Harvia

Harvia Pro 20 SL 24.1kW Through-Wall Wood Burning Sauna Stove | WKPR20SLM

Harvia Pro 20 SL 24.1 kW wood-burning sauna stove whose fire chamber passes through the wall, loaded from the next room; for 283–706 cu ft saunas

$1,781

$2,099

Save $318

Fire chamber passes through the wall: wood and ash stay outside the sauna
Up to 88 lb of 4–6" stones
Top 4.5" chimney connection

The Sauna Mastery Protocol Digital Guide

$49 FREE

Full-Value Freight Protection

$299 FREE

Perfect for sauna rooms from 283 - 706 ft³

Select Stones

Required for Operation

Harvia Split-Face Olivine Diabase Sauna Heater Stones 4-6" / 44lbs | AC3020 | 2 Boxes
$124

Select Chimney Kit

Required for Operation

Harvia Sauna Stove Chimney Kit | WHP1500 | Stainless Steel
$1,487
Harvia Sauna Stove Chimney Kit | WHP1500 | Black
$1,578

Select Add-Ons

Harvia Protective Sheath | WL550
$513
Harvia Protective Bedding SM
$316
Harvia Stainless Steel Water Tank Heater | WP220ST
$727
Harvia Pipe Adapter | WZ115155
$105
Harvia One-Sided Protective Sheath, 20 Series | WL500
$224

Quantity

Secure checkout
30-day return window*
2-year manufacturer warranty

*Eligible returns must be requested within 30 days of delivery. Restocking and freight charges apply, and some items are final sale. See the Refund Policy.

In stock — estimated delivery in 7–12 days

Curbside freight delivery by appointment; an adult must sign for the shipment.

Description

What is the Harvia Pro 20 SL wood-burning sauna stove?

The Harvia Pro 20 SL (WKPR20SLM) is a 24.1 kW wood-burning sauna stove for sauna rooms of 283 to 706 cu ft whose fire chamber passes through the sauna wall, so the fire is lit and fed from the room on the other side of the wall. It stands on adjustable legs, has a graphite-black painted steel casing, a glass door and an ash box on the loading side, holds up to 88 lb (40 kg) of 4–6" stones, and connects to the chimney at the top only, through a 4.5" (115 mm) opening. It burns firewood and needs no electrical connection.

The Harvia Pro 20 is the same stove loaded from inside the sauna, with a top or rear connection. The Harvia Pro 36 Duo is the larger through-wall stove, at 31 kW, and the Harvia wood-burning stove collection has every Harvia wood-burning stove Topture sells.

Harvia Pro 20 SL key features

24.1 kW for sauna rooms of 283–706 cu ft (8–20 m³)
Fire chamber passes through the wall: loaded from the next room
Up to 88 lb (40 kg) of 4–6" stones
Top chimney connection only, 4.5" (115 mm)
Graphite-black painted steel casing, glass door and ash box
Takes firewood up to 15.4" (390 mm) long
CE marked (EN 15821)
2-year manufacturer warranty

Specifications

Does the Harvia Pro 20 SL fit my sauna?

The Harvia Pro 20 SL heats sauna rooms of 283 to 706 cu ft (8–20 m³). Harvia's manual adds 1.2 m³ for every square meter of uninsulated brick, glass block, glass, concrete or tile wall, about 3.9 cu ft per sq ft, and a glass door counts: its example is a 10 m³ room with a glass door, which needs the output of a 12 m³ room. Multiply the volume of a solid-log sauna by 1.5. The Pro 20 SL needs at least 51.2" (1,300 mm) between the top of the stove and the ceiling. Harvia's data sheet gives a minimum sauna room height of 81.1" (2,060 mm), counted with the legs fully lowered.

Harvia Pro 20 SL specifications

Harvia Pro 20 SL (WKPR20SLM), Harvia manual Y05-1394-1 and data sheet WK200SL
Output	24.1 kW
Sauna room volume	283–706 cu ft (8–20 m³)
Minimum room height	81.1" (2,060 mm) (Harvia data sheet), with the legs fully lowered
Top of the stove to the ceiling	51.2" (1,300 mm)
Dimensions	16.9" W × 29.9–31.1" H (430 × 760–790 mm) with the adjustable legs; about 28.7" deep including the through-wall fire-chamber extension
Legs	Adjustable, 0–1.2" (0–30 mm)
Stones	Up to 88 lb (40 kg) of 4–6" (10–15 cm) stones; two 44 lb boxes of Harvia AC3020 cover it
Chimney connection	Top only, 4.5" (115 mm); chimney class T600 with a flue at least 4.3" (110 mm) across
Firewood	Up to 15.4" (390 mm) long, 3.1–5.9" (8–15 cm) across
Materials	Steel; the outer casing is painted graphite black (Harvia); glass door
Electrical connection	None; wood-fired
Certification	CE marked (EN 15821)
Harvia part number	WKPR20SLM (GTIN 6417659005708); earlier item code WK200SL
Warranty	2-year manufacturer warranty; stones are not covered

Installation

How is the Harvia Pro 20 SL installed?

The Harvia Pro 20 SL stands on its adjustable legs with its fire chamber pushed through an opening in a concrete or brick wall. Harvia's manual calls for an opening at least 15.9" (405 mm) wide and 19.1" (485 mm) high from the floor, in a wall no more than 4.7" (120 mm) thick; the opening changes if protective bedding is used. Harvia's manual says all local regulations apply, that the stove is not suitable for a shared flue, that no electrical devices, wires or combustible materials may sit within the safety distances, and that the local fire authorities can give detailed fire-safety requirements. Harvia's installation manual, under Documents, gives the step-by-step installation, the chimney connection details and the wood loads.

Does the Harvia Pro 20 SL need floor protection?

It depends on the floor under the Harvia Pro 20 SL. A bare concrete floor at least 2.4" (60 mm) thick needs no protection. A tile floor needs Harvia protective bedding or similar heat-radiation protection, because the adhesives and waterproofing under tile do not resist the stove's heat. A floor made of combustible material needs the bedding too, plus non-combustible protection in front of the stove door. On the loading side, a combustible floor in front of the stove door needs a non-combustible plate at least 17.7" × 31.5" (450 × 800 mm), as Harvia's manual draws it. Harvia's manual names the WL100 bedding for the Harvia Pro 20 SL. The Harvia WL100 protective bedding (Protective Bedding SM) is sold separately; it does not come with the stove.

Harvia Pro 20 SL safety distances

Keep at least these distances between the Harvia Pro 20 SL and anything that can burn.

Harvia Pro 20 SL minimum safety distances (Harvia manual Y05-1394-1)
Top of the stove to the ceiling	51.2" (1,300 mm)
Sides to combustible material	11.8" (300 mm)
Rear to combustible material	11.8" (300 mm)
Front to combustible material	11.8" (300 mm)
To the masonry wall around the stove	3.9" (100 mm)

Harvia Pro 20 SL with the WL500 (one side) or WL550 (three sides) protective sheath (Harvia manual Y05-1394-1)
Sides	2.4" (62 mm)
Sheath to wall	1.2" (30 mm)

The shorter side distance applies only with a sheath fitted; the one-sided WL500 shortens only the side it covers. Without a sheath, use the first table.

Connecting the Harvia Pro 20 SL to a chimney

The Harvia Pro 20 SL connects at the top only through a 4.5" (115 mm) opening, to a chimney of temperature class T600 with a flue at least 4.3" (110 mm) across; it cannot share a flue with another fireplace. The Harvia WHP1500 chimney kit (sold separately) fits the top opening, and its page gives the roof and clearance requirements. For North American 6" chimney pipe, the Harvia WZ115155 pipe adapter (sold separately) adapts the opening.

Does the Harvia Pro 20 SL need a first firing?

Yes, outdoors if possible. Harvia's manual says to fire the Harvia Pro 20 SL body outside until it stops smoking, then install it, load the stones and heat the sauna once to bathing temperature with good ventilation until any smoke stops.

What's Included

What's in the box with the Harvia Pro 20 SL?

Harvia Pro 20 SL wood-burning sauna stove with its fire-chamber extension, glass door, ash box and adjustable legs
Flange for the wall opening
Flue pipe connector
Soot-opening stoppers
Installation and user manual

What you need separately

Two 44 lb boxes (88 lb) of Harvia AC3020 4–6" stones
A chimney: the Harvia WHP1500 chimney kit in stainless steel or black, or a T600 masonry flue
On a tile or combustible floor: the Harvia WL100 protective bedding (Protective Bedding SM), plus non-combustible protection in front of the door on a combustible floor
Optional: the Harvia WL550 three-sided protective sheath or the Harvia WL500 one-sided protective sheath, which shorten the distances to combustible walls
Optional: the Harvia WP220ST water heater, which Harvia lists for the Pro 20 SL
Optional: the Harvia WZ115155 pipe adapter, for North American 6" chimney pipe

Documents

Harvia Pro 20 Duo, Pro 20 SL and Pro 36 Duo Installation and User Manual

Bathing Brands Harvia Stone Requirements Chart

Warranty

Harvia Warranty

Read the full LIMITED WARRANTY TERMS AND CONDITIONS

Step 1

Size it right

Every heater page lists the exact room size it's rated for, so you can match it to your sauna before you order.

Step 2

Spec your chimney

Through-roof or through-wall, single-wall or insulated, we help you build the right kit for your install.

Step 3

Real löyly

Wood-fired stones make the most authentic löyly — pour water across them and the steam hits the way Finns intended.

WHAT COMES WITH EVERY TOPTURE ORDER

Free Bonuses Included With Your Topture Order

Claim $348 in Free Bonuses Today

BONUS 1

The Sauna Mastery Protocol

The session times, temperatures, and weekly rhythm that turn a sauna into a habit you keep. Covers heat-up protocols and what to expect across your first 30 sessions. Sent to your inbox after purchase.

$49INCLUDED

BONUS 2

Full-Value Freight Protection

Large orders ship fully insured. If freight arrives damaged, Topture helps coordinate the claim and replacement process with the carrier and manufacturer. Proper inspection and damage documentation at delivery are required. Most in-stock orders ship within 2–7 business days.

$299INCLUDED

Retail Price: $2,099

Today's price: $1,781

Choose your options now

We thought about buying a sauna for years and finally did. We absolutely love it, especially in the winter. It’s incredibly easy to assemble with two people the whole family uses it.

Verified buyer

Ordered this sauna fall 2024 and we love it. No better feeling during a Minnesota winter. Lastly, I have to mention the customer service for this purchase has been like no other. Any questions or requests I had were addressed immediately by Topture. I got more than I expected from them and have already recommended them to several people looking for saunas. SO if you're thinking about it, JUST DO IT already..

Verified buyer

Thanks for the great service - greatly appreciated.

Verified buyer

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Freight damage? We help coordinate the claim and replacement process.

STILL UNSURE?

Frequently Asked Questions

What comes with the Harvia Pro 20 SL, and what else does it need?

The Harvia Pro 20 SL ships as the wood-burning stove with its fire-chamber extension, glass door, ash box, adjustable legs and the flange for the wall opening, with Harvia's installation and user manual. It needs no electricity, but it does need 4–6 in sauna stones (two 44 lb boxes of Harvia AC3020 fill its 88 lb stone space), a T600 chimney such as Harvia's WHP1500 kit, and, on a tile or combustible floor, Harvia protective bedding, plus non-combustible protection in front of the door on a combustible floor. None of these come with the stove: Topture offers the stones, the WHP1500 chimney, the WL100 bedding, the WL550 or the WL500 sheath and the WP220ST water heater as options, sold separately.

What size sauna does the 24.1 kW Harvia Pro 20 SL heat?

The Harvia Pro 20 SL is rated at 24.1 kW and heats sauna rooms of 283–706 cu ft (8–20 m³), according to Harvia. Harvia adds 1.2 m³ for every square meter of uninsulated brick, glass, tile or concrete surface, about 3.9 cu ft per sq ft, and counts a glass door: a 10 m³ room with a glass door needs the output of a 12 m³ room. Multiply a solid-log sauna's volume by 1.5. The top of the stove needs at least 51.2 in (1,300 mm) to the ceiling. Larger rooms suit the through-wall Harvia Pro 36 Duo, rated for 494–1,271 cu ft.

What chimney does the Harvia Pro 20 SL need?

The Harvia Pro 20 SL needs a chimney of temperature class T600 with a flue at least 4.3 in (110 mm) across; it connects at the top only through a 4.5 in (115 mm) opening, and Harvia's manual does not allow a shared flue. Harvia's WHP1500 steel chimney kit, in stainless or black, joins the top opening with a smoke pipe cut to length; it suits roofs pitched 10° or more (a flat roof needs the WHM24 rain flange) and is CE marked to EN 1856-1. Keep its insulated casing 3.94 in and its uninsulated smoke pipe 19.7 in from anything that can burn.

How is the Harvia Pro 20 SL installed, and does it need electricity or floor protection?

The Harvia Pro 20 SL stands on adjustable legs and needs no electrical connection. Its fire chamber passes through an opening at least 15.9 × 19.1 in in a concrete or brick wall no more than 4.7 in thick. A bare concrete floor at least 2.4 in (60 mm) thick needs no protection; tile needs Harvia protective bedding, such as the WL100, and a combustible floor needs the bedding plus non-combustible protection in front of the door. Keep the stove 51.2 in (1,300 mm) from the ceiling and 11.8 in (300 mm) at the sides, rear and front from combustible walls; a Harvia protective sheath shortens the side distances. Harvia's manual says local regulations apply and the local fire authorities can advise.

What has to be done before the first fire in a Harvia Pro 20 SL?

The Harvia Pro 20 SL should be fired once before its first sauna, outdoors if possible, Harvia's manual says, until the stove body stops smoking as its protective paint cures. Then install it, load the stones and heat the sauna to normal bathing temperature with good ventilation until any remaining smoke stops. Throw no water on the stones during the first firing, and remove leftover paint with a wire brush and a vacuum cleaner once the stove is cold.

What firewood does the Harvia Pro 20 SL burn, and how hot should the sauna get?

The Harvia Pro 20 SL takes firewood up to 15.4 in (390 mm) long and 3.1–5.9 in (8–15 cm) across. Start with pieces of 3.1–4.7 in (8–12 cm) and refuel with 4.7–5.9 in (12–15 cm). Empty the ash box before each firing and keep the door closed while the fire burns. The Pro 20 SL has no thermostat, so the fire sets the heat: Harvia's rule of thumb is that a sauna over 212°F (100°C) is too hot, and several full loads of wood in a row overheat the sauna, the stove and the chimney and can start a fire.

How do you load and maintain the stones in the Harvia Pro 20 SL?

The Harvia Pro 20 SL holds up to 88 lb (40 kg) of 4–6 in (10–15 cm) stones; two 44 lb boxes of Harvia AC3020 split-face olivine diabase stones fill it. Load them only after the first firing, once the stove is cold, with the larger stones at the bottom: Harvia warns that stones placed wrongly can heat nearby structures to dangerous temperatures even outside the safety distances. Rearrange the stones at least once a year and remove any smaller than 4 in or broken.

What problems do Harvia Pro 20 SL owners run into, and how are they avoided?

Most problems Harvia's manual lists for the Harvia Pro 20 SL trace back to the chimney, the wood or the stones. Smoke in the sauna or no draught points to a leaking flue connection, a cold flue, an extractor fan pulling air, a full ash box, blocked smoke canals or a connection pipe pushed too far into the flue. A sauna that will not heat is usually too big for the stove, has uninsulated walls or is fired with damp wood; stones that stay cool are often too small or broken. A smell on the first firings is the paint curing, and wooden walls darkening over time is normal.

Who makes the Harvia Pro 20 SL, and what is it made of?

The Harvia Pro 20 SL (WKPR20SLM) is made by Harvia, the Finnish sauna manufacturer; Harvia US Inc. is its warrantor in North America. It has a graphite-black painted steel casing, a glass door and an ash box on the loading side, and it is CE marked to EN 15821, the European standard for wood-fired sauna stoves. It measures 16.9 in wide and 29.9–31.1 in high on its adjustable legs, and about 28.7 in deep including the through-wall fire-chamber extension.

What warranty does the Harvia Pro 20 SL have?

Harvia's manufacturer warranty covers the Harvia Pro 20 SL for 2 years of family use. The extra registration year Harvia offers applies to electric heaters only, not to wood-burning stoves, and sauna stones are not covered; the warranty also excludes damage caused by stones Harvia does not recommend. Harvia US Inc. is the warrantor in North America. Topture is an authorized Harvia retailer and assists with troubleshooting and warranty coordination.

How does the Harvia Pro 20 SL compare with the Pro 20 and the Pro 36 Duo?

The Harvia Pro 20 SL is the through-wall version of the Pro 20: the same 24.1 kW and 283–706 cu ft range and 88 lb of stones, but its fire chamber passes through the wall, so the wood, the ash and the glass door are in the next room and the sauna side stays clean. It connects at the top only, while the Pro 20 connects at the top or rear and is loaded inside the sauna. The Pro 36 Duo is the larger through-wall stove: 31 kW for 494–1,271 cu ft, with 132 lb of stones.

Where can you buy the Harvia Pro 20 SL from an authorized dealer?

Topture is an authorized Harvia retailer and sells the Harvia Pro 20 SL on its own, with AC3020 stones, the WHP1500 chimney, the WL100 bedding, the WL550 or WL500 sheath, the WP220ST water heater and the WZ115155 adapter as options. Topture adds Lifetime Expert Support, help with troubleshooting and warranty coordination, free shipping on orders over $200 within the continental US, financing through Shop Pay Installments at checkout, and a 30-day return window.

What does a Harvia Pro 20 SL cost in total, delivered?

The delivered cost of a Harvia Pro 20 SL from Topture is the stove price plus the parts it needs: two boxes of AC3020 stones, a chimney such as the WHP1500 kit, and, on a tile or combustible floor, protective bedding. Topture has free shipping on orders over $200 within the continental US, so a Pro 20 SL order ships free there; Harvia stoves travel on a pallet by freight, with Topture's full-value freight protection. Budget separately for installing the chimney. Compare delivered totals, because some listings price the stove without its stones and chimney. Financing is available through Shop Pay Installments at checkout.

General Topture Questions

Where are you located, and where do you ship from?

Topture is an online retailer serving customers in the contiguous United States. The company is Topture LLC, a Wyoming limited liability company, and its registered business address is 30 N Gould St, Ste N, Sheridan, WY 82801.

Orders ship from manufacturer and distributor warehouses in the U.S. and Canada, and some products ship directly from the manufacturer in Europe. Each product page shows its estimated delivery time.

How much is shipping?

Orders over $200 ship free within the continental United States. Orders under $200 carry a small shipping fee.

Two exceptions: SaunaLife and ThermaSol products carry a freight charge at any order value, and sauna stones ordered without a heater ship at $60 per box because of their weight.

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Do you provide financing?

Absolutely! To view your financing offer, simply select Shop Pay Installments as your payment method at Step 3 of checkout.

You'll need to enter a debit card to receive your offer, but don’t worry—you can still back out before completing the purchase.

How long will it take for my items to arrive?

If your order is in stock, most orders ship within 2–7 business days of purchase. Transit time then depends on the distance from the warehouse and, for freight, on booking a delivery appointment.

For custom, pre-order or made-to-order items, the estimated delivery time frame is listed on the product page. Delivery dates are estimates, so please don't book installation labor until your order has arrived and been inspected.

What happens after I place my order?

As soon as you place your order, you'll receive a confirmation email with your order details—be sure to keep it for your records. Once your order ships, you'll receive another email with tracking information.

For freight deliveries, the carrier will call or text you to schedule an appointment once the shipment reaches their local terminal. Someone needs to be there to inspect the shipment and sign for it. Smaller parcels arrive by UPS or FedEx without an appointment.

Is there a warranty?

Yes. Products purchased through Topture include the applicable manufacturer’s warranty, subject to the manufacturer’s terms. You’ll find the warranty details for each product under the "Warranty" tab on its product page, and we help with troubleshooting and warranty coordination if an issue comes up.

Do you have a showroom?

We don’t have a showroom — we sell online. Our team is available by phone, email and chat to help you compare models, sizes and heaters, and we can send dimensions, installation manuals and electrical requirements before you buy.

Where do you deliver to?

We deliver throughout the 48 contiguous states, with curbside freight delivery for large items. Free shipping and standard rates apply there only. Alaska, Hawaii, Puerto Rico, other U.S. islands and Canada are quoted separately, depending on the brand and model. We can't ship freight or oversized items to P.O. boxes.

Do you ship internationally?

International Shipping

For many products, yes, including to Canada, by custom quote. Email contact@topture.com with the product and your address before you order; availability and cost depend on the brand and model. Any duties, taxes and customs fees are your responsibility.

Shipping to Hawaii, Alaska, and Puerto Rico

Free shipping applies to the continental United States only. Shipping to Alaska, Hawaii, Puerto Rico and other U.S. islands is quoted separately and depends on the brand and model. Email contact@topture.com for a quote before you order.

Your wood burning sauna heater, done the right way.

Fire chamber passes through the wall: wood and ash stay outside the sauna
Up to 88 lb of 4–6" stones
Top 4.5" chimney connection

The Sauna Mastery Protocol Digital Guide

$49 FREE

Full-Value Freight Protection

$299 FREE

Secure checkout
30-day return window*
2-year manufacturer warranty

*Eligible returns must be requested within 30 days of delivery. Restocking and freight charges apply, and some items are final sale. See the Refund Policy.

Harvia Pro 20 SL 24.1kW Through-Wall Wood Burning Sauna Stove | WKPR20SLM