Inside Saunum’s Heater Factory: Steel, Data Loggers, and Which One Belongs in Your Sauna
We went to Tallinn to watch the heater we keep recommending get built, and to settle which model fits which sauna.
We spend a lot of time talking about wood. Thermo-modified aspen, how a bench feels on the back of your legs, why one wall panel cups and the one next to it doesn’t. So it was a little humbling to walk through Saunum’s factory in Tallinn this September and meet people who nerd out about metal the way we nerd out about wood.
The metal
The air blending module, built by hand. Photo: Saunum.
The steel inside a Saunum heater is Magnelis, a zinc-aluminum-magnesium coated steel you’d sooner find on solar frames or at sea, with three times the corrosion protection of galvanized. A sauna heater lives in steam, and a Saunum can live in salt air if you run the salt spheres, so that choice isn’t for show.
The heating elements are visibly thicker than the ones we’re used to seeing. More surface area means the element moves heat into the stones faster and doesn’t have to run as hard to do it, and an element that isn’t straining is an element that lasts.
Seventeen seconds inside the heater assembly store. Video: Sauna Marketplace.
The contactor boxes are built like industrial gear. Nothing cheap in there, and the people who build it care about every cable and every connection. We walked the line.
And it’s not for nothing.
Don’t settle for a hot room
Everything wrong with an ordinary sauna is up there. Photo: Saunum.
Every sauna stratifies. It’s pure physics: hot air rises and sits trapped at the ceiling, cooler air pools at the floor. Your thermostat reads one spot on the wall, so set a traditional sauna to 176F and Saunum’s own measurements put it at about 226F at head height and about 81F at your feet.
You know this room even if you’ve never measured it. Your head cooks, breathing gets hard, and your feet are still cold. It’s why you’ve crouched forward on the top bench to save your face, and it’s why so many people leave early and call the sauna “too intense” when the real problem is that the heat was in the wrong place.
What the fan actually does
The fan that does the work, going into its housing. Photo: Saunum.
Saunum’s answer is a patented air blending system inside the heater. It pulls the scorching layer down off the ceiling, blends it with the cooler, fresher air off the floor, and sends it back out low, where people sit. Same rocks. Same steam. Same room, now about 196F up top and 149F at the floor. Two thirds of the gap, gone.
Your feet notice first. The floor stays warm, breathing gets easier, and because breathing is easier you can throw more water, stay in longer, and walk out recharged instead of wrung out. The way we put it on calls: it raises the bench level. The lower bench stops being the lesser bench. You stop suffering, and your core still gets hotter.
How the blending works, in two minutes.
Owners describe it better than we do.
I used to lift my feet up because of that. Until I had my Saunum heater installed.
Aivar, Saunum Air owner, in his review on saunamarketplace.com
Friends who normally would not use a sauna actually enjoyed ours and had no problems breathing or staying comfortable. You don’t need to build an upper bench with the fan system.
Bob, Saunum Air 7 kW owner, in his review on saunamarketplace.com
Who it’s for
The showroom sauna at the factory, heater in its slatted surround. Photo: Sauna Marketplace.
With the push of a button a Saunum heater can create the most adaptable sauna experiences in the world. That’s why we recommend it to the guy whose wife doesn’t think she likes a sauna (a mild session on fan speed 3 wins her over every time) and to the most obsessive connoisseur of heat, on the same day. It’s the best for both.
The connoisseur gets his sauna too. Turn the fan off and you have a classic, hard-hitting electric sauna.
With the fan on, your body can get very hot but the heat feels less harsh. With the fan off you have a classic sauna.
Mark, Saunum Air owner, in his review on saunamarketplace.com
Mark’s trick is to run the fan for a few minutes after preheating so the whole room comes up to temperature, not just the top half. That is exactly what the manual asks for: fan off while the room heats, then pick one of the three speeds. One of us runs a Saunum at home.
Our Saunum Air demo, fan off and fan on.
The lab
The test lab: sensor wiring on the wall, live temperature curves on the screen. Photo: Saunum.
And Saunum can prove it all. The same Tallinn site holds the most sophisticated sauna research setup in the world: three testing labs under one roof, including a UL-validated one. Another has movable walls, so they can change the size of the sauna on the fly, and it’s wired with hundreds of data loggers that map every small shift in airflow and heat. Across town they run a dedicated sauna laboratory at Tallinn University, where researchers are in it daily.
The electronics lab, where controllers and power units get tested. Photo: Saunum.
The numbered jig that puts temperature sensors in the same spots every time. Photo: Sauna Marketplace.
The movable room was running beautifully until our host opened the door to show us inside and threw off the run. Sorry. The world will have to wait another day.
Which Saunum is yours
Every model runs the same air blending. The differences are room size, how the blending is plumbed, and how hard the heater will be worked. Size from adjusted room volume, not the tape measure. Saunum’s own rule is to add 3 cubic feet to the room for every square foot of glass, tile, brick, concrete, or stone, and if that lands you between two sizes, take the bigger one. A Saunum needs more power per cubic foot than an ordinary heater because it’s heating the bottom of the room too, and undersizing it is the one way to make it disappoint you. If you’re not sure, send us the dimensions and what the walls are made of and we’ll size it with you.
Small rooms, up to about 300 cubic feet: the Saunum Air
The 5 kW covers roughly 106 to 212 cubic feet and the 7 kW 177 to 318. Closed black basket or open stainless basket, a chimney that runs to the ceiling to pull the hot layer down, and the heater Bob and Mark are describing above. If you’re building a compact home sauna or a barrel, start here.
Most home builds, 210 to 565 cubic feet: the Saunum Air Perfect
The newest one, and the cleanest version of the idea. Two stacked rock baskets with the fan pulling ceiling air through the core of the heater and pushing the blend out at floor level, so there’s no chimney to route. It comes as 7 kW (210 to 350 cubic feet) or 10 kW (318 to 565), needs 77 inches of ceiling and about 3 inches of clearance around it, which is why it’s our answer for corners and tight rooms, and it won the Golden Wave award for technical innovation at Interbad in 2024. It gets to the same result in a more elegant way and is easier to install and service. If you like to suffer, this is not your heater.
Big rooms, commercial, or a sauna that runs all day: the Saunum Air L
10, 13, or 15 kW, covering roughly 283 to 812 cubic feet. This is the commercial-grade one: close to 190 pounds of stone, the rock basket top at 34 inches so the blending happens closer to where you sit, and the build quality that started this whole post. If you run a gym, a spa, a rental, or you simply want the heaviest steam Saunum makes, this is it.
Already have an electric heater you like: the Saunum AirSolo
Not a heater. It’s the blending system on its own, 120 volt, mounted on the wall or built into it, and it works with any electric sauna heater. If your sauna is built and the problem is the cold floor, this is the fix that doesn’t start over.
Want the whole sauna delivered: the SaunaLife G6 or the Saunum AirCube
Both are factory-built cabins with a Saunum heater already in them. The G6 is Saunum’s own Classic cabin, sold here under the SaunaLife name, and it’s the fastest path from “we should get a sauna” to sitting in one.
A Saunum cabin sauna on a golf course outside Tallinn. Photo: Sauna Marketplace.
Every Saunum we sell goes out with the AirIQ Wi-Fi controller (schedules from your phone, three fan speeds), stones selected by Saunum, the Himalayan salt spheres, an external temperature sensor, and the prewired power box that makes the electrician’s day easier. They ship from greater Chicago, with US-based support from people who know these heaters.
The Himalayan salt spheres that ride inside every Saunum. Photo: Saunum.
What’s next
Walking the floor in Tallinn. Photo: Saunum.
We also walked the prebuilt sauna factory and saw the newer Saunum Air heaters, including the one feature you’ve asked us for more than any other. Those get their own posts.
Thank you to the whole Saunum team for opening the doors, even if it cost you a data set.
We know more about these saunas than anyone outside of Europe, and we just came back from the building where they’re made. If you’re deciding whether a Saunum belongs in your build, or which one, head on over to Saunum on Sauna Marketplace or call us at (844) 565-1113. We’re happy to talk you through it.
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