HUUM STEEL 10.5STU Pkg STEEL Series 10.5kW Sauna Heater Package
The HUUM STEEL 10.5STU Package is a complete sauna heater package for rooms from 353 to 706 cubic feet, including the STEEL 10.5kW floor-standing heater, UKU sauna control (Local Black or WiFi - selected at checkout), UKU Extension Box, and 330 lbs of rounded olivine diabase sauna stones (10 boxes). The X in the SKU designates that the UKU Extension Box is included - it is a required component for the 10.5kW output level and arrives with the package at no additional purchase. The STEEL 10.5 is the top of the STEEL floor-standing series, extending the same slim stainless steel tower body and 330-lb stone capacity of the STEEL 6 and 9 into the 353-706 cu ft room range that the STEEL 9 cannot serve.
Top of the STEEL floor-standing series - 10.5kW for 353-706 cu ft
The STEEL floor-standing series runs from 6kW to 10.5kW across three output levels: STEEL 6kW (177-318 cu ft, 30A / 10 AWG, no extension box), STEEL 9kW (318-530 cu ft, 50A / 8 AWG, no extension box), and STEEL 10.5kW (353-706 cu ft, 50A / 8 AWG, extension box included). The STEEL 10.5 and STEEL 9 share the same 50A / 8 AWG electrical specification - the difference between them is output, room range, and the extension box requirement. For rooms from 353 to 530 cu ft that fall in the overlap zone between the STEEL 9 and STEEL 10.5, well-insulated standard wood-walled rooms may be adequately served by either; rooms with cold surfaces or high-frequency use benefit from the 10.5kW's additional output headroom. For rooms from 531 to 706 cu ft, the STEEL 10.5 is the correct and only STEEL floor-standing choice.
UKU Extension Box included - required at 10.5kW
The UKU Extension Box is required for all HUUM heaters above 11kW - but for the STEEL 10.5kW specifically, HUUM includes it in this package as the complete installation kit. The extension box mounts on the wall outside the sauna room and manages the connection between the heater's higher load and the UKU control panel. At 10.5kW on a single 50A / 8 AWG circuit, the extension box is the required intermediary hardware between the heater elements and the UKU control. Including it in the package ensures all required components arrive together and no separate hardware purchase is needed. The UKU Local Black control is standard at checkout; UKU WiFi is available as an upgrade for HUUM app remote preheat and scheduling on iOS and Android.
330 lbs of stone in the slim stainless tower - same body as STEEL 6 and 9
The STEEL 10.5 carries the same 330-lb stone capacity in the same slim rectangular stainless steel tower body as the STEEL 6 and STEEL 9. All three floor-standing STEEL models share identical body dimensions, 4" (10 cm) safety clearances from walls (at 9kW and above), integrated internal air duct, and adjustable legs. The physical heater footprint and installation procedure are the same regardless of which STEEL output level is selected. The 10 boxes of 2"-4" (5-10 cm) rounded olivine diabase stones included in this package are the correct type and quantity for the STEEL 10.5.
Complete 10.5kW floor-standing sauna heater package for rooms from 353 to 706 cubic feet. Includes STEEL 10.5kW heater, UKU control (Local Black or WiFi - select at checkout), UKU Extension Box (required at 10.5kW - included), and 330 lbs of rounded olivine diabase stones (10 boxes). Top of the STEEL floor-standing series - same slim stainless tower as STEEL 6 and 9. 330 lbs stone capacity. Integrated air duct - 25% faster heat-up. 4" safety clearance from walls. Single 50A breaker, 8 AWG wire - same as STEEL 9. 240V / 1-phase. Adjustable legs. Bench-embedding possible. Max 230°F. SGS Listed. 5-year warranty (elements excluded). Made in Estonia by HUUM.
Complete package - control + ext box + 330 lbs stones 10.5 kW 353 to 706 cu ft Top of the STEEL floor-standing series Slim stainless steel tower - same body as STEEL 6 and 9 330 lb stone capacity - 10 boxes included UKU Extension Box included UKU Local Black or UKU WiFi - select at checkout HUUM app - iOS and Android (WiFi variant) Integrated air duct - 25% faster heat-up 4" safety clearance from walls Single 50A breaker - 8 AWG - 240V 1-phase SGS Listed - made in Estonia 5-year warranty (elements excluded)
Specifications
Electrical
| Power output |
10.5 kW |
| Voltage |
240V / 1-phase / 60 Hz |
| Amperage draw |
43.75 A |
| Circuit breaker required |
Single 50A (standard 2-pole - no GFI/GFCI) |
| Wire gauge |
8 AWG |
| UKU Extension Box |
Required - included in this package |
| Certification |
SGS Listed |
Room sizing and stones
| Room volume |
353 to 706 cu ft |
| Stone capacity |
330 lbs (150 kg) |
| Stones included |
Yes - 10 boxes rounded olivine diabase |
| Stone size |
2" to 4" (5-10 cm) rounded |
| 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 - select at checkout
| UKU Local Black |
Wall-mounted digital control - on-site operation |
| UKU WiFi |
Adds HUUM app remote preheat and scheduling |
| App |
HUUM app - iOS and Android (WiFi variant) |
| UKU Extension Box |
Required and included in this package |
STEEL floor-standing series
| STEEL 6kW |
177-318 cu ft | 30A / 10 AWG | 2" clearance | No ext box |
| STEEL 9kW |
318-530 cu ft | 50A / 8 AWG | 4" clearance | No ext box |
| STEEL 10.5kW (this) |
353-706 cu ft | 50A / 8 AWG | 4" clearance | Ext box included |
| All models |
Identical slim stainless tower | 330 lbs stones |
Warranty
| Warranty period |
5 years (elements excluded) |
| SKU |
534-BDL-STEEL105STULBX |
What's included
HUUM STEEL 10.5kW floor-standing sauna heater - brushed stainless steel tower
UKU sauna control (Local Black or WiFi - selected at checkout)
UKU Extension Box (required for 10.5kW - included)
Rounded olivine diabase sauna stones - 10 boxes (330 lbs)
Adjustable legs
Installation and operation manual
Optional accessories (sold separately): HUUM STEEL safety railing (recommended), STEEL embedding flange (for bench mounting), reflector panels (reduce wall clearances further). A licensed electrician is required for all electrical connections.
Why the HUUM STEEL 10.5STU Package stands out
Top of the STEEL series - 353-706 cu ft
The STEEL 10.5 is the highest output in the STEEL floor-standing range, covering rooms from 353 to 706 cubic feet in the same slim stainless tower body as the 6 and 9kW models. For rooms above 530 cu ft that require the STEEL's slim profile and minimal clearances, the 10.5kW is the correct and only STEEL floor-standing choice. All three STEEL output levels share identical body dimensions and 330-lb stone capacity.
UKU Extension Box included - complete package
The UKU Extension Box is required at the 10.5kW output level and is included in this package. No separate hardware purchase is needed. The X in the SKU suffix confirms its inclusion. The extension box mounts on the wall outside the sauna room and manages the connection between the 10.5kW load and the UKU control. Everything required for a complete installation arrives together.
Same 50A / 8 AWG as STEEL 9 - no heavier wiring
Despite the step up from 9kW to 10.5kW, the electrical specification does not change: both the STEEL 9 and STEEL 10.5 require a single 50A / 8 AWG circuit. For installations where the panel has a 50A slot available and 8 AWG wire is already planned or in place, the STEEL 10.5 provides 17% more output headroom than the STEEL 9 with no change to the wiring specification.
330 lbs of stone in the slim stainless tower
The STEEL 10.5 carries the same 330 lbs of rounded olivine diabase stones as the STEEL 6 and 9 - more output driving the same stone mass produces faster heat-up and greater capacity to sustain temperature through extended sessions in the larger room volumes the 10.5kW covers. All 10 boxes of 2"-4" rounded olivine included are correctly specified for the STEEL basket geometry.
4" from walls - fits tight large-room layouts
The STEEL 10.5 requires only 4" (10 cm) wall clearance - the same as the STEEL 9 - which is minimal for a 10.5kW floor-standing heater at this output level. For large sauna rooms where bench positions or structural constraints limit available space around the heater position, the slim STEEL tower with 4" clearances provides placement flexibility that wider heaters at equivalent output cannot match.
UKU WiFi - remote preheat for a large sauna
A 353-706 cu ft sauna room at 10.5kW takes 40-60 minutes to reach bathing temperature. Upgrading to UKU WiFi at checkout adds HUUM app control - start the preheat from anywhere and arrive to a ready sauna. The UKU Extension Box is already included; no additional hardware is needed for the WiFi upgrade on the 10.5kW STEEL.
About HUUM
Made in Estonia - SGS Listed
HUUM STEEL 10.5STU. 10.5kW. 353-706 cu ft. Top of the STEEL series. Extension box included.
HUUM is an Estonian sauna heater company. The STEEL 10.5STU Package is the complete top-of-range STEEL floor-standing installation: the 10.5kW heater with integrated air duct, UKU control (Local Black or WiFi at checkout), UKU Extension Box, and 330 lbs of rounded olivine diabase stones in 10 boxes. Same 50A / 8 AWG circuit and slim stainless tower as the STEEL 9 - with more output for larger rooms and the extension box included. A licensed electrician is required for the 50A / 8 AWG installation. We are an authorized HUUM dealer.
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Complete package - STEEL 10.5kW, UKU control, UKU Ext Box, 330 lbs stones
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10.5kW, 353-706 cu ft - single 50A / 8 AWG, 240V/1PH
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Top of the STEEL floor-standing series - same tower as 6 and 9kW
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UKU Extension Box included - complete installation in one package
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5-year warranty (elements excluded) - SGS Listed - made in Estonia
STEEL 6 vs 9 vs 10.5 - choosing the right output
Which STEEL floor-standing model is right - 6kW, 9kW, or 10.5kW?
All three floor-standing STEEL models share the same slim stainless tower, 330-lb stone capacity, integrated air duct, and adjustable legs. STEEL 6kW: 177-318 cu ft, single 30A / 10 AWG, 2" wall clearance, no extension box. STEEL 9kW: 318-530 cu ft, single 50A / 8 AWG, 4" wall clearance, no extension box. STEEL 10.5kW: 353-706 cu ft, single 50A / 8 AWG, 4" wall clearance, UKU Extension Box required and included. The 9 and 10.5 share the same electrical specification - the choice between them is room size and extension box preference. For rooms below 354 cu ft, the STEEL 9 is the correctly sized choice and does not require the extension box. For rooms from 531-706 cu ft, the STEEL 10.5 is the only option. For rooms 354-530 cu ft, standard rooms can be served by either; rooms with cold surfaces or intensive use benefit from the 10.5kW's headroom. STEEL Mini 3.5kW wall-mounted is available separately for rooms 106-177 cu ft.
Licensed electrician required. No GFI/GFCI. STEEL safety railing recommended. Embedding flange and reflector panels sold separately.
Manuals and Documents
Warranty
5-year limited warranty (elements excluded)
The HUUM STEEL 10.5STU Package 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 stones, operating the heater 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.
