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Includes

What Is Included

All configurations

Included with purchase

Sauna stove, stove door, ash box, fire chamber extension, installation and operation manual.

Required separately

66 lb of split-face sauna stones (quantity 2 × 44 lb of 10–15 cm stones).

Package contents and sold-separately requirements can vary by selection; use the row for the exact configuration chosen above.

Technical Specifications

Model & Application

Model & Application
Brand	Harvia
Catalog Product	Harvia M3 SL Wood-Burning Sauna Stove \| 16.5 kW Through-Wall Feed (WKM3SL)
Heater Type	Wood-burning sauna stove
Model Number	M3 SL
SKU / Part Number	WKM3SL

Electrical

Electrical
Rated Power	16.5 kW

Dimensions & Weight

Dimensions & Weight
Depth	25" (640mm)
Minimum Host-Room Height	78.74 in
Product Weight	105.8 lbs (48 kg)

Stone Capacity & Performance

Stone Capacity & Performance
Stone Capacity	66 lbs (29.9 kg)

Installation Clearances

Installation Clearances
Ceiling-Clearance Reference Height Above Finished Floor	27.95 in
Ceiling-Clearance Reference Plane	Stove Top
Minimum Ceiling Clearance Above Reference Plane	47.24 in

Included & Required

Included & Required
Included Components	Sauna Stove, Stove Door, Ash Box, Fire Chamber Extension, Installation and Operation Manual
Required, Not Included	66 lbs of Split-Face Sauna Stones (Qty 2 x 44 lbs of 10-15cm stones)

Certifications

Certifications
Certifications & Listings	CE, EAC

Warranty

Warranty
Residential Warranty	Warranty

Use the attached current manual and a qualified installer for final sizing, wiring, clearances, venting, and local-code compliance.

Conflict-free exact-model facts verified from the current manual, manufacturer surface, or exact current distributor record; variation-specific values are labeled.

How It Fits

How This Product Fits the System

What it is used for

A wood-burning sauna heater that heats the room and stone mass for traditional löyly. Treat the stove, chimney, floor protection, clearances, combustion air, ventilation, and stones as one installation system.

What to plan

Size from adjusted sauna volume, including the effect of glass, masonry, and other uninsulated surfaces; do not size from floor area alone.
Model-specific verified values are organized in the Technical Specifications tab; selection-specific values are labeled there.
Match the selected model's power or fuel, voltage, phase, circuit, wire, control, stone, and venting requirements before ordering.
Treat clearances, ceiling reference planes, ventilation, guarding, floor protection, and service access as one room-layout decision.
The current exact-model manual controls final installation. Use the product's Manuals & Documents tab and a qualified installer.

Required separately

These items are identified as operational dependencies, not optional add-ons.

Harvia Sauna Rocks (can only be purchased with heater) Vendor-listed operational dependency; match the exact version and quantity to this selection.

Designed to work with

Exact-family replacements and system components are linked here with their specific use.

Harvia HSP3M Safety Railing for Harvia Spirit | Heat-Treated Birch Part of the same heater/control ecosystem; this does not by itself mean the item is required.
Harvia HL3M Safety Rail for Virta HL110, HL70SA and HL90SA | Wood Part of the same heater/control ecosystem; this does not by itself mean the item is required.

Optional accessories

These are vendor suggestions. A suggestion is not proof of fit or a requirement.

Harvia WZ115155 Wood Stove Pipe Adapter 4.5" Euro to 6" USA Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.
Harvia Chimney Kit in Black or Stainless Steel - WHP4921.3 ft Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.
Harvia M3 Protective Bedding, Black Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.
Harvia WL450 - Protective Shield for M1, M2, M3, and M3 SL Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.
Saunum AirSolo Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.
Harvia WZ Smoke Pipe, 4.6 in, for Wood-Burning Sauna Stoves (7.9 in, 19.7 in, 3.3 ft) Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.
Harvia WHP270 Insulated Smoke Damper for Steel Chimneys, Stainless or Black Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.
Harvia WHM25 Chimney Vapor Barrier Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.
Harvia WZ115030SP Damper Plate for Wood-Burning Sauna Stoves Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.
Harvia WZ020115 Lead-Through Flange for Smoke Pipes Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.
Harvia AC4000 White Decorative Sauna Stones, 2–3.9 in, 22 lb Box (With Heater Purchase Only) Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.
Harvia WP220ST Pipe-Model Water Heater | 22 L Stainless Steel Vendor-listed optional accessory; verify exact-model fit and room layout before adding it.

Other heater options

These are comparison alternatives, not drop-in substitutes.

Harvia M3 Wood Fired Sauna Stove A related heater option, not an interchangeable replacement; re-check sizing, power, controls, clearances, and stones.
Harvia Linear 22 GreenFlame A related heater option, not an interchangeable replacement; re-check sizing, power, controls, clearances, and stones.
Harvia Legend 150 A related heater option, not an interchangeable replacement; re-check sizing, power, controls, clearances, and stones.
Harvia Legend 240 GreenFlame A related heater option, not an interchangeable replacement; re-check sizing, power, controls, clearances, and stones.
Harvia Virta Pro 16 | 240V Single‑Phase Commercial Sauna Heater A related heater option, not an interchangeable replacement; re-check sizing, power, controls, clearances, and stones.
Harvia Club Series A related heater option, not an interchangeable replacement; re-check sizing, power, controls, clearances, and stones.
Saunum Air L Stainless - Heat-Equalizing Sauna Heater with Himalayan Salt A related heater option, not an interchangeable replacement; re-check sizing, power, controls, clearances, and stones.
EOS Mythos S45 Design Sauna Heater | 12 / 15 kW A related heater option, not an interchangeable replacement; re-check sizing, power, controls, clearances, and stones.

Verified model-specific facts are kept in Technical Specifications, while current manuals and support files are kept in Manuals & Documents. If an exact source does not resolve a value or relationship, this page leaves it open instead of borrowing from a neighboring model.

Attachments

Gallery

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Harvia M3 SL Wood-Burning Sauna Stove | 16.5 kW Through-Wall Feed (WKM3SL)

Name: Harvia M3 SL Wood-Burning Sauna Stove | 16.5 kW Through-Wall Feed (WKM3SL) | SaunaMarketplace.com
SKU: WKM3SL
Price: 1416.00 USD
Availability: InStock

The M3 with its fire chamber extended through the wall, so the stove is loaded and lit from the next room. 16.5 kW for sauna rooms of 212–459 adjusted cubic feet, 66.1 lb of 4–6 in stones, 105.8 lb net, top flue connection at 4.6 in. Harvia’s SL instructions call for a minimum 19.7 in safety distance to the front, and the door’s opening direction can be changed.

Build Your Quote:

$1,416.00

Zero Interest Payments:

Pay with HSA/FSA:

Built for these

Harvia Sauna Rocks (can only be purchased with heater)
Required, not included. Harvia's stone chart gives 66 lb of 4–6 in AC3020 for a 16.5 kW M SL, two 44 lb boxes. We recommend an extra box so you can choose stones for fit, form and function. See the full product and build your package →
Harvia WL450 – Protective Shield for M1, M2, M3, and M3 SL
The model-specific sheath. The WKM3SL data sheet gives 9.9 in to combustible material at the sides; our WL450 page publishes B 2 in / C 2 in / D 11.9 in with the shield fitted. See the full product and build your package →
Harvia WP220ST Pipe-Model Water Heater | 22 L Stainless Steel
A 22 L stainless tank that sits on top of the stove with the smoke pipe running through it. Harvia states it is compatible with all wood-heated Harvia stoves except the Harvia 50, and this stove has the top flue connection it needs. See the full product and build your package →
Harvia WZ Smoke Pipe, 4.6 in, for Wood-Burning Sauna Stoves (7.9 in, 19.7 in, 3.3 ft)
Matching 4.6 in flue sections in 7.9 in, 19.7 in and 3.3 ft, the chimney connection diameter on this stove's data sheet. See the full product and build your package →

What’s included

Sauna stove
Stove door
Ash box
Fire chamber extension
Installation and operation manual

Every wood-fired sauna has the same nuisance: the fire wants tending and the hot room is where you are trying to sit still. The SL models solve it structurally. In Harvia’s words, they are “designed for people who want to conveniently heat their sauna from another room or outside the building”, and “the opening direction of the door can be changed, making these heaters even easier to use”. The stove body stays in the sauna; its fire chamber extension passes through an opening in a non-combustible wall so the door lands in the next room.

Installation, in Harvia’s words

“Detach the hinge pin and door from the stove. Push the fire chamber extension through the opening far enough to allow attachment of the door.”
Connected to a Harvia steel chimney: “The nonflammable wall through which the stove is installed must extend up to the roof. NOTE! Does not apply to thin nonflammable wall structures that allow to install steel chimney far enough from the wall (for example Harvia Duo glass wall).”
“The safety distance between the inflammable structures and the chimney outer casing must be minimum 4 in.”
Minimum safety distance to combustible material at the front, for SL models: 19.7 in.
Floor protection: “Floor in front of the stove door is made of inflammable material. Install floor protection made of nonflammable material.”
Place firewood on the grate at the back of the fire chamber: Harvia asks you to avoid burning firewood in the fire chamber extension, and not to use excessively long firewood even though it would fit.
Minimum room height 74.9 in.

Specifications

Spec	Value
Output	16.5 kW
Sauna room size	6.0–42.7 ft³ (212–459 adjusted cubic feet)
Dimensions (W x D x H)	15.4 x 25.6 x 28 in
Net weight	105.8 lb; gross 111.6 lb
Stones	66 lb, Ø10–6 in, two 44 lb boxes of AC3020 cover it
Maximum log length	13.7 in
Flue connection	Top; chimney connection diameter 4.6 in
Clearance, front (SL instructions)	19.7 in to combustible material
Clearance, sides	9.9 in combustible, 4 in non-combustible
Clearance, rear	11.9 in
Clearance, ceiling	47.3 in
Minimum room height	74.9 in
Color	Black
Certification	CE, EAC
GTIN / UPC	6417659001151

Common questions

Do I need to add rocks, or does the stove already come with them?

Sauna stones are not included with the Harvia M3 SL and are ordered separately. Harvia's heater and stone chart calls for a minimum of 66 lb of 4–6 in stones for a 16.5 kW M SL, which is two 44 lb boxes of AC3020, and the WKM3SL data sheet gives the same 66.1 lb at Ø4–6 in. We recommend an extra box, because each natural stone is a different shape and size and the spare lets you choose for fit, form and function. What is in the carton is the stove, the stove door, the ash box, the fire chamber extension and the installation and operation manual.

Often bought with the Harvia Sauna Rocks (can only be purchased with heater)

What customers building this room most often add alongside it.

Best Price and Service Guarantee

Sauna Marketplace offers legendary customer service and support. Odds are you landed here from a referral — because we don’t advertise.

Shop Saunas | Shop Sauna Heaters

Includes