Expert help that stays with you

Whether you’re choosing one component or planning the whole room, small details can become expensive problems once installation begins. We know the products we sell and the questions to ask early, helping catch mismatched components, overlooked requirements, and installation issues while they are still easy to fix.

Our job does not end when your order ships. We stay available through installation and beyond. If something needs attention, we stay involved, work the problem, and help see it through.

We want you to feel good about choosing Sauna Marketplace long after your first session, and confident recommending us to a friend. That standard guides the advice we give, the products we sell, and the way we take care of our customers.

Sauna and heater customers also receive free shipping on sauna accessories for life.

Planning a sauna, or need help with one you purchased from us? Our founders have assembled many of the saunas we sell, visited the manufacturers, and use these products every day. New customers and existing Sauna Marketplace sauna and heater owners can Plan in SaunaDesignPro.

Includes

What Is Included

Includes the product and configuration selected above. Hardware, controls, stones, venting, and accessories are not included unless specifically listed.

See How It Fits for required and compatible products.

Technical Specifications

Model & Application

Model & Application
Brand	Harvia
Catalog Product	Harvia Duo Fireplace and Wood Sauna Stove Combo
Heater Type	Wood-burning sauna stove
Exact Models	PRO 20 DUO: WKPR20DUOS; PRO 36 DUO: WKPR36DUOS

Sauna Sizing

Sauna Sizing
Sauna Room Volume	PRO 20 DUO: 282-706 CU. FT.; PRO 36 DUO: 494-1271 CU. FT.

Fuel & Venting

Fuel & Venting
Fuel	Wood

Dimensions & Weight

Dimensions & Weight
Heater Dimensions	PRO 20 DUO: 17" W × 20" D × 30" H; PRO 36 DUO: 20" W × 31" D × 32" H

Through-Wall Installation

Through-Wall Installation
Wall Opening, Minimum	15.9 in wide x 19.1 in tall from the floor (405 x 485 mm), Pro 20 Duo and Pro 36 Duo. Harvia notes the opening dimensions change if the protective bedding is used.
Wall Thickness, Maximum	4.7 in (120 mm) per the manual text; its Figure 11 table shows 5.9 in (150 mm). Plan on 4.7 in. Concrete or brick.
Non-Combustible Wall Around the Opening, Minimum	Pro 20 Duo: 20.3 in (515 mm) beside the opening, 56.3 in (1430 mm) overall width. Pro 36 Duo: 21.9 in (555 mm) beside, 59.5 in (1510 mm) overall (Figure 11, D and E).
Steel Chimney Note	With a Harvia steel chimney the non-flammable wall through which the stove is installed must extend up to the roof (thin non-combustible partitions such as the Harvia Duo glass wall excepted).

Stone Capacity & Performance

Stone Capacity & Performance
Rated Power	PRO 20 DUO: 24.1; PRO 36 DUO: 31
Stone Capacity	PRO 20 DUO: 88 lbs; PRO 36 DUO: 132 lbs

Included & Required

Included & Required
Required, Not Included	PRO 20 DUO: 88 lbs of Split-Face Sauna Stones (Qty 2 x 44 lbs of 4 to 6 in stones); PRO 36 DUO: 132 lbs of Split-Face Sauna Stones (Qty 3 x 44 lbs of 4 to 6 in stones)

Materials & Finish

Materials & Finish
Construction	Steel with stainless-steel outer casing

Certifications

Certifications
Certifications	CE, EAC

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

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

Through-wall opening: at least 15.9 in wide x 19.1 in tall from the floor (405 x 485 mm) in a concrete or brick wall; plan on 4.7 in (120 mm) maximum thickness (the manual text says 120 mm, its figure table 150 mm). The non-combustible wall must continue at least 20.3 in (515 mm, Pro 20 Duo) or 21.9 in (555 mm, Pro 36 Duo) beside the opening, and with a Harvia steel chimney it must reach the roof.
Size from adjusted sauna volume, including the effect of glass, masonry, and other uninsulated surfaces; do not size from floor area alone.
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.
Follow the current installation manual and use a qualified installer.

Designed to work with

Model-specific replacements and compatible system components.

Harvia HL3M Safety Rail for Virta HL110, HL70SA and HL90SA | Wood Designed for the same heater or control system; confirm compatibility with the selected model.
Harvia HL3S Safety Rail for Virta HL70 and HL90 | Wood Designed for the same heater or control system; confirm compatibility with the selected model.
Harvia SASPO240 Safety Railing for Legend 240 and 300 Wood Stoves Designed for the same heater or control system; confirm compatibility with the selected model.

Attachments

Current Installation Manual - Harvia Pro Duo and SL - June 2026

Current Pro Duo and SL manual recovered from the matching current US source. Exact source bytes and model scope verified by Sauna Marketplace on 2026-08-21.

View PDF Download

Current Data Sheet - Harvia Pro 20 Duo WKPR20DUOS - June 2026

Exact WKPR20DUOS technical data sheet. Exact source bytes and model scope verified by Sauna Marketplace on 2026-08-21.

View PDF Download

Gallery

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Harvia Duo Fireplace and Wood Sauna Stove Combo

The Harvia DUO line is a stunning best-of-both-worlds fireplace and sauna spanning two rooms. It’s the most elegant solution to for through-wall sauna operation.

Wall opening: at least 15.9 in wide x 19.1 in tall from the floor (405 x 485 mm), in a concrete or brick wall; plan on 4.7 in (120 mm) maximum wall thickness.

Build Your Quote:

Price range: $2,871.00 through $3,415.00

Size

Clear

Stones

Chimney Kit

Harvia Stainless Steel Chimney Kit for Flat Roof +$1,433.00

Harvia Wood Pipe Adapter 4.5" Euro to 6" USA +$116.67

Water Tank Heater

Harvia Pro Floor Protector

The Harvia protective bedding is used when a fireplace or stove is installed onto a waterproofed tile or hardwood floor. Made of aluminum-zinc coated steel, painted black.

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Zero Interest Payments:

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What to Expect

Compatibility Check

We look for any issues with your order.

Same Day

Ready to Ship

Warehouse schedules shipment

1 Day

Freight Shipping

Our trusted shipping partners will schedule a delivery time and delivery your package to the ground.

4-14 Days

'Whatever-It-Takes' Support

Unlimited access to tech support from SaunaMarketplace.com and Harvia.

Support Details

This order is fulfilled through our US distribution network. That means you have full access to their top-notch customer service and tech support, as well as SaunaMarketplace.com and Harvia support. We're with you and your contractors until it's operating as it should, no matter what.

Before your order ships, we provide contact information and reference numbers for each.

Warranty 2 Years

Warranty Docs

Setup, Operation, and Maintenance

Harvia Pro Stoves are built with safety in mind. These manuals and documents will help ensure a safe, great performing heater for years to come.

Pro 20 Documents

Manual

Catalog

20 Pro Data Sheet

Harvia 20 Pro Declaration of Performance

Harvia Pro Safety Sheet

Pro 36 Documents

Manual

Catalog

Hariva-PRO36-Accessories Hariva-PRO36-datasheet Hariva-PRO36-DOP Hariva-PRO36-Safety Hariva-PRO36-Spare-Parts

Legend Duo Documents

Legend Manual

Declaration of Performance

Safety Distances

Datasheet

Catalog

Harvia Duo Series: A Fusion of Warmth & Experience

Introducing the Harvia Legend 2-in-1 Stove & Fireplace Heaters: Crafted for those who seek an unparalleled sauna experience, Harvia’s Legend and Pro wood-burning heaters redefine sauna luxury. With its imposing black steel frame, the heater houses a significant volume of stones, ensuring that even at milder temperatures, there’s an abundance of steam. Remarkably, your steam potential lasts long after the fire dims. The unique design places the Harvia Duo fire chamber outside the sauna room, seamlessly installing the heater through the wall. Embodying modernity, the fire chamber is innovatively structured to distribute combustion air efficiently. This not only optimizes burning but also enhances the heater’s lifespan. The innovative design also allows for a more flexible arrangement of the sauna boards due to the protective distances from the burning wood.

Setup, Operation, and Maintenance

Harvia Pro Stoves are built with safety in mind. These manuals and documents will help ensure a safe, great performing heater for years to come.

Expert help that stays with you

Our job does not end when your order ships. We stay available through installation and beyond. If something needs attention, we stay involved, work the problem, and help see it through.

Sauna and heater customers also receive free shipping on sauna accessories for life.

Includes

What Is Included

Includes the product and configuration selected above. Hardware, controls, stones, venting, and accessories are not included unless specifically listed.

See How It Fits for required and compatible products.

Technical Specifications