HUUM STEEL 9 STEEL Series 9.0kW Sauna Heater
The HUUM STEEL 9 is a 9kW floor-standing electric sauna heater for rooms from 318 to 530 cubic feet, in a slim brushed stainless steel tower. This listing is the heater only. A UKU control unit and sauna stones are required for operation and sold separately. No UKU Extension Box is required for the 9kW output level. The STEEL 9 is the mid-range model in the HUUM STEEL floor-standing series - the step up from the STEEL 6 (177-318 cu ft) for rooms from 318 to 530 cubic feet, and the step down from the STEEL 10.5 (353-706 cu ft) for rooms that don't require the 10.5kW's output or Extension Box. All three STEEL floor-standing models share the same slim rectangular stainless tower body, 330-lb stone capacity, integrated air duct, and adjustable legs. For a complete installation including control and stones in a single purchase, see the HUUM STEEL 9STU Package listing at BathingBrands.
STEEL design - slim stainless tower, 330 lbs of stone
The HUUM STEEL heater is a slim, brushed stainless steel rectangular tower that stands on the sauna floor with 4" (10 cm) clearance from the surrounding walls. Despite its relatively compact footprint, it carries 330 lbs of 2"-4" (5-10 cm) rounded olivine diabase stones - substantially more stone mass than most comparably sized wall-mounted heaters and more than many other floor-standing heaters at this output level. The slim rectangular profile fits naturally against a sauna wall or in a corner without requiring as much bench clearance as wider cylindrical or boxy heater forms. The integrated internal air duct reduces heat-up time by approximately 25% from switch-on and extends element service life by directing airflow efficiently through the 330-lb stone mass during the warm-up cycle. Adjustable legs allow fine-tuning of the heater's level position on the sauna floor. An optional embedding flange (sold separately) enables bench-embedding installation where the heater is set into the bench structure rather than standing free on the floor.
9kW mid-range STEEL - no Extension Box required
The STEEL floor-standing series has three output levels: 6kW (177-318 cu ft, 30A / 10 AWG, 2" clearance, no Extension Box), 9kW (318-530 cu ft, 50A / 8 AWG, 4" clearance, no Extension Box), and 10.5kW (353-706 cu ft, 50A / 8 AWG, 4" clearance, Extension Box required). The STEEL 9 is the mid-range model - the heavier electrical specification than the STEEL 6 (stepping from 30A / 10 AWG to 50A / 8 AWG) but without the Extension Box requirement that the STEEL 10.5 adds. For rooms from 318 to 530 cubic feet where the STEEL 6's 318 cu ft ceiling is insufficient, the STEEL 9 is the correctly matched STEEL model without the additional Extension Box hardware. A licensed electrician is required for the 50A / 8 AWG connection. Do not connect to a GFI/GFCI breaker.
330 lbs of 2"-4" stones - correct STEEL specification
The STEEL 9 requires 330 lbs (10 boxes) of 2"-4" (5-10 cm) rounded olivine diabase stones - the standard HUUM stone specification used across the DROP, HIVE, and STEEL series. This stone size is different from the 1"-2" stones required by the CLIFF series. Stones are not included in this listing and must be purchased separately. The Stone Requirements document below specifies the exact type and placement guidance. Do not use CLIFF-specification 1"-2" stones in the STEEL basket - the different basket geometry and element configuration are designed for the 2"-4" stone size.
9kW floor-standing electric sauna heater for rooms from 318 to 530 cubic feet. Slim brushed stainless steel tower. Mid-range STEEL - between the 6kW and 10.5kW models. No UKU Extension Box required. UKU control (Local Black or WiFi) sold separately. Stones: 330 lbs (10 boxes) 2"-4" rounded olivine (sold separately). Single 50A breaker, 8 AWG wire. 4" safety clearance from walls. Integrated air duct - 25% faster heat-up. Adjustable legs. Bench-embedding possible. Max 230°F. SGS Listed. 5-year warranty (elements excluded). Made in Estonia by HUUM. See STEEL 9STU Package for complete bundled purchase.
9 kW 318 to 530 cu ft Slim brushed stainless steel tower Mid-range STEEL - no Extension Box required 330 lb stone capacity 2"-4" rounded olivine (10 boxes) sold separately UKU control sold separately Single 50A breaker - 8 AWG - 240V 1-phase 4" safety clearance from walls Integrated air duct - 25% faster heat-up Adjustable legs SGS Listed - made in Estonia 5-year warranty (elements excluded)
Specifications
Electrical
| Power output |
9 kW |
| Voltage |
240V / 1-phase / 60 Hz |
| Amperage draw |
37.5 A |
| Circuit breaker required |
Single 50A (standard 2-pole - no GFI/GFCI) |
| Wire gauge |
8 AWG |
| UKU Extension Box required |
No - not required for 9kW |
| Certification |
SGS Listed |
Room sizing and stones
| Room volume |
318 to 530 cu ft |
| Stone capacity |
330 lbs (10 boxes) |
| Stones included |
No - sold separately |
| Stone size |
2" to 4" (5-10 cm) rounded olivine |
| Max temperature |
230°F (110°C) |
Physical and clearances
| Profile |
Slim rectangular stainless steel tower |
| Safety clearance from walls |
4" (10 cm) |
| Mounting |
Floor-standing with adjustable legs |
| Bench-embedding |
Possible - embedding flange sold separately |
| Air duct |
Integrated internal - 25% faster heat-up |
| Construction |
Brushed stainless steel |
| Origin |
Made in Estonia by HUUM |
Control options (sold separately)
| UKU Local Black |
Wall-mounted digital control - on-site operation |
| UKU WiFi |
HUUM app - iOS and Android - remote preheat |
| UKU Extension Box |
Not required for 9kW |
STEEL floor-standing series
| STEEL 6kW |
177-318 cu ft | 30A / 10 AWG | 2" clearance | No ext box |
| STEEL 9kW (this listing) |
318-530 cu ft | 50A / 8 AWG | 4" clearance | No ext box |
| STEEL 10.5kW |
353-706 cu ft | 50A / 8 AWG | 4" clearance | Ext box required |
| All models |
Same slim stainless tower | 330 lbs stones |
Warranty
| Warranty period |
5 years (elements excluded) |
| SKU |
H1006022 |
What's included
HUUM STEEL 9kW floor-standing sauna heater - slim brushed stainless steel tower
Adjustable legs
Installation and operation manual
Required (sold separately): UKU control unit (Local Black or WiFi); 330 lbs sauna stones - 10 boxes 2"-4" rounded olivine (see Stone Requirements document). Optional (sold separately): HUUM STEEL safety railing (recommended), embedding flange (for bench mounting), reflector panels. See also: STEEL 9STU Package for a bundled purchase. A licensed electrician is required. Do not connect to a GFI/GFCI breaker.
Why the HUUM STEEL 9 stands out
9kW mid-range - no Extension Box
The STEEL 9 covers rooms from 318 to 530 cubic feet on a single 50A / 8 AWG circuit without requiring the UKU Extension Box that the STEEL 10.5 needs. For rooms in this range where the STEEL 6's 318 cu ft ceiling is insufficient, the STEEL 9 is the simplest complete STEEL installation: control plus heater plus stones, with no additional Extension Box hardware to source and mount.
330 lbs of stone in a slim tower
Despite its slim rectangular profile and relatively modest 4" wall clearances, the STEEL 9 carries 330 lbs of 2"-4" rounded olivine stones - more stone mass than most wall-mounted heaters at this output and substantially more than compact floor-standing alternatives. The large stone load provides sustained heat and soft, long-lasting steam throughout the session, including recovery between back-to-back uses.
Integrated air duct - 25% faster heat-up
The internal air duct directs airflow efficiently through the 330-lb stone mass from the start of every heating cycle, reducing heat-up time by approximately 25% and extending element life by distributing airflow evenly during warm-up. For a 318-530 cu ft room at 9kW, the air duct advantage means a meaningfully shorter wait from switch-on to bathing temperature compared to heaters without internal ducting.
4" from walls - fits mid-size room layouts
The 4" (10 cm) wall clearance of the STEEL 9 is the same as the STEEL 10.5 - minimal for a 9kW floor-standing heater with 330 lbs of stones. Corner and wall placement options in mid-size sauna rooms from 318 to 530 cu ft are more flexible with 4" clearances than with heaters that require 6" or more, giving designers more latitude in bench and heater positioning.
Adjustable legs and bench-embedding option
The adjustable legs allow precise levelling of the STEEL 9 on uneven sauna floors - practical in cabin saunas, older buildings, or timber-framed rooms where the floor may not be perfectly level. The optional embedding flange (sold separately) enables bench-embedding installation, setting the heater body into the bench structure for a more integrated appearance and access to the stones from bench level.
STEEL 9STU Package - complete bundled option
The STEEL 9STU Package at BathingBrands bundles the STEEL 9 heater, UKU control (Local Black or WiFi at checkout), and 330 lbs of stones (10 boxes) in a single purchase. This standalone heater listing is for buyers replacing the heater only in an existing STEEL installation, or purchasing components in separate transactions. For most new installations, the Package is the more convenient path.
About HUUM
Made in Estonia - SGS Listed
HUUM STEEL 9. 9kW. 318-530 cu ft. Slim stainless tower. 330 lbs of stone. No Extension Box required.
HUUM is an Estonian sauna heater company. The STEEL 9 is the mid-range floor-standing model in the HUUM STEEL series - a slim brushed stainless steel tower carrying 330 lbs of 2"-4" rounded olivine stones for rooms from 318 to 530 cubic feet on a single 50A / 8 AWG circuit, with no UKU Extension Box required. This listing is the heater only. UKU control and 330 lbs of stones are required and sold separately. See the STEEL 9STU Package for a bundled purchase. We are an authorized HUUM dealer.
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9kW, 318-530 cu ft - single 50A / 8 AWG, 240V/1PH
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Slim stainless tower - 4" clearance, 330 lbs stone capacity
- No UKU Extension Box required
- Internal air duct, adjustable legs, bench-embedding possible
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UKU control + stones sold separately - STEEL 9STU Package also available
STEEL 9 standalone vs STEEL 9STU Package
Standalone heater vs STEEL 9STU Package - which to order
This listing is the STEEL 9 heater only - adjustable legs and IOM included. For operation, a UKU control unit (Local Black or WiFi) and 330 lbs of 2"-4" rounded olivine stones (10 boxes) are required and sold separately. The STEEL 9STU Package bundles all three in a single purchase. The standalone heater is appropriate for buyers replacing just the heater in an existing STEEL installation, or sourcing components individually. For most new installations, the STEEL 9STU Package is the more convenient option. Stone size confirmation: use only 2"-4" (5-10 cm) rounded olivine in the STEEL 9 basket. Do not use CLIFF-specification 1"-2" stones. A licensed electrician is required for the 50A / 8 AWG connection. Do not connect to a GFI/GFCI breaker. STEEL safety railing recommended. Embedding flange and reflector panels sold separately.
Manuals and Documents
Warranty
5-year limited warranty (elements excluded)
The HUUM STEEL 9 is covered by HUUM's 5-year limited warranty from the date of purchase. The warranty covers defects in manufacturing and materials under normal use conditions. Heating elements are excluded from the 5-year coverage and carry their own separate warranty period. The warranty does not cover damage caused by improper installation, use of incorrect or non-approved stone type or size, operating without the required stone load, or failure to follow HUUM's installation and operating guidelines. A licensed electrician is required for all electrical connections. Do not connect to a GFI/GFCI breaker. Proof of purchase from an authorized HUUM dealer is required. We are an authorized HUUM dealer.
