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Topture selects for this collection on three things you can verify on a spec sheet: build materials suited to constant heat cycling, a stone capacity heavy enough to hold temperature through constant door traffic, and — on the electric units — a wiring configuration that matches commercial building power. The wood-fired stoves in the collection answer the same duty question without any wiring at all. The Harvia Club series is a stainless floor-standing line covering 388–989 cubic feet across three outputs — the 10kW suits 388–600 cu ft, the 12.5kW 494–742, and the 15kW 600–989, so specify by room volume rather than by series. The Harvia Virta Pro 20kW is a 208V three-phase unit taking 264 lbs of stone, currently made to order. The HUUM HIVE 18kW covers 636–989 cubic feet per HUUM's own installation manual.
The distinction that matters is not marketing language. A gym or spa sauna runs most of the operating day with the door opening constantly; a home sauna runs a couple of short sessions a week. Residential heaters are not specified for that duty cycle. If you are sizing for a home instead, Topture's full sauna heater range covers residential wattages from 4kW up.
Most commercial sauna installations run 208V three-phase power rather than the 240V single-phase used in homes. It is worth settling before you pick a model, because the three-phase units are separate SKUs.
Residential electric sauna heaters in the United States almost always run 240V single-phase. Commercial buildings are typically served with 208V three-phase, which distributes the load across three conductors instead of one pair. Harvia offers three-phase configurations for this reason: the Club series comes in both 240V single-phase and 208V three-phase, and the Virta Pro 20kW is three-phase. HUUM does not — every HIVE Topture carries is 240V single-phase only, so a building on 208V three-phase service should plan around the Harvia lines rather than assume a HIVE can be configured to match. Do not assume kW alone decides it: the requirement is per model. Topture carries 240V single-phase units all the way up to the HUUM HIVE 18kW, while the Harvia Virta Pro 20kW is three-phase only — so check the specific heater against the specific panel.
Confirm three things with your electrician before ordering: the voltage and phase your panel actually supplies, the available amperage on a dedicated circuit, and whether the run length requires a larger conductor. Topture is not an electrical contractor, and every electric commercial install has to be wired by a licensed one to the NFPA 70 National Electrical Code as adopted locally. Wood-fired installs are governed instead by the solid-fuel and chimney provisions of NFPA 211 and your local mechanical code, which is a separate permit and inspection. Controllers differ too: the Xenio CX30 and CX45 kits carry one part number spanning both configurations, while the CX170 and Virta Combi CX30C are ordered per configuration.
Topture sizes commercial heaters by interior room volume in cubic feet, not by person count. Measure length × width × height of the finished interior, then add an allowance for every square foot of uninsulated cold surface — glass, tile, brick or log. The allowance is not the same for both brands, and each publishes its own. Harvia's rule is to add two cubic feet per square foot of cold surface, excluding the door. HUUM's manual is more conservative: add one cubic metre per square metre, which works out to roughly 3.3 cubic feet per square foot. Use the rule belonging to the heater you are actually buying.
This is worth getting right for a reason beyond performance. HUUM's installation manual states plainly that the manufacturer's warranty is not valid if the heater output does not correspond to the calculated volume of the sauna room — so a room specified above the published range is not merely underpowered, it is uncovered. A full glass front can add several hundred cubic feet to the effective load and routinely moves a room up a heater class. Ceiling height is already captured in the volume, but check the heater's minimum room-height spec separately.
| Heater | Output | Room volume | Power |
|---|---|---|---|
| Harvia Legend 150 | 16kW wood | 212–459 cu ft | Wood-fired |
| Harvia Club (10 / 12.5 / 15kW) | 10–15kW electric | 388–989 cu ft | 240V 1PH or 208V 3PH |
| Harvia Virta Pro 16kW | 16kW electric | 354–918 cu ft | 240V 1PH |
| Harvia Virta Pro 20kW | 20kW electric | 354–1,130 cu ft | 208V 3PH |
| HUUM HIVE 12kW | 12kW electric | 424–636 cu ft | 240V |
| HUUM HIVE 15kW | 15kW electric | 530–812 cu ft | 240V |
| HUUM HIVE 18kW | 18kW electric | 636–989 cu ft | 240V |
| Harvia Legend 240 | 21kW wood | 353–848 cu ft | Wood-fired |
| Harvia Legend 300 | 23.5kW wood | 494–988 cu ft | Wood-fired |
| Harvia Pro 20 | 24kW wood | 283–706 cu ft | Wood-fired |
| Harvia Pro 36 | 31kW wood | 494–1,271 cu ft | Wood-fired |
| Harvia Pro 50 | 40kW wood | 706–1,766 cu ft | Wood-fired |
Undersizing is the more expensive mistake. A heater running at its ceiling all day never recovers between sessions, and the elements fail early. Where a room sits between two ratings, size up rather than down. The 12kW class and the 15kW and larger class cover most gym and spa rooms.
Stone mass is what carries a commercial sauna through constant door traffic. Each time the door opens, the room loses air temperature immediately — but a heater holding several hundred pounds of stone re-radiates stored heat back into the room far faster than the elements alone could reheat the air. In a busy facility that thermal buffer is the difference between a room that holds temperature and one that never quite gets there.
The commercial units Topture carries range widely on this. The Harvia Legend 300 carries the largest load in this collection at 573 lbs, with the HUUM HIVE close behind at 528 lbs — the HIVE 12, 15 and 18 all take the same fill, since the three share a basket. Among the Harvia electrics, the Virta Pro 16kW takes a minimum 200 lbs and the Virta Pro 20kW 264 lbs. The Legend 150 holds 264 lbs, and at the other end the Pro 20 holds 88 lbs. More stone means a longer heat-up and a much longer hold. Topture's wider selection covers every traditional heater that uses rocks, residential models included.
Stones are almost always sold separately from the heater, and on a commercial order they are easy to forget — a HIVE takes 16 boxes, 528 lbs in all, before it can be commissioned. The specification matters as well as the quantity: HUUM calls for round natural sauna stones 2 to 4 inches across, olivine or olivine diabase, and states that defects caused by unsuitable stones are not covered by warranty. Decorative stone is explicitly ruled out, because it stores less heat and fractures, and the fragments block the air holes. Browse the full Harvia Virta range or the Legend wood-burning stoves to compare stone loads directly.
Topture sells both into commercial rooms, and the deciding factor is usually staffing rather than heat quality. Electric heaters run on a timer, need no attendant, and can be locked to a fixed temperature — which is why staffed facilities usually run electric. The Harvia Club series and the HUUM HIVE range are the two lines most commonly specified for staffed facilities.
Wood-fired makes sense in a narrower set of cases: off-grid sites, retreat and lodge settings where tending the fire is part of the experience, and any building where pulling 60+ amps of dedicated service is impractical or expensive. The tradeoff is real — a wood stove needs someone to load it, a chimney and clearance to combustibles, and a longer heat-up than electric. Topture's Harvia Pro stoves run from 24kW up to the Pro 50 at 40kW, which covers rooms to 1,766 cubic feet.
A commercial sauna heater needs a control strategy a home sauna does not, because the people using the room are not the people responsible for it. Topture specifies commercial controllers around three requirements: the control head mounts outside the sauna so patrons cannot alter preset limits, the timer supports a full operating day rather than a 60-minute residential cycle, and the unit fails safe on overheat.
Harvia's Xenio CX30 and CX45 kits cover the Club, Spirit, Cilindro and Virta lines with a single part number spanning both 240V single-phase and 208V three-phase; the CX170 and the Virta Combi CX30C are ordered as configuration-specific part numbers instead. Club 12.5/15kW and Virta Pro 16/20kW installs also need the Xenio power extension unit, sold separately. HUUM's UKU controller covers the HIVE range up to 9kW on its own; the HIVE 12kW, 15kW and 18kW each additionally require the UKU extension box, which is included in Topture's HIVE packages and sold separately for standalone heaters. Controller configuration is worth confirming at the same time as voltage. The full range sits in Topture's heater controls collection.
Topture is an authorized dealer for Harvia and HUUM. Commercial orders differ from residential ones in two practical ways: the voltage and phase must be confirmed before the order is placed because three-phase units are separate SKUs, and controller part numbers change with the configuration.
Facilities pairing a traditional room with an infrared cabin can compare the infrared cabins for paid-use facilities Topture carries — infrared runs on far lower power draw and suits smaller per-session rooms. Every electric heater in this collection must be installed by a licensed electrician to local code, and the wood-fired stoves need a compliant chimney and clearances signed off under the applicable mechanical code. Topture supplies the equipment and specifications, not the installation work.