The HUUM CLIFF 11 is an 11kW floor-standing electric sauna heater for rooms from 354 to 566 cubic feet, with a natural stone surface exterior. This listing is the heater only. A UKU control unit, UKU Extension Box, and sauna stones are all required for operation and sold separately. The CLIFF 11 is the highest-output model in the CLIFF floor-standing series, sharing the same natural stone exterior, slender tower profile, 165-lb stone capacity, and Red Dot Award-winning design as the CLIFF 6 and CLIFF 9 - now for the 354-566 cu ft room range on a 50A / 6 AWG circuit with an Extension Box required. For a complete installation including control, Extension Box, and stones in a single purchase, see the HUUM CLIFF 11STU Package listing at BathingBrands.
Natural stone surface - the CLIFF aesthetic at 11kW
The CLIFF heater is defined by its natural stone exterior - actual natural stone panels covering the slender tower body that give the heater the visual character of a Nordic cliff face. The Red Dot Award-winning design principle is that the heater should be a stone element in the sauna room rather than a metal appliance. This design is fully present at 11kW: the same natural stone exterior, the same slim rectangular tower profile, the same minimal footprint, and the same CLIFF aesthetic as the 6 and 9kW models. For buyers who want the CLIFF's distinctive look in a larger sauna room from 354 to 566 cubic feet, the CLIFF 11 delivers it. The UKU Extension Box is required at 11kW and is included in the CLIFF 11STU Package but must be purchased separately when ordering this standalone heater.
UKU Extension Box required - the critical difference from CLIFF 6 and 9
The CLIFF 6 (30A / 10 AWG) and CLIFF 9 (50A / 8 AWG) both operate directly from the UKU control without an Extension Box. The CLIFF 11 at 11kW requires a UKU Extension Box - this is the defining installation difference between the CLIFF 11 and the lower-output CLIFF models. The Extension Box mounts on the wall outside the sauna room and manages the connection between the 11kW heater load and the UKU control panel. When ordering the standalone heater (this listing), the Extension Box must be purchased separately alongside the UKU control and stones. The CLIFF 11STU Package includes the heater, UKU Local Black or WiFi control, Extension Box, and 165 lbs of stones in a single bundled purchase.
165 lbs of 1"-2" stones - the CLIFF-specific specification
The CLIFF 11 carries the same 165-lb stone capacity as the CLIFF 6 and CLIFF 9, in the same CLIFF-specific 1"-2" (3-5 cm) rounded olivine diabase stone size. This smaller stone size is different from the 2"-4" stones used in the DROP, HIVE, and STEEL series and must not be substituted. The removable internal basket ribs make loading and precisely placing 165 lbs of small stones into the narrow tower basket practical. The integrated internal air duct reduces heat-up time by approximately 25% by directing airflow efficiently through the stone mass from switch-on, and extends element life by improving airflow distribution during warm-up.
11kW floor-standing sauna heater for rooms from 354 to 566 cubic feet. Natural stone surface exterior - Red Dot Award-winning CLIFF design. Slender tower, minimal footprint. 165 lbs stone capacity. 1"-2" rounded olivine (CLIFF-specific stone size). Internal air duct - 25% faster heat-up. Removable ribs for precise stone loading. Required (all sold separately): UKU control (Local Black or WiFi); UKU Extension Box; 165 lbs stones (5 boxes 1"-2" rounded olivine). Single 50A breaker, 6 AWG wire. 240V / 1-phase. Max 230°F. SGS Listed. 5-year warranty (elements excluded). Made in Estonia by HUUM. See CLIFF 11STU Package for complete bundled purchase.
11 kW 354 to 566 cu ft Natural stone surface exterior - Red Dot Award design Slender floor-standing tower 165 lb stone capacity 1"-2" rounded olivine - CLIFF-specific stone size Internal air duct - 25% faster heat-up Removable ribs for stone loading UKU control sold separately UKU Extension Box required - sold separately 165 lbs stones (5 boxes) sold separately Single 50A breaker - 6 AWG - 240V 1-phase SGS Listed - made in Estonia 5-year warranty (elements excluded)
⚠️ Three components required for operation - all sold separately: (1) UKU control unit (Local Black or WiFi); (2) UKU Extension Box - required at 11kW, not needed for CLIFF 6 or 9; (3) 165 lbs sauna stones - 5 boxes of 1"-2" rounded olivine (CLIFF-specific size). See the CLIFF 11STU Package listing for a single bundled purchase including all three.
⚠️ CLIFF stone size: 1"-2" (3-5 cm) - different from DROP, HIVE, and STEEL. The CLIFF requires 1"-2" (3-5 cm) rounded olivine stones. Do not use 2"-4" stones from DROP, HIVE, or STEEL packages in the CLIFF basket - incorrect stone size restricts airflow and can damage elements.
ℹ️ CLIFF 11 vs CLIFF 9 - the Extension Box threshold. CLIFF 9 (318-530 cu ft, 50A / 8 AWG): no Extension Box required. CLIFF 11 (354-566 cu ft, 50A / 6 AWG): UKU Extension Box required. For rooms 354-530 cu ft in the overlap zone, the CLIFF 9 is adequate for standard well-insulated rooms and does not require the Extension Box. The CLIFF 11 provides more output headroom for cold surfaces or high-frequency use and requires the Extension Box. Both use 50A breakers; wire gauge differs (8 AWG for CLIFF 9, 6 AWG for CLIFF 11).
Specifications
Electrical
| Power output |
11 kW |
| Voltage |
240V / 1-phase / 60 Hz |
| Amperage draw |
45.8 A |
| Circuit breaker required |
Single 50A (standard 2-pole - no GFI/GFCI) |
| Wire gauge |
6 AWG |
| UKU Extension Box |
Required - sold separately (included in PKG) |
| Certification |
SGS Listed |
Room sizing and stones
| Room volume |
354 to 566 cu ft |
| Stone capacity |
165 lbs (5 boxes) |
| Stones included |
No - sold separately |
| Stone size |
1" to 2" (3-5 cm) rounded - CLIFF-specific |
| Max temperature |
230°F (110°C) |
Design and installation
| Exterior surface |
Natural stone - Nordic cliff face aesthetic |
| Profile |
Slender vertical tower - floor-standing |
| Air duct |
Integrated internal - 25% faster heat-up |
| Stone loading |
Removable ribs for easier precise loading |
| Design award |
Red Dot Award winner |
| Origin |
Made in Estonia by HUUM |
Required components (sold separately)
| UKU Local Black |
Wall-mounted digital control - on-site operation |
| UKU WiFi |
Adds HUUM app remote preheat and scheduling |
| UKU Extension Box |
Required at 11kW - mount outside sauna room |
| Stones |
165 lbs (5 boxes) 1"-2" rounded olivine diabase |
CLIFF floor-standing series
| CLIFF 6kW |
177-318 cu ft | 30A / 10 AWG | No ext box |
| CLIFF 9kW |
318-530 cu ft | 50A / 8 AWG | No ext box |
| CLIFF 11kW (this) |
354-566 cu ft | 50A / 6 AWG | Ext box required |
| All CLIFF models |
Natural stone surface | 165 lbs | 1"-2" olivine |
Warranty
| Warranty period |
5 years (elements excluded) |
| SKU |
H1004032 |
What's included
HUUM CLIFF 11kW floor-standing sauna heater - natural stone surface exterior
Installation and operation manual
Required (all sold separately): UKU control unit (Local Black or WiFi); UKU Extension Box (required at 11kW); 165 lbs sauna stones - 5 boxes 1"-2" rounded olivine (CLIFF-specific size). See also: CLIFF 11STU Package for a bundled purchase including all required components. A licensed electrician is required. Do not connect to a GFI/GFCI breaker.
Why the HUUM CLIFF 11 stands out
Natural stone surface at 11kW - top of the CLIFF series
The CLIFF 11 brings the natural stone exterior and Red Dot Award-winning design of the CLIFF family to rooms from 354 to 566 cubic feet - the largest room range in the floor-standing CLIFF series. The same natural stone panels, the same slender tower body, and the same minimal footprint as the CLIFF 6 and 9 - now with 11kW output and the UKU Extension Box for the larger room range.
Extension Box required - plan before ordering
The UKU Extension Box is a required component for the CLIFF 11 and must be purchased alongside the control and stones when ordering this standalone heater. It is not required for CLIFF 6 or 9. The CLIFF 11STU Package includes the Extension Box, making it the simpler single-purchase path. For buyers ordering components separately, confirm all three required items - control, Extension Box, and stones - are in the order before completing the purchase.
50A / 6 AWG - heavier wire than CLIFF 9
The CLIFF 11 shares the 50A breaker requirement with the CLIFF 9 but requires 6 AWG wire rather than the CLIFF 9's 8 AWG. For installations where an 8 AWG wire run is already planned or in place for a CLIFF 9 consideration, stepping up to the CLIFF 11 requires the heavier 6 AWG specification. Confirm wire gauge with a licensed electrician before ordering.
165 lbs of 1"-2" stone - same as CLIFF 6 and 9
All three CLIFF floor-standing models carry the same 165-lb stone load in the same CLIFF-specific 1"-2" (3-5 cm) rounded olivine size. At 11kW, more output driving the same stone mass produces faster heat-up in the larger 354-566 cu ft room range. The removable basket ribs and integrated air duct are the same across all three CLIFF output levels.
354-566 cu ft - the top CLIFF floor-standing range
The CLIFF 11 is the appropriate choice for rooms from 354 to 566 cubic feet where the CLIFF 9's 530 cu ft ceiling is insufficient, or where the room has cold surfaces - glass walls, tile floors, masonry cladding - that push the adjusted cubic footage above what the 9kW can manage effectively. For standard well-insulated rooms in the 354-530 cu ft overlap with the CLIFF 9, either model can serve the room; the CLIFF 11 provides output headroom.
CLIFF 11STU Package - the complete purchase path
The CLIFF 11STU Package at BathingBrands bundles the CLIFF 11 heater, UKU control (Local Black or WiFi at checkout), UKU Extension Box, and 165 lbs of 1"-2" rounded olivine stones in a single purchase. For buyers who want all required components together without sourcing them separately, the Package is the more straightforward option. This standalone listing is for buyers replacing a heater in an existing installation or purchasing components individually.
About HUUM
Made in Estonia - Red Dot Award winner
HUUM CLIFF 11. 11kW. 354-566 cu ft. Natural stone surface. Top of the CLIFF floor-standing series.
HUUM is an Estonian sauna heater company. The CLIFF 11 is the top-output model in the CLIFF floor-standing series - the same Red Dot Award-winning natural stone exterior, slender tower profile, 165-lb stone capacity, 1"-2" stone specification, removable basket ribs, and integrated air duct as the CLIFF 6 and 9, now at 11kW for rooms from 354 to 566 cubic feet with the UKU Extension Box required. This listing is the heater only. UKU control, UKU Extension Box, and 165 lbs of 1"-2" stones are required and sold separately. See the CLIFF 11STU Package for a complete bundled purchase. We are an authorized HUUM dealer.
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11kW, 354-566 cu ft - single 50A / 6 AWG, 240V/1PH
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Natural stone surface - Red Dot Award, same tower as CLIFF 6 and 9
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UKU Extension Box required - not needed for CLIFF 6 or 9
- 165 lbs 1"-2" stones, removable ribs, internal air duct
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CLIFF 11STU Package available - includes control, ext box, and stones
CLIFF 11 standalone vs CLIFF 11STU Package
Standalone heater vs CLIFF 11STU Package - which to order
This listing is the CLIFF 11 heater only. For the CLIFF 11 to operate, three additional components are required: a UKU control unit (Local Black or WiFi), a UKU Extension Box, and 165 lbs of 1"-2" rounded olivine stones in 5 boxes. All three are sold separately at BathingBrands. The CLIFF 11STU Package listing bundles all four components (heater, control, Extension Box, and stones) in a single purchase with one checkout. The standalone heater listing is appropriate for buyers replacing a heater only in an existing CLIFF 11 installation, or for buyers who already have some components and need only the heater. For most new installations, the CLIFF 11STU Package is the more convenient and complete purchase path. Stone size confirmation: only 1"-2" (3-5 cm) rounded olivine diabase stones must be used in the CLIFF 11 basket - do not use 2"-4" stones from DROP, HIVE, or STEEL packages. A licensed electrician is required. Do not connect to a GFI/GFCI breaker.
Manuals and Documents
Warranty
5-year limited warranty (elements excluded)
The HUUM CLIFF 11 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 stone type or size (2"-4" stones must not be used - 1"-2" stones required), operating without the required stone load, operating without the required UKU Extension Box, or failure to follow HUUM's installation and operating guidelines. A licensed electrician is required. Do not connect to a GFI/GFCI breaker. Proof of purchase from an authorized HUUM dealer is required. We are an authorized HUUM dealer.
