Narvi Black 20 Through-the-Wall Wood-Burning Sauna Heater

Narvi Black 20 Through-the-Wall Wood-Burning Sauna Heater provides power, precision, and refined Finnish craftsmanship.  

Offering robust performance, enduring quality, and timeless elegance, the Narvi Black 20 through-the wall sauna heater is a masterclass in engineering. Its large stone compartment ensures optimal heat retention and a long, consistent "löyly," while the generously sized fire grate spans the full base of the heater, maximising combustion efficiency. Secondary air is carefully directed beneath the ash pan, further enhancing burn performance for cleaner, more efficient heating. 

The firebox is built for durability, with a 10 mm-thick stainless steel roof capable of withstanding years of intense use. The glazed cast-iron door not only showcases the warm glow of the fire but also helps maintain a steady flame, adding ambience to the adjacent room. 

With adjustable legs for effortless installation and a through-the-wall configuration, the Narvi Black 20 is conveniently loaded from outside the sauna, keeping your sauna clean and uncluttered while adding warmth to the adjoining space. 

For those seeking both substantial heating capacity and elegant Nordic design, the Narvi Black 20 is a refined yet powerful choice.  

Please note that the flue kit and sauna stones are to be purchased separately

We recommend the Kota Insulated Steel Flue / Chimney Kit.

This heater requires 60kg of sauna stones. We recommend using 10-15cm Olivine Diabase or Vulcanite Sauna Stones for optimal performance.

Warranty

The warranty on this Narvi Sauna Heater is 2 years in private use.

About Narvi Oy

Browse our wider Narvi sauna heater collection. 

Product Disclaimers

All Narvi sauna heaters are CE tested and bear the Finnish Key Flag Symbol. This is awarded to sauna heaters that are made and designed in Finland, where over 95% or more of the production must be within Finland itself. There are many brands that claim to be made in Finland but are actually made in the Far East or Russia and merely assembled or labeled in Finland. Watch out for these symbols as a mark of an authentic, Finnish-made, safe, quality product:

As part of Finnmark Sauna's Endurance Ethos, we only deal in products that are market leaders in quality. We commit ourselves to search exhaustively for the highest quality authentic Finnish sauna products.

Please note, we recommend that sauna heaters should be installed by a suitably qualified builder/plumber/fitter. Finnmark Limited accepts no liability for loss or injury caused by the incorrect installation or misuse of your sauna heater. Please Contact Us if you require information on our recommended fitters.

Christmas and New Year's Shipping Update (Updated 2nd December 2025)

Please note the following changes to our pallet shipping and DPD delivery service on parcel orders over the Christmas period.

Our warehouse is fully closed for operation over the following days: Wednesday 24 December, Thursday 25 December, Friday 26 December, Wednesday 31 December and Thursday 1 January.

Orders requiring a pallet

The last dispatch date for orders requiring a pallet is Friday 19th December 2025. Pallet orders dispatched on this day must be booked and signed for with one of our sales team in advance.

Please note:

• Pallets dispatched on 19th December will be delivered on either 22nd or 23rd December, depending on your postcode
• We strongly advise against booking deliveries to the Highlands or Channel Islands close to the 19th December, as these may be held at the hub over the festive period
• There may be limited availability for pallet shipping on this day and we cannot guarantee that available slots remain

We will commence our regular pallet shipping service on Monday 5th January 2026.

If you have any questions about your pallet order, please get in touch with our Sales team: +44 (0) 20 8050 2895 or email info@finnmarksauna.com

Small Parcel Orders

DPD will deliver as normal up to and including Tuesday 23rd December 2025. Our daily cut-off for next day delivery is 2pm, with orders placed by 3pm on Tuesday 23rd December being our final dispatch before Christmas. Whilst we use a DPD Next Day delivery service, this is not a guarantee - please order earlier to avoid disappointment.

Limited dispatch service: We will dispatch DPD orders on Monday 29th December and Tuesday 30th December only during the festive closure period.

We will commence our regular delivery service on Monday 5th January 2026.

*Estimated delivery times are applicable to the UK mainland only (excludes Highlands and Islands). Additional delays and charges will be required for Non-UK Mainland and Highlands and Islands deliveries.