HUUM HIVE Flow Mini LS Wood-Burning Sauna Stove w/ Firebox Extension, 8.5kW
The HUUM HIVE Flow Mini LS is an 8.5kW wood-burning sauna stove for rooms from 212 to 494 cubic feet - the compact, exterior-loading configuration of the HIVE Flow Mini platform. LS identifies the through-wall firebox extension: the stove body and 231-lb stone cage sit inside the sauna, the firebox extends through the sauna wall, and the glass door faces the adjacent room or exterior. Wood is loaded and the fire is tended from outside the sauna at all times. Bathers inside enjoy 8.5kW of heat and soft, long-lasting steam entirely undisturbed. The HIVE Flow Mini LS is the most compact exterior-feed configuration in the HUUM HIVE Flow lineup - 17.7" wide, 26.5" deep (including the LS wall extension), and 130 lbs. The same patent-pending Flow furnace that powers the standard HIVE Flow Mini delivers 75% heat retention, CO emissions of just 346 mg/m3 (versus over 1,000 mg/m3 in comparable stoves), particulate matter of 25 mg/m3 (the lowest in its category), and safety distances of just 5.9" (150mm) at the sides from combustible materials. Steam lasts over 30 minutes after the fire dies. BImSchV and CPR certified. 5-year limited warranty (excluding elements). Designed, engineered, and made in Estonia by HUUM.
LS firebox extension - compact exterior loading for small saunas
The HIVE Flow Mini LS is HUUM's most compact exterior-feed wood-burning stove. At 17.7" wide - the same body width as the standard HIVE Flow Mini - it is narrower than the HIVE Flow LS (20.7") and brings through-wall firebox loading to sauna installations where a smaller stove footprint and a smaller room range (212-494 cu ft) are the specification. The firebox extension passes through the sauna wall so wood is added and the fire is managed entirely from outside. The glass door faces the adjacent room, providing the person tending the fire a view of the flames while the sauna bathers inside are completely undisturbed. HUUM's description of the LS experience applies directly here: the extended firebox allows you to heat the sauna from an adjacent room. The large glass furnace door enhances the cozy ambiance of the adjacent space, letting you enjoy the mesmerizing flames while the sauna warms.
75% heat retention, CO 346 mg/m3, 5.9" side clearances
The HIVE Flow Mini LS shares the same patent-pending furnace design as the standard HIVE Flow Mini and the HIVE Flow LS - the three headline performance figures are identical across all Flow platform configurations. 75% of the heat from firewood stays in the sauna rather than escaping through the chimney - equivalent to four sessions from the wood that typically gives three. CO emissions of 346 mg/m3 compare to over 1,000 mg/m3 in comparable stoves. Particulate matter output of 25 mg/m3 is the lowest in its output category. Safety distances from combustible materials are just 5.9" (150mm) at the sides, achieved by the Flow furnace design without requiring any protective sheath. BImSchV (German clean combustion) and CPR certification confirm all emission and performance values are independently verified.
231 lbs of stones - over 30 minutes of steam after the fire
The HIVE Flow Mini LS holds 231 lbs (105 kg) of sauna stones in its primary stone cavity - the same capacity as the standard HIVE Flow Mini. The large stone mass accumulates heat thoroughly during the fire and sustains heat and steam well after the fire dies: HUUM describes the steam as lasting over 30 minutes after the fire goes out. For a sauna where the fire is loaded from outside via the LS extension and then allowed to burn through naturally, the stone thermal mass is what sustains the session without requiring attention from inside. Max firewood length is 11.8" (300mm). Rounded sauna stones 5-10 cm in diameter are recommended by HUUM for milder steam and better air circulation through the stone bed. 5mm top panels and 3mm sides in stainless steel.
8.5kW wood-burning sauna stove with firebox extension for rooms from 212 to 494 cubic feet. HIVE Flow Mini LS - HUUM's most compact exterior-feed Flow stove. Firebox extends through sauna wall. Wood loaded from adjacent room or outdoors. Glass door faces adjacent room. Bathers inside sauna undisturbed. Patent-pending Flow furnace: 75% heat retention - 4 sessions from 3 loads of wood. CO: 346 mg/m3 (vs 1,000+ in comparable stoves). PM: 25 mg/m3 - lowest in category. Safety distances: 5.9" sides (150mm) from combustible materials. No protective sheath required. 231 lbs stones required (7 boxes, sold separately). Steam lasts over 30 min after fire is out. 5mm top / 3mm sides stainless steel. Large glass door. Top or back flue - 115mm. Max firewood 11.8" (300mm). 6" adapter required for North America (sold separately). Dimensions: 17.7"W x 26.5"D x 34.8"H. 130 lbs. BImSchV certified - CPR certified. Pallet delivery required. 5-year limited warranty (excl. elements). Designed and made in Estonia by HUUM.
8.5 kW 212 to 494 cu ft HIVE Flow Mini LS - most compact exterior-feed Flow stove LS firebox extension through sauna wall Wood loaded from adjacent room or outdoors Glass door faces adjacent room 75% heat retention - 4 sessions per 3 wood loads CO: 346 mg/m3 - PM: 25 mg/m3 - lowest in category Safety: 5.9" sides - no protective sheath required 231 lbs stones required (7 boxes) Steam lasts over 30 min after fire out 5mm top / 3mm sides stainless steel Large glass door faces adjacent room Top or back flue - 115mm - 6" adapter required Max firewood 11.8" (300mm) 17.7"W x 26.5"D x 34.8"H - 130 lbs BImSchV certified - CPR certified Pallet delivery required 5-year limited warranty (excl. elements) Designed and made in Estonia by HUUM
Specifications
Performance
| Power output |
8.5 kW |
| Fuel type |
Wood - no electricity required |
| Room volume |
212 to 494 cu ft (6-14 m3) |
| Stone capacity |
231 lbs / 105 kg (7 boxes) - sold separately |
| Max firewood length |
11.8 in (300 mm) |
| Steam after fire out |
Over 30 minutes |
| Firebox configuration |
LS - extends through sauna wall - exterior loading |
LS firebox extension
| Firebox access |
From outside the sauna room via wall extension |
| Glass door faces |
Adjacent room or exterior |
| Wall requirement |
Non-combustible wall required for bushing |
| Dual-room effect |
Sauna heat inside + fire view and warmth outside |
| Additional depth vs standard Mini |
+5.4 in (137 mm) due to LS extension |
Flow furnace efficiency and emissions
| Heat retention in sauna |
75% of firewood heat stays in sauna |
| Sessions per wood load |
4 sessions vs 3 for conventional stoves |
| CO emissions |
346 mg/m3 (vs 1,000+ mg/m3 in comparable stoves) |
| Particulate matter |
25 mg/m3 - lowest in its category |
| Certifications |
BImSchV (German clean combustion) | CPR certified |
Physical dimensions
| Width |
17.7 in (450 mm) |
| Depth (with LS extension) |
26.5 in (674 mm) |
| Height |
34.8 in (884 mm) |
| Weight |
130 lbs |
| Standard Mini depth (no LS) |
21.1 in (537 mm) |
| Additional depth vs standard Mini |
+5.4 in (137 mm) due to LS extension |
Safety distances (combustible materials)
| Sides (A) |
5.9 in (150 mm) |
| Front (B) |
19.7 in (500 mm) |
| Back (C) |
29.5 in (750 mm) |
| Protective sheath required |
No |
Construction
| Top panels |
5 mm thick stainless steel |
| Sides |
3 mm thick stainless steel |
| Glass door |
Large - faces adjacent room in LS configuration |
| Ash management |
Ash drawer included |
| Cleaning access |
2 cleaning hatches included |
| Installation |
Floor-mounted, LS bushing through non-combustible wall |
Flue, certifications, and optional accessories
| Flue connection diameter |
115mm (4.5") |
| Flue connection position |
Top or back - selected during installation |
| North American adapter |
6" (155mm) adapter required - sold separately |
| Origin |
Designed, engineered, and made in Estonia by HUUM |
| Warranty |
5-year limited warranty (excluding elements) |
| Chimney kits |
HUUM Thru-Ceiling / Thru-Wall / Barrel Chimney Kit |
| Floor protection |
HUUM Protective Plate | HUUM Protective Bed LS |
| Safety cage |
HUUM Cage HSTV |
| Delivery |
Scheduled pallet freight - appointment required |
What's included
HUUM HIVE Flow Mini LS 8.5kW wood-burning sauna stove with LS firebox extension
Metal grate
Heat resistant glove
Splints
Metal fixing plates (x2)
Ash grate
Cleaning hatches (x2)
Ash drawer
Installation and operation manual
5-year limited warranty (excluding elements)
Required (not included): 231 lbs sauna stones (7 boxes, rounded 5-10 cm diameter recommended); 6" North American flue adapter; chimney connection. Optional accessories (sold separately): HUUM Cage HSTV; HUUM Thru-Ceiling, Thru-Wall, or Barrel Chimney Kit; HUUM Protective Plate or Protective Bed LS. A licensed chimney professional is recommended for all flue installations. Non-combustible wall required for LS firebox bushing passage.
Why the HUUM HIVE Flow Mini LS stands out
Most compact exterior-feed Flow stove - 17.7" wide
At 17.7" (450mm) wide, the HIVE Flow Mini LS is the most compact exterior-feed stove in the HUUM HIVE Flow lineup. The HIVE Flow LS - the larger 9.8kW exterior-feed configuration - is 20.7" wide. The HIVE Flow Mini LS brings the through-wall firebox loading to installations where a narrower stove body is required: smaller sauna rooms, tighter wall openings, or layouts where the 3-inch width difference between the Mini LS and the full LS matters. For a small cabin sauna in the 212-494 cu ft range where both exterior loading and a compact installation footprint are priorities, the HIVE Flow Mini LS is the purpose-built configuration.
LS exterior loading - session undisturbed throughout
Wood loaded from outside the sauna room means the firebox can be tended without opening the sauna door at any point in the session. No heat loss, no draft, no intrusion. The sauna door stays closed from the moment the session starts to the moment it ends. The glass door faces the adjacent room, giving the person managing the fire a view of the flames and the ambient warmth of the firebox radiant heat. HUUM describes this directly: the extended firebox allows you to heat the sauna from an adjacent room. For a cabin sauna with an adjoining changing room, porch, or outdoor area where fire tending from outside is operationally preferred, the HIVE Flow Mini LS is the exact configuration.
75% heat retention - 4 sessions from 3 loads of wood
The patent-pending Flow furnace keeps 75% of the heat generated from burning wood inside the sauna. HUUM's statement of the practical consequence: you can enjoy four sessions with the same amount of wood that would typically provide three sauna sessions. For a sauna fired from outside via the LS extension - where the fire is loaded and left to burn without intervention - the Flow furnace's efficiency means less wood is needed per session, less ash is produced per unit of heat delivered, and the full session runs longer from a given wood load. The same complete combustion that drives the 75% heat retention also produces CO at 346 mg/m3 and particulates at 25 mg/m3.
231 lbs of stones - steam over 30 minutes after the fire
The HIVE Flow Mini LS holds 231 lbs (105 kg) of sauna stones. The large stone mass accumulates heat from the fire and holds it well after the fire goes out. HUUM's description: the large stone volume allows full sauna bathing even over 30 minutes after the fire has died. For a sauna where the fire is managed externally via the LS extension and burns through naturally without reloading, the stone thermal reservoir is what carries the session. Rounded 5-10 cm diameter stones are recommended by HUUM for milder steam. The two cleaning hatches provide easy interior access for maintenance without disassembling the stove.
5.9" side clearances - compact installation, no sheath needed
The HIVE Flow Mini LS requires just 5.9" (150mm) at the sides from combustible materials - the same compact clearances as every Flow Series configuration. No protective sheath is required to achieve these distances; they are a result of the Flow furnace design itself, which HUUM explains produces more even heating across the stove body rather than localised hot spots. Front clearance is 19.7" (500mm) and back clearance is 29.5" (750mm). For a small sauna room in the 212-494 cu ft range where bench placement relative to the stove is important, 5.9" side clearances give meaningfully more layout flexibility than the 7.5" or larger clearances required by conventional stoves in this class.
HIVE Flow Series - Mini LS and all four configurations
The H1018012 is the 8.5kW LS (exterior-feed) configuration of the HIVE Flow Mini platform. The complete HIVE Flow Series spans four configurations: HIVE Flow Mini H1017012 (8.5kW, 212-494 cu ft, interior firebox, 21.1"D, same Flow furnace); HIVE Flow Mini LS H1018012 (this listing, 8.5kW, 212-494 cu ft, LS firebox extension, 26.5"D, 130 lbs); HIVE Flow H1015012 (9.8kW, 282-635 cu ft, interior firebox, 26.4"D, 148 lbs); HIVE Flow LS H1016012 (9.8kW, 282-635 cu ft, LS firebox extension, 29.5"D, 161 lbs). All four share the patent-pending Flow furnace, 75% heat retention, CO 346 mg/m3, PM 25 mg/m3, 150mm side clearances, BImSchV and CPR certifications, and 5-year limited warranty. Designed and made in Estonia by HUUM. We are an authorized HUUM dealer.
About HUUM
Designed in Estonia - BImSchV Certified - HIVE Flow Series - Compact LS
HUUM HIVE Flow Mini LS. 8.5kW. 212-494 cu ft. Exterior loading. 75% heat retention. 5.9" clearances.
HUUM is an Estonian sauna heater company. The HIVE Flow Mini LS is the compact exterior-feed configuration of the 8.5kW HIVE Flow Mini platform - LS firebox extends through the sauna wall, wood loaded from outside, glass door faces adjacent room, bathers inside undisturbed. Patent-pending Flow furnace: 75% heat retention, CO 346 mg/m3, PM 25 mg/m3, 5.9" side clearances without a sheath. 231 lbs stones (7 boxes) and chimney required and sold separately. Pallet delivery. We are an authorized HUUM dealer.
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8.5kW wood-burning - 212-494 cu ft - LS firebox extension through sauna wall
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75% heat retention - CO 346 mg/m3 - PM 25 mg/m3 - BImSchV certified
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231 lbs stones required (7 boxes) - steam lasts over 30 min after fire
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5.9" side clearances - 17.7"W - most compact exterior-feed Flow stove
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5-year warranty (excl. elements) - 130 lbs - pallet delivery - made in Estonia
HIVE Flow Mini LS vs HIVE Flow Mini vs HIVE Flow LS - choosing the right Flow config
HIVE Flow Mini LS vs HIVE Flow Mini vs HIVE Flow LS - exterior vs interior, small vs large room
Four HIVE Flow configurations serve two room sizes and two firebox directions. HIVE Flow Mini H1017012: 8.5kW, 212-494 cu ft, interior firebox, 21.1"D depth, glass door faces into sauna. Right when interior loading is acceptable for the 212-494 cu ft range. HIVE Flow Mini LS H1018012 (this listing): 8.5kW, 212-494 cu ft, LS firebox extension, 26.5"D, 130 lbs, glass door faces adjacent room. Right when exterior loading is the priority for the 212-494 cu ft range and the compact 17.7"-wide footprint is needed. HIVE Flow H1015012: 9.8kW, 282-635 cu ft, interior firebox, 26.4"D, 148 lbs. Right when the room is larger (up to 635 cu ft) and interior loading is acceptable. HIVE Flow LS H1016012: 9.8kW, 282-635 cu ft, LS firebox extension, 20.7"W body, 29.5"D, 161 lbs. Right when the larger room range and exterior loading are both required. The HIVE Flow Mini LS is the smallest and lightest exterior-feed option in the HIVE Flow Series. All four share the patent-pending Flow furnace, 75% heat retention, CO 346 mg/m3, PM 25 mg/m3, 5.9" side clearances, BImSchV and CPR certifications, and 5-year limited warranty.
Manuals and Documents
Warranty
5-year limited warranty (excluding elements)
The HUUM HIVE Flow Mini LS 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 unsuitable sauna stones (decorative stones must not be used as they can break under heat), operating without the required stone load, damage from inadequate chimney maintenance, or improper wall penetration preparation for the LS firebox bushing (non-combustible wall required). A licensed chimney professional is recommended for all flue installation and regular chimney sweep maintenance. Proof of purchase from an authorized HUUM dealer is required for warranty claims. We are an authorized HUUM dealer.
