Large Sauna Heaters

Large sauna heater sizing by room volume

Choosing a large sauna heater starts with the room, not the brand. Measure the interior and add the maker's allowance for glass and other uninsulated surfaces.

Harvia, HUUM and Saunum add different allowances. For each square foot of glass, tile, brick or other uninsulated wall, Harvia adds about 3.9 cubic feet (1.2 m³ per m²) and counts a glass door, HUUM adds 3.3 cubic feet (1 m³ per m²) for uninsulated brick, tile or glass, and Saunum adds 3.0 cubic feet for glass, tile, brick, concrete or stone. For log walls, Harvia multiplies a solid-log sauna's volume by 1.5, and Saunum does the same for log, plank or stave walls without internal insulation.

Rule out a model whose printed range stops short of the room's adjusted volume, then compare the rest by supply, stones and control; where the volume falls between two Saunum sizes, Saunum's manuals say to choose the larger heater.

Large sauna heaters by brand: HUUM, Harvia and Saunum

Ten of the large sauna heaters here are HUUM's, nine are Harvia's and one, a package, is Saunum's, and the makers differ in what they build into or around the heater:

• For a steamer in the heater: choose Harvia's Virta Combi, which Harvia rates at 10.5 kW for the heater, with a 2.1 kW vaporizer (steamer).
• For a climate-equalizing module: choose Saunum's Air L package, which Topture lists with the Air L heater and its climate-equalizing module.
• Control settings: Harvia's Xenio and Fenix top out at a 194°F setting; HUUM's UKU can be set up to 230°F (110°C), or 194°F (90°C) with its bench sensor fitted.
• For wood heat: rule out this collection, whose heaters are electric, and compare wood-burning sauna heaters.

Large sauna heater supply and current draw

A large sauna heater's supply and current are set per model in its maker's manual. In the makers' figures on a 240 V supply:

• HUUM: 37.5 amps for its 9 kW models here, up to 75 amps for the HIVE 18.
• Harvia: 43.75 amps for the Virta 10.5 kW connected as one group, and 61.7 amps for the Club 15 kW on single-phase.
• Harvia's Virta Pro 16 kW: 66.7 amps in total, wired as 2 or 4 separate circuits.

The building's supply then narrows the choice of large sauna heater:

• For a 240 V supply: every heater here has a version its maker lists for 240 V.
• For a 208 V three-phase supply: choose a Harvia Club or the Virta or Virta Combi 10.5 kW heater in its three-phase version; Topture's Virta and Virta Combi 10.5 kW packages use the 240 V single-phase models.
• For a HUUM heater on 208 V: choose a CLIFF or STEEL, which HUUM's US manuals rate for 208 V as well as 240 V, and size it from its manual's 208 V figures: the HUUM room sizes given on this page are HUUM's 240 V figures.

HUUM's manual for its UKU control sets two installation conditions: the control goes on a dedicated circuit, and only a licensed electrician may do the electrical work. Your licensed electrician sizes the breaker and wire from the manual that ships with the heater and your local code.

Stone capacity and mounting of large sauna heaters

How much stone a large sauna heater here takes differs widely in the makers' figures, even at one output:

• For a heavy stone load: choose HUUM's STEEL, which holds about 330 lb, the HIVE Mini, which requires 331 lb, or the HIVE, with a stone capacity of 551 lb (250 kg).
• For a smaller stone load: start with HUUM's CLIFF, which holds about 165 lb, or a Harvia heater: Harvia lists 132 lb for the Club, gives the Virta and Virta Combi 10.5 kW a maximum of 154 lb and the Virta Pro 16 kW 200 lb, and gives the Cilindro Half a maximum of 200 lb at 9 kW and 265 lb at 10.5 kW.

Every large sauna heater here stands on the floor, as its maker installs it, on adjustable legs or feet or fixed to the floor with brackets or screws. Harvia also fixes the Cilindro Half to the sauna's structures with a wall-mounting device, and Saunum centres the Air L under a hot-air intake cap in the corner between wall and ceiling.

Large sauna heater controls and Wi-Fi

Every large sauna heater here needs a separate control, sold with it in a package or on its own, and the control depends on the maker:

• HUUM: the UKU runs heaters up to 11 kW on its own, so the HIVE 12, 15 and 18 need HUUM's UKU Extension Box with it; HUUM rates the UKU with the Extension Box for heaters up to 18 kW. The UKU Wi-Fi connects to the HUUM mobile app, and the UKU Local is run from its wall panel only, with no app.
• For a Harvia heater: choose a Wi-Fi control to use the MyHarvia app, a Xenio -XW for the Club and a Xenio -XW or Fenix for the Cilindro Half, Virta and Virta Pro; the Virta Combi takes Harvia's Combi controls, the Xenio Combi CX30C or Fenix Combi FX30C, and the Virta Pro 16 kW on four circuits takes a Xenio CX30 or CX45 plus Harvia's LTY45 power extension.
• Saunum: the Air L operates only with Saunum's Air IQ control, whose app adds remote control over the panel's Wi-Fi; the Air L will not start remotely or at a scheduled time while the control detects an open circuit such as an open sauna door, and before remote or scheduled heating, Saunum's manual says to make sure nothing is on the stones or within the heater's safety distances.

Choose a Wi-Fi control if you want to adjust the sauna from a phone, and the UKU Local if a wall panel is enough. Controls for a large sauna heater bought without a package are listed on the sauna heater controls page; if app control decides it, compare sauna heaters with Wi-Fi control.

Large sauna heaters as packages or on their own

The nine heater listings here ship without sauna stones, and ten of the eleven packages list the heater with a control and stones as one item. The HUUM HIVE 12, 15 and 18 packages here also include the UKU Extension Box. The Saunum Air L package here lists the Air IQ Wi-Fi control with its power unit, door and temperature sensors, plus sauna stones. The Harvia Club 10 kW package's contents are on its product page.

• For one order: choose a package that lists the heater, a control and stones together.
• For a control already in place that suits the heater: choose a heater listing here instead of a package; HUUM's manuals for the CLIFF, STEEL and HIVE Mini also allow other certified sauna-heater controls whose rated output covers the heater. Every heater listing here sells its stones as an add-on, along with the maker's controls for a buyer who has none yet.

Shipping on every large sauna heater here is included within the contiguous United States, and the heaters include the applicable manufacturer's warranty, subject to the manufacturer's terms; each brand's warranty is on the HUUM sauna heaters, Harvia sauna heaters or Saunum page. The rest of buying a heater from Topture is on the sauna heaters page.

Next steps for a large sauna heater: narrower outputs, related heaters or sizing help

With the room's adjusted volume in hand, the next step from a large sauna heater is one of three routes:

• Narrow by output: if the volume points to 12 kW, or to 15 kW and up, compare the 12kW sauna heaters or the 15kW sauna heaters.
• Related heaters: also compare the commercial sauna heaters collection.
• Sizing help: if glass, log walls or the supply leave you unsure, ask Topture's Lifetime Expert Support before you order.

Reviewed October 2026