The HUUM STEEL 11STU Package is the complete ready-to-operate bundle for the 10.5kW STEEL electric sauna heater - covering the heater, UKU Local controller, UKU Extension Box, and 330 lbs of sauna stones (10 boxes, 3-5 cm rounded olivine) in a single order. The STEEL is a distinctly different product from the CLIFF: where the CLIFF is a slim, open-cage rectangular pillar 10.6" wide and 6.3" deep, the STEEL is an enclosed square stainless steel pillar measuring 12.6" x 12.6" - a larger footprint with dramatically more stone capacity. The CLIFF 10.5kW holds 165 lbs of stones (5 boxes). The STEEL 10.5kW holds 330 lbs (10 boxes) - exactly double. The additional stone mass produces softer, more even steam and longer-lasting heat per session. The STEEL 10.5kW covers sauna rooms from 353 to 600 cubic feet - the same room range as the CLIFF 11STU Pkg - but with twice the stone reserve and at a larger heater footprint. The 10.5kW STEEL requires a 50A circuit breaker and 6AWG wire, which is a larger electrical specification than the CLIFF 10.5kW (30A/10AWG) - a key difference to confirm with your electrician before ordering. UKU Extension Box is required and included. Internal air duct increases heat-up speed by 25%. Max 230°F. SGS certified. 5-year limited warranty (excluding elements). Designed and made in Estonia by HUUM.
What the package includes - heater, controller, Extension Box, and 330 lbs of stones
The STEEL 11STU Package (SKU 534-BDL-STEEL105STULBX) combines all four items needed to operate the STEEL 10.5kW in a single order. The STEEL heater has no built-in controls and requires a UKU controller for all operation. At 10.5kW, the UKU Extension Box is also required. Purchasing the STEEL 10.5 as a heater-only unit would leave the buyer to separately source the UKU controller, the UKU Extension Box, and 10 boxes of stones before the first session could run. This package includes all four items: heater, UKU Local controller, UKU Extension Box, and 330 lbs of stones (10 boxes, 3-5 cm rounded olivine). The buyer needs only to provide the electrical installation (240V/1PH, 50A, 6AWG) and any optional STEEL accessories to complete the installation.
STEEL vs CLIFF - same room range, double the stone capacity
The STEEL 10.5kW and the CLIFF 10.5kW both cover 353-600 cubic feet at 10.5kW output. The differences between them are form factor and stone capacity. The CLIFF is a slim open-cage rectangular pillar (10.6" x 6.3") that puts the stones on open visual display through the recycled cage ribs. The STEEL is an enclosed square pillar (12.6" x 12.6") with a stainless steel outer casing that encloses the stone column inside a cavity - the stones are less visually exposed than in the CLIFF. The STEEL holds 330 lbs (10 boxes, 3-5 cm) vs the CLIFF's 165 lbs (5 boxes). HUUM's description of the consequence: the more stones there are, the softer the steam is rather than sharp steam - because each stone's temperature is lower when more stones share the heat load, producing softer, more even steam. The STEEL also carries a different electrical requirement: 50A/6AWG vs the CLIFF's 30A/10AWG at the same 10.5kW output. Safety clearances at 10.5kW for the STEEL are 4" (10 cm) at the sides - the same numeric clearance as the CLIFF 10.5kW, but achieved by a different optimized structural design.
STEEL and CLIFF - one material source, two design platforms
HUUM's description of the STEEL and CLIFF relationship is direct: these two sauna heaters are produced from the same stainless steel sheet. The fins of the CLIFF sauna heater are made from the cutouts of STEEL sauna heaters, which ensures that all material is utilized and there is no excessive waste. The recycled-cutout origin of the CLIFF's open cage ribs is the same story from the other side: the STEEL's stainless steel body produces the rectangular cutouts that become the CLIFF's signature cage structure. Both are manufactured from the same material, in the same Estonian facility, with no excess production waste between them.
10.5kW electric sauna heater package for rooms from 353 to 600 cubic feet. STEEL 11STU Pkg - complete package: STEEL 10.5kW heater, UKU Local controller, UKU Extension Box (required for 10.5kW), and 330 lbs stones (10 boxes, 3-5 cm rounded olivine). STEEL vs CLIFF: same room range and output - STEEL holds 330 lbs stones (10 boxes) vs CLIFF's 165 lbs (5 boxes) - double the stone capacity for softer, longer-lasting steam. Enclosed square stainless steel pillar - 12.6"W x 12.6"D x 38.4"H. Internal air duct - 25% faster heat-up. Safety distances: 4" (10 cm) sides. Optional Reflect S halves clearances. Max 230°F. 240V/1PH - 50A circuit breaker - 6AWG (note: larger electrical than CLIFF 10.5kW which is 30A/10AWG). Optional: Rail S safety railing; Reflect S reflector panel; Flange CS bench embedding. Pallet delivery required. SGS certified. 5-year limited warranty (excl. elements). Designed and made in Estonia by HUUM.
10.5 kW 353 to 600 cu ft Complete package - heater, UKU Local, Extension Box, and 330 lbs stones UKU Local controller included UKU Extension Box included (required for 10.5kW) 330 lbs stones included (10 boxes, 3-5 cm rounded olivine) Double the stone capacity of CLIFF 10.5kW (330 vs 165 lbs) Enclosed square stainless steel pillar - 12.6"W x 12.6"D Internal air duct - 25% faster heat-up Safety: 4" (10 cm) sides Optional Reflect S - halves side clearances Max 230°F 240V/1PH - 50A - 6AWG SGS certified 5-year limited warranty (excl. elements) Designed and made in Estonia by HUUM
Specifications
Package contents
| Heater |
HUUM STEEL 10.5kW electric sauna heater |
| Controller (included) |
UKU Local controller |
| Extension Box (included) |
UKU Extension Box - required for 10.5kW |
| Stones (included) |
330 lbs / 150 kg (10 boxes, 3-5 cm rounded olivine) |
Performance
| Power output |
10.5 kW |
| Fuel type |
Electric (240V/1PH) |
| Room volume |
353 to 600 cu ft |
| Max temperature |
230°F (110°C) |
| Stone capacity |
330 lbs / 150 kg (10 boxes, 3-5 cm) - included in package |
| Stone size |
3-5 cm rounded olivine (1-2 in) |
| Air duct benefit |
25% faster heat-up - extends element life |
| Steam type |
Soft, even steam - double stone mass vs CLIFF 10.5kW |
STEEL vs CLIFF - form and stone comparison
| STEEL form |
Enclosed square stainless steel pillar |
| CLIFF form |
Slim open recycled-cage rectangle |
| STEEL width x depth |
12.6 in x 12.6 in (320mm x 320mm) |
| CLIFF width x depth |
10.6 in x 6.3 in (270mm x 160mm) |
| STEEL stones (10.5kW) |
330 lbs - 10 boxes |
| CLIFF stones (10.5kW) |
165 lbs - 5 boxes |
| STEEL electrical (10.5kW) |
50A / 6AWG |
| CLIFF electrical (10.5kW) |
30A / 10AWG |
Safety distances
| Sides (10.5kW STEEL) |
4 in (10 cm) |
| STEEL 6kW side clearance (ref.) |
2 in (5 cm) |
| With Reflect S panel |
Side distances can be halved (optional) |
| Bench embedding minimum |
Min. 21.7 in (550mm) must protrude above bench surface |
Physical dimensions
| Width |
12.6 in (320 mm) |
| Depth |
12.6 in (320 mm) |
| Height |
38.4 in (975 mm) |
| Profile |
Enclosed square - larger footprint than CLIFF |
| Installation |
Floor-mounted |
| Delivery |
Scheduled pallet freight - appointment required |
Electrical (STEEL 10.5kW)
| Voltage / phase |
240VAC, 1-phase, 60Hz |
| Circuit breaker |
50A dedicated circuit |
| Wire size |
6AWG |
| Note vs CLIFF 10.5kW |
STEEL requires 50A/6AWG (CLIFF 10.5kW: 30A/10AWG) |
| UKU Extension Box |
Required for 10.5kW - included in this package |
| Certification |
SGS certified |
UKU Local controller (included) and optional accessories
| Controller type |
UKU Local - physical wall panel |
| Remote / app control |
Not available (UKU Local - no Wi-Fi) |
| Safety features |
Door sensor, overheating protection, child safety lock |
| Wi-Fi upgrade |
UKU Wi-Fi controller available separately |
| Safety railing |
Rail S (STEEL-specific, light wood profiles) - sold separately |
| Reflector panel |
Reflect S (STEEL-specific, halves side clearances) - sold separately |
| Bench embedding |
Flange CS (CLIFF/STEEL shared) - sold separately |
| Origin |
Designed and made in Estonia by HUUM |
| Warranty |
5-year limited warranty (excluding elements) |
What's included
HUUM STEEL 10.5kW floor-mounted electric sauna heater - enclosed square stainless steel pillar
UKU Local controller (wall panel)
UKU Extension Box (required for 10.5kW - included)
330 lbs sauna stones (10 boxes, 3-5 cm rounded olivine)
STEEL Installation and Operation Manual
UKU Installation and Operation Manual
5-year limited warranty (excluding elements)
Required (not included): Licensed electrician for wiring (240V/1PH, 50A circuit breaker, 6AWG wire). An additional box of stones is recommended. Optional accessories (sold separately - STEEL-specific): Rail S safety railing (light wood profiles); Reflect S reflector panel (halves side clearances); Flange CS bench embedding flange (min. 21.7 in / 550mm must protrude above bench). UKU Wi-Fi controller available separately as upgrade to included UKU Local.
Why the HUUM STEEL 11STU Package stands out
330 lbs of stones - double the CLIFF at the same 10.5kW output
The STEEL 10.5kW holds 330 lbs of stones (10 boxes) vs the CLIFF 10.5kW's 165 lbs (5 boxes) - exactly double, at the same output and same room range. HUUM's explanation of why more stones produce better steam: each stone's temperature is lower the more stones share the heat load, producing softer, more even steam rather than sharp steam. A ladle of water poured over 330 lbs of stones at a lower individual stone temperature produces a gentler, wider cloud of steam than the same ladle over 165 lbs of hotter stones. For bathers who prioritize soft, enveloping steam over rapid heat-up, the STEEL's larger stone mass is the decisive specification advantage over the CLIFF at equivalent output.
Complete package - heater, controller, Extension Box, and all 10 boxes of stones
The STEEL 11STU Package combines all four items needed to operate the STEEL 10.5kW into a single order. The heater has no built-in controls and requires a UKU controller. At 10.5kW, the Extension Box is mandatory. And 10 boxes of stones must be sourced before the first session. Purchasing the heater alone leaves all three as separate orders. This package includes everything: STEEL 10.5kW heater, UKU Local controller, UKU Extension Box, and all 330 lbs of stones. The only remaining requirement after delivery is the licensed electrician for the 240V/1PH, 50A, 6AWG wiring.
50A / 6AWG - the key electrical distinction from CLIFF packages
The STEEL 10.5kW requires a 50A dedicated circuit and 6AWG wire. This is a meaningfully larger electrical requirement than the CLIFF 10.5kW (30A/10AWG) and the CLIFF 9kW (30A/10AWG). For buyers comparing STEEL and CLIFF at the same 10.5kW output, this electrical difference is the most critical planning distinction: a dedicated 50A/6AWG circuit rather than a 30A/10AWG circuit. Confirm this with your licensed electrician before ordering. If the existing panel capacity is limited to 30A circuits, the CLIFF 11STU Pkg would be the more practical specification at equivalent output and room range.
4" side clearances and Reflect S halving option
The STEEL 10.5kW requires 4" (10 cm) at the sides from combustible materials - the same numeric clearance as the CLIFF 10.5kW, achieved by the STEEL's well-optimized structural design. For installations where even 4" of clearance is tight, the optional Reflect S reflector panel (sold separately, STEEL-specific) can halve the side clearances. The STEEL 6kW achieves 2" side clearances - the 10.5kW's 4" reflects the proportionally larger output at the same slim design principle. At 12.6" x 12.6", the STEEL's square footprint is larger than the CLIFF but still compact for the 330-lb stone load it carries.
Internal air duct and direct element-stone contact
The STEEL 10.5kW includes the internal air duct that HUUM fits across the STEEL platform - channeling air through the stone cavity to increase heating speed by up to 25% and reduce thermal stress on the heating elements, extending their service life. The stones are in direct contact with the heating elements for maximum heat transfer efficiency from element surface to stone mass. HUUM's description: the unit is engineered so that the sauna stones are in direct contact with the heating elements for more efficient heat transference. At 330 lbs, the STEEL's stone column benefits more from the air duct's directed airflow than the CLIFF's smaller stone load.
STEEL and CLIFF - paired platforms from one material source
The STEEL 11STU Package covers the 10.5kW configuration of the STEEL platform. The STEEL is available as: STEEL 6 (6kW, 212-353 cu ft, heater only H1006012 - 330 lbs stones sold separately, 30A/10AWG) and STEEL 10.5 in this package (10.5kW, 353-600 cu ft, complete package, 50A/6AWG). The STEEL Mini 4 (3.5kW, wall-mounted, much smaller) is a separate product. HUUM produces the CLIFF and STEEL from the same stainless steel sheet, with the CLIFF's cage fins fabricated from the cutouts of STEEL manufacturing. Both platforms share the same stone-primary philosophy, SGS certification, and 5-year warranty. Designed and made in Estonia by HUUM. We are an authorized HUUM dealer.
About HUUM
Designed in Estonia - SGS Certified - STEEL Series - Complete Package - Double Stone Capacity
HUUM STEEL 11STU Pkg. 10.5kW. 353-600 cu ft. 330 lbs stones (10 boxes). Heater, UKU Local, Extension Box.
HUUM is an Estonian sauna heater company. The STEEL 11STU Package is the complete ready-to-operate bundle for the STEEL 10.5kW electric sauna heater. Enclosed square stainless steel pillar, 330 lbs stones (10 boxes - double the CLIFF's capacity), UKU Local controller, UKU Extension Box, and internal air duct (25% faster heat-up) all included. 50A/6AWG wiring required. Pallet delivery. We are an authorized HUUM dealer.
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10.5kW electric - 353-600 cu ft - enclosed square stainless steel pillar
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330 lbs stones included (10 boxes) - double the CLIFF 10.5kW stone capacity
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UKU Local + UKU Extension Box included - all required components
- 4" side clearances - Reflect S halves distances (sold separately)
- 50A/6AWG required - SGS certified - 5-year warranty (excl. elements)
STEEL 11STU Pkg vs CLIFF 11STU Pkg vs STEEL 6 - choosing between STEEL and CLIFF
STEEL 11STU Pkg vs CLIFF 11STU Pkg vs STEEL 6 - stone capacity, form, and electrical
Three HUUM electric configurations serve the 353-600 cu ft range and the STEEL platform. STEEL 6 H1006012 (heater only): 6kW, 212-353 cu ft, 12.6"W x 12.6"D enclosed square pillar, 330 lbs stones sold separately, 2" side clearances, 30A/10AWG, no Extension Box. Right for smaller rooms where the STEEL's large stone capacity and enclosed format are priorities, with components sourced independently. CLIFF 11STU Pkg (534-BDL-CLIFF105STULBX): 10.5kW, 353-600 cu ft, slim open-cage pillar 10.6"W x 6.3"D, 165 lbs stones (5 boxes) included, 4" sides, 30A/10AWG, UKU Local + Extension Box included. Right when the CLIFF's slim open-cage Red Dot Award design, lower electrical requirement (30A vs 50A), and complete package are the priorities. STEEL 11STU Pkg 534-BDL-STEEL105STULBX (this listing): 10.5kW, 353-600 cu ft, enclosed square pillar 12.6"W x 12.6"D, 330 lbs stones (10 boxes) included, 4" sides, 50A/6AWG, UKU Local + Extension Box included. Right when maximum stone capacity (330 lbs), softer steam, and the enclosed stainless steel aesthetic are the priority over the CLIFF's slimmer cage form and lower electrical requirement.
Manuals and Documents
Warranty
5-year limited warranty (excluding elements)
The HUUM STEEL 10.5kW carries HUUM's 5-year limited warranty from the date of purchase. The warranty covers defects in manufacturing and materials under normal use and maintenance conditions. Heating elements are excluded from the 5-year term and carry a separate warranty period per the warranty document. The warranty does not cover damage caused by improper installation, failure to follow the installation and operating guidelines, use of incorrect stone type or size (decorative stones must not be used; use only rounded olivine 3-5 cm in the STEEL), operating without the required stone load, or damage from inadequate electrical installation (50A circuit breaker and 6AWG wire required). The UKU Local controller and UKU Extension Box included in the package carry their own separate HUUM product warranty terms. Proof of purchase from an authorized HUUM dealer is required for warranty claims. We are an authorized HUUM dealer.
