The HUUM HIVE Flow is a 9.8kW wood-burning sauna stove for rooms from 282 to 635 cubic feet with a patent-pending furnace design that retains 75% of the heat from firewood inside the sauna - significantly more than conventional sauna stoves. The standard HIVE Flow has an interior firebox: the glass door faces into the sauna room, wood is loaded and the fire is managed from inside, and the bather and the fire share the same space throughout the session. This is the right configuration for installations where interior loading is preferred and the focus is on the HIVE Flow's exceptional efficiency and emissions performance rather than exterior loading convenience. CO emissions are just 346 mg/m3 versus over 1,000 mg/m3 in comparable stoves. Particulate matter output is 25 mg/m3 - the lowest in its output category. Safety distances from combustible materials are just 150mm (5.9") at the sides and back, achieved by the Flow furnace design without any protective sheath. The stove holds 330 lbs (150 kg) of stones (10 boxes, sold separately), with an optional stone cage adding a further 77-88 lbs. Steam lasts over 30 minutes after the fire dies. Top or back 115mm flue connection. Max firewood 11.8" (300mm). BImSchV and CPR certified. 5-year limited warranty (excluding elements). Designed, engineered, and made in Estonia by HUUM.
Interior firebox - fire and bather in the same room
The standard HIVE Flow keeps the firebox door facing into the sauna room. Wood is loaded by opening the large glass furnace door from inside the sauna, adding wood, and closing it again. The fire is tended from inside the session space. The large glass furnace door enhances the cozy ambiance of the sauna, letting bathers enjoy the mesmerizing flames throughout the session from the bench. For buyers who prefer the traditional Finnish sauna arrangement - where the bather tends the fire, manages the heat, and is fully present with the stove throughout the session - the standard HIVE Flow provides all of the Flow platform's efficiency and emissions advantages in the classic interior-access configuration. For buyers who want to load from an adjacent room, the HIVE Flow LS is the same stove with the firebox extension.
Patent-pending Flow furnace - 75% heat retention, 4 sessions per 3 wood loads
The HIVE Flow's patent-pending furnace creates a unique airflow pattern that keeps 75% of the heat generated from burning wood inside the sauna rather than letting it escape through the chimney. HUUM's own summary of the practical consequence: you can enjoy four sessions with the same amount of wood that would typically provide three sauna sessions. This 33% improvement in sessions per wood load is the result of more complete, efficient combustion - and the same combustion efficiency that produces the 75% heat retention also produces dramatically lower emissions: CO at 346 mg/m3 against over 1,000 mg/m3 in comparable stoves, and particulate matter at 25 mg/m3 - the lowest measured in its output category. BImSchV (German clean combustion) and CPR certifications confirm these are independently verified values.
330 lbs of stones, 5.9" side clearances, and over 30 minutes of steam
The HIVE Flow holds 330 lbs (150 kg) of sauna stones in its primary stone compartment. The optional HUUM stone cage adds capacity for a further 77-88 lbs of stones around the chimney pipe above the stove. HUUM's description of the steam performance is direct: the large stone volume allows full sauna bathing even over 30 minutes after the fire has died. For a home sauna where the session naturally extends past the fire's peak, the stone thermal mass sustains quality heat and steam without relighting or adding wood. Safety distances from combustible materials are just 150mm (5.9") at the sides and back - the same compact clearances as the HIVE Flow LS - no protective sheath required. Rounded sauna stones 5-10 cm in diameter are recommended by HUUM for milder steam.
9.8kW wood-burning sauna stove for rooms from 282 to 635 cubic feet. HIVE Flow - standard interior firebox, glass door faces into sauna room. 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: 150mm (5.9") sides and back - 500mm (19.7") front from combustible materials. No protective sheath required. 330 lbs stones required (10 boxes, sold separately). Up to 408 lbs with optional stone cage. 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: 20.7"W x 26.4"D x 34.8"H. 148 lbs. BImSchV certified - CPR certified. Pallet delivery required. 5-year limited warranty (excl. elements). Designed and made in Estonia by HUUM.
9.8 kW 282 to 635 cu ft HIVE Flow - interior firebox - glass door faces into sauna Patent-pending Flow furnace - 75% heat retention 4 sessions per 3 wood loads CO: 346 mg/m3 - PM: 25 mg/m3 - lowest in category Safety: 150mm sides and back - no protective sheath 330 lbs stones required (10 boxes) Up to 408 lbs with optional stone cage Steam lasts over 30 min after fire out 5mm top / 3mm sides stainless steel Large glass door - fire view inside sauna Top or back flue - 115mm - 6" adapter required Max firewood 11.8" (300mm) 20.7"W x 26.4"D x 34.8"H - 148 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 |
9.8 kW |
| Fuel type |
Wood - no electricity required |
| Room volume |
282 to 635 cu ft (8-18 m3) |
| Stone capacity (primary) |
330 lbs / 150 kg (10 boxes) - sold separately |
| Stone capacity with cage |
Up to 408 lbs / 185 kg (optional stone cage) |
| Max firewood length |
11.8 in (300 mm) |
| Steam after fire out |
Over 30 minutes |
| Firebox configuration |
Interior - glass door faces into sauna room |
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 |
| Furnace design |
Patent-pending - unique airflow pattern |
| Certifications |
BImSchV (German clean combustion) | CPR certified |
Safety distances (combustible materials)
| Sides and back |
5.9 in (150 mm) |
| Front |
19.7 in (500 mm) |
| Vs conventional stoves |
Conventional: 200-500 mm | HIVE Flow: 150 mm sides/back |
| Protective sheath required |
No |
Physical dimensions
| Width |
20.7 in (530 mm) |
| Depth (standard - no LS extension) |
26.4 in (670 mm) |
| Height |
34.8 in (884 mm) |
| Weight |
148 lbs (67 kg) |
HIVE Flow vs HIVE Flow LS - dimension comparison
| Firebox direction |
Flow: faces into sauna | Flow LS: faces adjacent room |
| Width (both) |
20.7 in (530 mm) - identical |
| Depth - HIVE Flow (standard) |
26.4 in (670 mm) |
| Depth - HIVE Flow LS |
29.5 in (750 mm) - deeper due to LS wall extension |
| Weight - HIVE Flow |
148 lbs (67 kg) |
| Weight - HIVE Flow LS |
161 lbs (73 kg) |
| Output, stones, furnace, certs |
Identical across both configurations |
Construction
| Top panels |
5 mm thick stainless steel |
| Sides |
3 mm thick stainless steel |
| Glass door |
Large - faces into sauna room |
| Ash management |
Ash drawer included |
| Cleaning access |
2 cleaning hatches included |
| Installation |
Floor-mounted, vertical orientation |
| Use environment |
Interior sauna - wet area |
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) |
| Optional stone cage |
HUUM stone cage - adds 77-88 lbs stone capacity |
| Optional safety cage |
HUUM Cage HSTV |
| Chimney kits |
HUUM Thru-Ceiling / Thru-Wall / Barrel Chimney Kit |
| Floor protection |
HUUM Protective Plate | HUUM Protective Bed |
What's included
HUUM HIVE Flow 9.8kW wood-burning sauna stove
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): 330 lbs sauna stones (10 boxes, rounded 5-10 cm diameter recommended); 6" North American flue adapter; chimney connection. Optional accessories (sold separately): HUUM stone cage (adds 77-88 lbs additional stone capacity); HUUM Cage HSTV; HUUM Thru-Ceiling, Thru-Wall, or Barrel Chimney Kit; HUUM Protective Plate or Protective Bed. A licensed chimney professional is recommended for all flue installations.
Why the HUUM HIVE Flow stands out
Patent-pending Flow furnace - 75% heat retention
The HIVE Flow's patent-pending furnace creates a unique airflow pattern that keeps 75% of the heat generated from burning wood inside the sauna. HUUM's precise statement: you can enjoy four sessions with the same amount of wood that would typically provide three sauna sessions. This 33% improvement in sessions per unit of firewood is not a marginal gain - it is the direct result of more complete and efficient combustion inside the Flow furnace. The same efficiency that drives the 75% heat retention also produces dramatically lower emissions, tighter safety clearances, and the long-lasting steam that continues over 30 minutes after the fire dies.
CO at 346 mg/m3 - independently verified, lowest in category
The HIVE Flow's 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. Both values are independently verified under BImSchV (the German clean combustion standard) and CPR (European Commission) certification - not manufacturer self-declarations. HUUM states that the HIVE Flow surpasses all known efficiency and environmental metrics for wood-burning stoves of its class. For buyers requiring certified emission compliance for installation approval, or for those who want documented evidence of environmental performance, these certifications are the record.
330 lbs of stones - over 30 minutes of steam after the fire
At 330 lbs (150 kg), the HIVE Flow primary stone capacity is among the largest for a stove of this output class. The stone mass accumulates heat throughout the fire's burn and holds it long after the fire dies. HUUM's description of the result: full sauna bathing even over 30 minutes after the fire has died. The optional HUUM stone cage extends capacity by a further 77-88 lbs for sessions requiring the maximum thermal reserve. Rounded sauna stones 5-10 cm in diameter are recommended by HUUM - they create less dust and allow better air circulation through the stone mass than angular stones.
5.9" side and back clearances - snug installation without sheath
The HIVE Flow requires just 150mm (5.9") at the sides and back from combustible materials - achieved by the Flow furnace design, not by a protective sheath. The front clearance is 500mm (19.7"). HUUM explains the mechanism directly: the heater warms up more evenly, allowing for snug installation. For a sauna room in the 282-635 cu ft range where bench placement close to the stove is important, 5.9" side and back clearances give meaningfully more layout flexibility than conventional stoves requiring 200-500mm. No additional accessories are required to achieve these clearances - the stove as delivered meets the 150mm specification.
Large glass door - fire view from the bench
In the standard HIVE Flow interior configuration, the large glass furnace door faces into the sauna room. The fire is visible from the benches throughout the session - the warm, moving light of the fire adds the ambient character of a live wood fire to the sauna environment. For bathers who tend their own fire and prefer to be present with the stove and the fire throughout the session, the interior glass door is central to the experience. HUUM describes this directly: the large glass furnace door enhances the cozy ambiance of your sauna, letting you enjoy the mesmerizing flames. The two cleaning hatches provide easy maintenance access without disassembling the stove.
HIVE Flow Series - Flow, Flow LS, Flow Mini, and Flow Mini LS
The H1015012 is the 9.8kW standard interior-firebox configuration of the HIVE Flow. The same 9.8kW Flow furnace is also available as the HIVE Flow LS (H1016012, same 9.8kW and 330-lb stone capacity, firebox through-wall extension, glass door faces adjacent room, 29.5"D depth, 161 lbs). The HIVE Flow Mini (H1015012 variant) and HIVE Flow Mini LS (H1017012) cover the smaller 212-494 cu ft range at 8.5kW with 231 lbs of stones. All four configurations share the same patent-pending Flow furnace, BImSchV and CPR certifications, and 5-year limited warranty. Choose the HIVE Flow (this listing) for 282-635 cu ft with interior loading. Choose the HIVE Flow LS when exterior loading is the priority. Designed and made in Estonia by HUUM. We are an authorized HUUM dealer.
About HUUM
Designed in Estonia - BImSchV Certified - HIVE Flow Series - Interior Firebox
HUUM HIVE Flow. 9.8kW. 282-635 cu ft. 75% heat retention. CO 346 mg/m3. Interior firebox.
HUUM is an Estonian sauna heater company. The HIVE Flow is a 9.8kW wood-burning stove with a patent-pending furnace that retains 75% of firewood heat inside the sauna, produces CO of 346 mg/m3 (vs 1,000+ in comparable stoves), achieves 5.9" safety distances from combustible materials without a sheath, and delivers steam for over 30 minutes after the fire dies. Standard interior firebox - glass door faces into the sauna. BImSchV and CPR certified. 330 lbs stones (10 boxes) and chimney connection required and sold separately. Pallet delivery. We are an authorized HUUM dealer.
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9.8kW wood-burning - 282-635 cu ft - interior firebox - glass door faces into sauna
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75% heat retention - CO 346 mg/m3 - PM 25 mg/m3 - BImSchV certified
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330 lbs stones required (10 boxes) - steam lasts over 30 min after fire
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5.9" side and back clearances - no protective sheath required
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5-year warranty (excl. elements) - 148 lbs - pallet delivery - made in Estonia
HIVE Flow vs HIVE Flow LS vs HIVE Flow Mini - Flow platform selection guide
HIVE Flow vs HIVE Flow LS vs HIVE Flow Mini - choosing the right HIVE Flow configuration
Four configurations carry the HIVE Flow platform across two room sizes and two firebox directions. HIVE Flow Mini H1015012 variant: 8.5kW, 212-494 cu ft, 231 lbs stones (7 boxes), interior firebox. HIVE Flow Mini LS H1017012: 8.5kW, 212-494 cu ft, 231 lbs stones (7 boxes), LS firebox extension. Both Mini variants cover smaller rooms at lower output and stone capacity. HIVE Flow H1015012 (this listing): 9.8kW, 282-635 cu ft, 330 lbs stones (10 boxes), interior firebox, 26.4"D depth, 148 lbs. Right for the 282-635 cu ft range where interior loading is preferred and the full Flow efficiency and stone capacity are needed. HIVE Flow LS H1016012: 9.8kW, 282-635 cu ft, 330 lbs stones (10 boxes), LS firebox extension through sauna wall, glass door faces adjacent room, 29.5"D depth, 161 lbs. Right when the same 9.8kW Flow output and 330-lb stone capacity are needed alongside exterior loading and a fireplace view in an adjacent room. All four share the patent-pending Flow furnace (75% heat retention, CO 346 mg/m3, PM 25 mg/m3, 150mm side and back clearances), BImSchV and CPR certifications, and 5-year limited warranty. Choose the HIVE Flow for the 282-635 cu ft range with interior loading.
Manuals and Documents
Warranty
5-year limited warranty (excluding elements)
The HUUM HIVE Flow 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, or chimney-related damage from inadequate maintenance. 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.
