with primary, secondary, and tertiary air injection burning the flue gases as a third combustion stage, 25-40% firewood reduction, 73.9% efficiency at 12kW and 81.3% at 18kW, and German BlmSchV DIN EN 13240 Level 2 and EN 15821:2010 certification. A chimney installation is required and sold separately. The wall penetration must be correctly sized and fire-protected, and the full installation must be carried out by a qualified professional. Confirm the sauna building layout supports through-wall installation before ordering.
Wood-burning sauna stove package combining four-sided minimalist design and large viewing window with through-wall installation - available in 12kW (210-423 cu ft) and 18kW (317-635 cu ft), select at checkout. Includes Cozy Quattro Through-Wall stove and sauna stones (stone style selected at checkout). Four-sided body with large viewing window faces sauna interior - fire visible throughout the session. Firebox passes through sauna wall - wood loaded, fire tended, ash removed from outside. Clean interior, bathers undisturbed, uninterrupted fire view. 5mm stainless steel flame cutter. Three-stage combustion - 25-40% less firewood. EN 15821:2010 and German BlmSchV DIN EN 13240 Level 2 certified. 12kW: 73.9% efficiency. 18kW: 81.3% efficiency. No electrical required. Chimney required - sold separately. Wall penetration installation required - by qualified professional. Handmade in Estonia. 2-year warranty.
Package - stove + stones included Four-sided minimalist + large window + through-wall 12kW (210-423 cu ft) or 18kW (317-635 cu ft) Large viewing window - uninterrupted fire view Firebox from outside - clean interior Bathers undisturbed during session Three-stage combustion 25-40% less firewood than comparable stoves 5mm stainless steel flame cutter EN 15821:2010 certified German BlmSchV DIN EN 13240 Level 2 Chimney required - sold separately Handmade in Estonia 2-year warranty
Specifications
Output selection - choose at checkout
| 12kW |
210 to 423 cu ft | Min 265 lbs stones | 73.9% efficiency |
| 18kW |
317 to 635 cu ft | Min 353 lbs stones | 81.3% efficiency |
| Electrical required |
None |
| Chimney required |
Yes - sold separately |
| Stone style |
Selected at checkout |
Design, installation and combustion
| Design feature |
Four-sided minimalist body - clean straight lines, large viewing window |
| Installation type |
Through-wall - firebox on exterior side of sauna wall |
| Stone mass location |
Inside sauna room |
| Firebox door location |
Outside sauna room |
| Combustion stages |
Three-stage: primary, secondary, tertiary |
| Firewood reduction |
25-40% less than comparable stoves |
| Certification |
EN 15821:2010 | BlmSchV DIN EN 13240 Level 2 |
Firebox opening dimensions
| 12kW minimum opening width |
10.0" (255 mm) |
| 12kW minimum floor height |
17.3" (440 mm) |
| 18kW minimum opening width |
12.4" (315 mm) |
| 18kW minimum floor height |
18.5" (470 mm) |
Construction
| Design |
Four-sided minimalist body - large viewing window |
| Flame cutter material |
5mm stainless steel |
| Body construction |
Steel |
| Door / window |
Large glass viewing window |
| Flue outlet position |
Top of stove |
| Origin |
Handmade in Estonia |
Installation requirements
| Wall penetration |
Required - correctly sized and fire-protected |
| Adjacent space required |
Yes - on exterior firebox side of sauna wall |
| Chimney |
Required - sold separately |
| Professional installation |
Required |
| Shared flue system |
Not suitable |
| Firewood |
Dry seasoned hardwood required |
Warranty
| Warranty period |
2 years |
| Overfiring |
Not covered |
| Chimney sweeping |
Required regularly |
What's included
Cozy Heat Quattro Through-Wall wood-burning sauna stove (12kW or 18kW - selected at checkout)
Sauna stones - style selected at checkout (min 265 lbs / 12kW, min 353 lbs / 18kW)
Installation and operation manual
Not included (required for operation): Chimney and flue pipe installation (sold separately); wall penetration installation materials and labour (by qualified professional). Optional: Additional sauna stones.
Why the Cozy Heat Quattro Through-Wall Package stands out
Large window, uninterrupted fire view
The Quattro's large viewing window faces the sauna interior throughout the entire session - and with the firebox on the other side of the wall, it is never opened for loading or ash removal from inside. The fire is visible and undisturbed from the moment it is lit until the end of the session. The most uninterrupted fire-watching experience in the Cozy range, made possible by combining the Quattro's large window with through-wall operation.
Four-sided minimalist elegance
Clean straight lines and understated Nordic minimalism inside the sauna room - the four-sided body recedes as a precise functional form while the large window dominates the visual experience. Suited to sauna rooms where the design aesthetic is restrained and considered: clear-finished pine, bare wood benches, neutral or white walls, no superfluous detail.
Clean sauna interior, undisturbed session
Wood loaded, fire tended, and ash removed from outside without entering the sauna. No wood, bark, ash, or smoke inside. The session continues without interruption. For sauna rooms where cleanliness and session continuity matter alongside the fire-watching experience, the Quattro Through-Wall delivers all three simultaneously.
Traditional Nordic installation, minimalist form
Through-wall firebox loading is the oldest installation principle in Nordic and Baltic sauna culture - the bathing chamber kept clean and separate from the stoke-hole. The Quattro Through-Wall pairs this traditional functional arrangement with the most architecturally restrained form in the Cozy range: four sides, clean lines, and the largest window in the family.
Three-stage combustion - 25-40% less firewood
Primary, secondary, and tertiary air injection burns flue gases as a third combustion stage - 73.9% efficiency at 12kW, 81.3% at 18kW, up to 6x cleaner smoke gases. Certified to Germany's BlmSchV DIN EN 13240 Level 2 and EN 15821:2010. Identical combustion performance to every other Cozy Heat model.
Professional installation required - plan first
The wall penetration must be correctly sized and fire-protected by a qualified professional. A chimney must be installed separately. An accessible adjacent space on the exterior firebox side is required. Confirm the building layout and engage a qualified installer before ordering the Quattro Through-Wall.
About Cozy Heat
Handmade in Estonia - minimalist form, clean operation
Cozy Heat Quattro Through-Wall. Four sides, the largest window, and the fire always visible - wood loaded from outside.
Cozy Heat is an Estonian sauna stove manufacturer. The Quattro Through-Wall is the model for buyers who want the Quattro's large fire-viewing window and minimalist four-sided form inside the sauna room, and through-wall loading's clean operational discipline outside it. The combination is a particularly coherent one: the large window makes the fire the constant visual focus of the sauna interior, while through-wall loading ensures the fire is never interrupted by operational tasks from inside the room. The same 5mm stainless flame cutter, three-stage combustion, and German EN 15821:2010 certification as every Cozy model.
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Complete package - Cozy Quattro Through-Wall stove and stones (style at checkout)
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Large window inside sauna, firebox outside - uninterrupted fire view, clean operation
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12kW (210-423 cu ft) or 18kW (317-635 cu ft) - select at checkout
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Three-stage combustion - 25-40% less firewood, EN 15821:2010 certified
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Professional wall installation required - plan before purchasing
Quattro Through-Wall vs its alternatives
Choosing between the Quattro Through-Wall and its nearest alternatives
Cozy Quattro PKG (SKU 129788): four-sided body with large viewing window, inside-loading firebox - for buyers who want the Quattro's design and fire-watching qualities but load from inside the sauna. Cozy Through-Wall PKG (SKU 129792): through-wall external loading, conventional stove body without the large viewing window. Cozy Quattro Through-Wall (this listing): four-sided minimalist body with large viewing window inside the sauna, firebox through the wall - the specific choice when the large fire-viewing window, the four-sided form, and through-wall clean operation are all wanted together and the building layout supports it. All three share identical technical performance, output levels, stone requirements, certifications, and warranty.
A chimney and correctly installed wall penetration are required. Use only dry, seasoned hardwood. Do not overfire. Sweep the chimney regularly. A qualified professional must carry out the wall and chimney installation.
Manuals and Documents
Warranty
2-year warranty
The Cozy Heat Quattro Through-Wall Sauna Stove is covered by a 2-year limited warranty from the date of purchase. The warranty covers defects in manufacturing and materials under normal use conditions. The warranty does not cover: damage caused by overfiring; failure to use dry, seasoned firewood; failure to regularly sweep the chimney; failure to follow installation requirements including proper wall penetration and chimney installation by a qualified professional; or improper modification of the stove. Proof of purchase from an authorized Cozy Heat dealer is required. We are an authorized Cozy Heat dealer.
