HUUM · MADE IN ESTONIA

HUUM CORE electric sauna heater

Electric sauna heater, dressed in wood.

A steel core of stone and heat. Finished to match your sauna.

HUUM CORE is a floor-standing electric sauna heater made in Estonia. It comes in three outputs (6.5, 9 and 10.5 kW at 240 V) for rooms of 177 to 566 cubic feet, holds 88 lb of stones, needs only 2 in to combustibles on every side and 43.3 in from its top to the ceiling, and can be built into a bench. Its steel body is finished with alder, aspen or thermo-aspen panels and a black or stainless top rim. It needs a HUUM UKU controller (or another certified controller with a timer) and a licensed electrician.

See HUUM CORE at Sauna Marketplace Plan a sauna around HUUM CORE in 3D

HUUM CORE at a glance

01 Close to the wall

2 in to combustibles on every side. 43.3 in from its top to the ceiling.

02 Built into the bench

Fits a bench seat 32.7 in high or lower. Its top level with the seat or higher.

03 88 lb of stone

2 to 4 in stones around the elements. 99 lb supplied when you add stones.

04 Matched in wood

Alder, aspen or thermo-aspen panels. Black or stainless top rim.

HUUM CORE sizes, room volumes and wiring

HUUM CORE comes in 3 outputs. All of them share one body: 15.16 × 15.16 in and 32.7 in tall on its legs, 41.9 lb without stones, holding 88.2 lb of 2 to 4 in stones. Pick the size by room volume; the output and circuit change with your supply voltage.

CORE 6: Rooms of 177 to 318 cu ft, like 5 × 6 ft with a 7 ft ceiling and a glass door.
CORE 9: Rooms of 283 to 460 cu ft, like 6 × 7 ft with a 7 ft ceiling and a glass door.
CORE 11: Rooms of 354 to 566 cu ft, like 7 × 9 ft with a 7.5 ft ceiling and a glass door.

HUUM CORE at 240 V
Size	Output	Room volume	Current	Breaker	Wire
CORE 6	6.5 kW	177 to 318 cu ft	0 A	30 A	10 AWG
CORE 9	9 kW	283 to 460 cu ft	37.5 A	50 A	8 AWG
CORE 11	10.5 kW	354 to 566 cu ft	43.75 A	50 A	8 AWG

HUUM CORE at 208 V
Size	Output	Room volume	Current	Breaker	Wire
CORE 6	4.8 kW	142 to 248 cu ft	21.63 A	30 A	10 AWG
CORE 9	6.75 kW	212 to 354 cu ft	32.45 A	40 A	8 AWG
CORE 11	7.9 kW	265 to 424 cu ft	37.98 A	50 A	8 AWG

Room volumes are adjusted volumes. Multiply width × depth × height in feet, then add 3.3 cu ft for every square foot of glass, tile, brick or other uninsulated wall. Choose the size whose range covers the total.

Source: HUUM CORE installation and operation manual (US)

For an outdoor sauna, add 10 percent to the volume.

Source: HUUM sauna heater calculator

WHY CORE

A heater that belongs to the room.

Inside, CORE is a steel body that holds the elements and 88 lb of stone. Outside, it wears wood panels that match your walls and benches, so it reads as part of the sauna instead of an appliance in it.

It needs just 2 in to combustibles on every side. HUUM allows it to be built into a bench at full height, as long as its top sits level with the seat or higher and air can still move under the bench.

HUUM CORE with wood panels in a finished sauna beside the bench

CORE in a finished room.

THE STEAM

Quick heat. Gentle steam.

The stones are stacked around the elements and over the top. Ladle water on them and the steam rolls off the stone, not a bare element.

Leave air gaps between the stones around the elements, pack the outer layer close together, and cover the elements completely.

Water poured from a ladle onto the stones of a HUUM CORE heater

Löyly. Water on 88 lb of hot stone.

THE CONTROL

At the door, or from your phone.

CORE is run by a HUUM UKU control system. The Wi-Fi version adds the HUUM app, so the room can be warm when you get home.

The black panel mounts outside the sauna, by the door. Wood and glass faces (glass, mirror, gold) can go inside, away from the heater, with the top edge no higher than 40 in and at least 20 in from the exhaust vent. A glass face is recessed into the wall or mounted on HUUM's surface frame, sold separately.

Person starting a sauna from the HUUM app on a phone

Start it from the HUUM app with UKU Wi-Fi.

Finishes

Every size comes with every panel wood and top rim: 18 combinations in all.

Panel wood

Thermo-aspen: Heat-treated aspen. Warm brown, even grain.
Alder: Honey tone with a soft, fine grain.
Aspen: Pale and clean. The lightest choice.

Top rim

Black: Black cover strips around the stones.
Stainless: Brushed metal cover strips around the stones.

Controller and stones

UKU controller

CORE will not run without one. New Sauna Marketplace UKU packages are guaranteed 4.2 and include the control panel, main module, safety sensor and bench temperature/humidity sensor, and runs every CORE size without an extra box. The black panel mounts outside the sauna; wood and glass faces can go inside.

UKU Wi-Fi, Black: Mounts outside the sauna, by the door. Adds the HUUM app.
UKU Local, Black: Mounts outside the sauna, by the door. No app.
UKU Wi-Fi, Wood: Can mount inside the sauna. Adds the HUUM app.
UKU Local, Wood: Can mount inside the sauna. No app.
UKU Wi-Fi, Glass: Can mount inside, recessed or on a frame sold separately. Adds the HUUM app.
UKU Wi-Fi, Mirror: Mirror glass face. Mounts like the Glass panel. Adds the HUUM app.
UKU Wi-Fi, Gold: Gold glass face. Mounts like the Glass panel. Adds the HUUM app.
I already have one: You own a compatible HUUM UKU controller.

Sauna stones

CORE holds about 88 lb of 2 to 4 in stones. HUUM recommends a specialist to lay them.

3 boxes of HUUM stones: 3 × 33 lb, 99 lb in all. Enough to fill CORE.
I have my own stones: 88 lb of clean 2 to 4 in sauna stones.

In the box

CORE heater body
4 adjustable legs and floor brackets
4 metal shields, 4 cover strips and screws
4 wood panels in your wood, with screws
Installation and operation manual

What you also need

A UKU controller. Required. Add it with the heater, or keep the one you have.
88 lb of sauna stones. Required. Add three 33-lb boxes with the heater, or use your own 2 to 4 in stones.
A licensed electrician. A dedicated 240 V or 208 V circuit, sized in the table above. It feeds the UKU main module, which feeds the heater, and the electrician also runs the UKU 4.2 safety, bench and door sensor cables.
A guard rail (recommended). HUUM recommends one, in a material that stays cool to the touch.

Installation facts

To walls and benches: 2 in on every side Distance to combustible material.Source: HUUM CORE installation and operation manual (US), p. 5
Top of heater to ceiling: 43.3 inSource: HUUM CORE installation and operation manual (US), p. 5
Room height: 80 in minimum 80 to 91 in recommended.Source: HUUM CORE installation and operation manual (US), p. 9
Top bench to ceiling: 44 to 51 inSource: HUUM CORE installation and operation manual (US), p. 9
Heater size: 15.16 × 15.16 × 32.7 in W × D × H on its legs. Same for all three outputs.Source: HUUM CORE installation and operation manual (US), p. 5
Heater weight: 41.9 lb Without stones or panels.Source: HUUM CORE installation and operation manual (US), p. 5
Floor anchoring: Screwed down With the brackets that come with it, on screws at least 1/4 in thick and 1 5/8 in long.Source: HUUM CORE installation and operation manual (US), p. 4
Floor: Tile with dark grout Recommended under and around the heater; stone grit and water can mark lighter floors.Source: HUUM CORE installation and operation manual (US), p. 10
Junction box in the sauna: Waterproof, at most 19 11/16 in off the floorSource: HUUM CORE installation and operation manual (US), p. 7

Keep 2 in from the heater to any wood, 43.3 in from its top to the ceiling, and 44 to 51 in between the top bench and the ceiling. The room must be at least 80 in tall; 80 to 91 in is recommended.

SaunaDesignPro is a planning tool, not the installation authority. Safety distances, heater/chimney clearances, guard or embedding exceptions, ventilation, controller/sensor locations, and electrical wiring, breaker, grounding, GFCI/RCD, and disconnect requirements must be verified against the physical product manuals supplied with the actual equipment at the time of installation by qualified installers, licensed electricians, and the local authority having jurisdiction.

Ventilation

The air in the sauna should change about 6 times an hour. The supply vent is 2 to 4 in across and the exhaust vent 4 to 8 in.

With a fan (mechanical ventilation): supply vent at least 15 3/4 in above the floor, exhaust vent no higher than 23 5/8 in.
Without a fan (gravity ventilation): supply vent no higher than 15 3/4 in above the floor, exhaust vent at least 7 7/8 in higher than the supply and no higher than 23 5/8 in.

Source: HUUM CORE installation and operation manual (US), pp. 10-11

Electrical

A licensed electrician connects the heater.
Fit a breaker that disconnects every pole ahead of the controller.
Use heat-resistant supply cable and crimp the wire ends.
The supply enters through the bottom of the heater. Wire and test it before the panels go on.
HUUM recommends connecting the heater without a GFCI breaker. Follow your local code.
Power runs to the UKU main module first, then to the heater. Mount the module outside the sauna in a dry spot; if it must go inside, no higher than 4 in off the floor and at least 6 ft from the heater, ideally under the bench.

The current, breaker and wire for each size at 240 V and 208 V are in the size tables above.

Warranty

Home use: 3 yearsSource: HUUM warranty terms
Commercial use: 1 year Includes home use over 1,500 hours in 12 months.Source: HUUM warranty terms
Not covered: Heating elements, stones, sensors, accessories HUUM sells the wood panels as accessories. Also void if the heater is the wrong size for the room or the stones are unsuitable.Source: HUUM warranty terms
On delivery: Inspect within 7 days Photograph any visible damage and claim it before you install.Source: HUUM warranty terms
To keep it valid: Licensed install, complete set Heater, controller and stones installed per HUUM manuals by a licensed electrician.Source: HUUM warranty terms

Where to buy HUUM CORE

In the US and Canada, order HUUM CORE from Sauna Marketplace, with the controller and stones you choose on this page in the same cart. Free shipping to the contiguous US. Canada, Alaska and Hawaii are priced at checkout or by quote. The current price is on the store's page.

Building the whole room? The SaunaDesignPro designer plans the walls, benches, wood and heater together and lists the materials.

In the contiguous US you can also talk it through with Ben: a free 30-minute video call with a Sauna Marketplace co-founder.

Outside the US and Canada, buy from a HUUM dealer in your country. Dealers set their own price and delivery.

HUUM CORE at Sauna Marketplace Open the 3D sauna designer Book a Ben: a free call with a Sauna Marketplace co-founder (contiguous US) Find a HUUM dealer

HUUM CORE questions

Which CORE size do I need?

Multiply width × depth × height in feet to get the room volume. Add 3.3 cu ft for every square foot of glass, tile, brick or other uninsulated wall. For an outdoor sauna, HUUM's calculator adds 10 percent more. Then pick the CORE whose range covers the total: CORE 6 for 177 to 318 cu ft, CORE 9 for 283 to 460, CORE 11 for 354 to 566 at 240 V. The sizing tool on this page does the math for you.

Can CORE run on 208 V?

Yes, at lower output. On 208 V, CORE 6 makes 4.8 kW for 142 to 248 cu ft, CORE 9 makes 6.75 kW for 212 to 354 cu ft and CORE 11 makes 7.9 kW for 265 to 424 cu ft. Many apartment and commercial buildings supply 208 V, so ask your electrician which you have.

What circuit does CORE need?

At 240 V: CORE 6 draws 25 A on a 30 A breaker with 10 AWG wire; CORE 9 draws 37.5 A and CORE 11 draws 43.75 A, both on a 50 A breaker with 8 AWG wire. A licensed electrician must make the connection.

Does CORE come with a controller?

No. CORE needs a controller with a timer. HUUM pairs it with the UKU control system; UKU Wi-Fi adds the HUUM app. The UKU handles heaters up to 11 kW, so every CORE size works with it directly. Add one when you order, or choose "I already have one".

How many stones does CORE hold?

About 88 lb of 2 to 4 in sauna stones. Adding stones at Sauna Marketplace supplies three 33-lb boxes (99 lb), so you have a few spare. Wash them, leave air gaps around the elements, pack the outer layer close, and keep the elements fully covered. Too few stones is a fire hazard.

Can CORE be built into a bench?

Yes. HUUM allows CORE to sit inside a bench at its full height, as long as the top of the heater is not lower than the bench surface and air can move freely under the bench. Keep 2 in from the heater to any wood. CORE stands about 32.7 in tall, so the seat it sits in can be no higher than that; in most rooms that is the lower bench or a step.

How tall does my sauna need to be?

At least 80 in. HUUM recommends 80 to 91 in, with 44 to 51 in between the top bench and the ceiling, and 43.3 in from the top of the heater to the ceiling.

Which panel wood should I choose?

Pick the wood that matches your walls or benches. Thermo-aspen is a warm brown, alder is a honey tone, and aspen is the palest. Every wood comes with a black or stainless top rim, at the same outputs.

Is there an all-black CORE?

HUUM makes CORE Black, with a black steel casing instead of wood panels. The CORE on this page is the wood-panel version that Sauna Marketplace stocks. For CORE Black, call Sauna Marketplace at (844) 565-1113.

What does the warranty cover?

HUUM covers CORE for 3 years in a home sauna and 1 year in commercial use. Heating elements, stones, sensors and HUUM accessories (the wood panels are sold as one) are not covered, and the warranty is void if the heater is the wrong size for the room. It needs a licensed electrician and a complete set: heater, controller and stones, installed per HUUM manuals. Inspect the delivery within 7 days and claim any visible damage, with photos, before you install.

Which safety standard does CORE follow?

HUUM builds CORE to EN 60335-2-53, the standard for sauna heating appliances. If your inspector asks for a specific North American listing, call Sauna Marketplace at (844) 565-1113 before you order and we will get you HUUM documents.

I am outside the US and Canada. Where can I buy CORE?

From a HUUM dealer in your country. Enter your country in the buy box on this page and we will point you to HUUM dealers near you.

Documents and sources

HUUM CORE installation and operation manual (US) (v6, May 2026)
HUUM CORE product page
HUUM warranty terms (v4)
HUUM UKU control system manual (US) (UKU 4.2 US v1)
HUUM sauna heater calculator
HUUM CORE at Sauna Marketplace

Photos