HUUM HIVE Flow LS Wood Burning Sauna Stove
HUUM HIVE Flow LS 9.8 kW through-the-wall wood-burning sauna stove for 282–635 cu ft rooms, fed from the adjacent room, with 330 lb of stones
In stock
Estimated delivery
7–12 days after you order
- HUUM: 75% of the firewood's heat goes into the sauna, not up the chimney
- Firebox passes through the wall, so the fire is lit and fed from the next room
- 330 lb of stones for steam that lasts after the fire is out
- Description
- Specifications
- Installation
- What's Included
- Documents
- Warranty
What is the HUUM HIVE Flow LS wood-burning sauna stove?
The HUUM HIVE Flow LS is a 9.8 kW wood-burning sauna stove from HUUM of Estonia for sauna rooms of 282–635 cu ft. It stands on the floor, holds 330 lb of 2–4" stones (10 boxes of 33 lb) in a metal grate around the stove body, and connects to the chimney at the top or the back. It burns firewood only and needs no electrical connection or controller. The LS version has a firebox 4.7" (120 mm) longer than the HIVE Flow's, built to pass through a non-combustible wall, so the fire is lit and fed from the adjacent room while the stove body and its stones stay in the sauna.
HUUM says 75% of the heat from the firewood goes directly into the sauna rather than escaping up the chimney, and that the large stone mass keeps giving steam for more than 30 minutes after the fire is out. In the Engineering Test Institute's emissions report, the HIVE Flow and HIVE Flow LS reached 74.9% gross efficiency, with particulate emissions of 17 mg/m³. HUUM says its design reduces fire risk, allowing a snug installation. A large glass door shows the fire, and the furnace design is patent pending.
Topture also sells the HIVE Flow LS as a package with stones, protective bedding and a chimney kit included.
Which HUUM HIVE Flow model fits my sauna?
Choose the HIVE Flow by the volume of your sauna room. For every square foot of uninsulated brick, tile or glass wall, add 3.3 cu ft to the room volume before choosing. HUUM's warranty does not cover a stove whose output does not match the room. Each LS version heats the same room range as the model it is based on; its longer firebox passes through a wall so the fire is fed from the next room.
| HIVE Flow | HIVE Flow LS | HIVE Flow Mini | HIVE Flow Mini LS | |
|---|---|---|---|---|
| Heat output | 9.8 kW | 9.8 kW | 8.5 kW | 8.5 kW |
| Sauna room volume | 282–635 cu ft | 282–635 cu ft | 212–494 cu ft | 212–494 cu ft |
| Stones | 330 lb (10 boxes) | 330 lb (10 boxes) | 231 lb (7 boxes) | 231 lb (7 boxes) |
| Weight without stones | 148 lb | 161 lb | 119 lb | 130 lb |
| Width (round body) | 20.7" | 20.7" | 17.7" | 17.7" |
| Depth without door handle | 23.1" | 27.8" | 19.4" | 24.1" |
| Longest firewood | 16" | 16" | 12" | 12" |
| Fire lit and fed from | inside the sauna | the next room, through the wall | inside the sauna | the next room, through the wall |
| HUUM part number | H1015012 | H1016012 | H1017012 | H1018012 |
All four HIVE Flow stoves, and a package for each, are in the HUUM HIVE Flow collection; HUUM's HIVE Wood stoves are with them in the HUUM wood-burning sauna stove collection.
HUUM HIVE Flow LS specifications
| HUUM model and part number | HIVE Flow LS, H1016012 |
|---|---|
| Heat output | 9.8 kW nominal |
| Sauna room volume | 282–635 cu ft (8–18 m³); add 3.3 cu ft per sq ft of uninsulated brick, tile or glass wall |
| Dimensions | 34.8" H × 20.7" W × 27.8" D (884 × 526 × 706 mm); the door handle adds 1.7" (44 mm) to the depth |
| Weight | 161 lb (73 kg) without stones |
| Stones | Needed, not included: 10 boxes × 33 lb = 330 lb (150 kg) of 2–4" HUUM Stones 24, offered with this stove |
| Floor protection under the stove | Required on a wood or other combustible floor; not included. The HUUM LS Protective Bedding L is offered with this stove |
| Floor plate in front of the door | Required on a combustible floor, at least 4" past each side of the door opening and 15 3/4" forward; not included |
| Chimney | Needed, not included: a T450 chimney, connected by a certified installer; HUUM's four chimney kits are offered with this stove |
| Chimney connection on the stove | Top or back; 4.5" (114 mm) chimney leg; the chimney must be temperature class T450 with at least 16 sq in (10,400 mm²) cross-section |
| Through-wall installation | Applies to this model: the firebox, 4.7" (120 mm) longer than the HIVE Flow's, passes through a non-combustible wall up to 4" thick, or 6" with a mounting collar |
| Mounting collar | Optional, not included; needed only in a wall 4–6" thick. The HUUM Mounting Collar L is offered with this stove |
| Stone cage | Optional, not included; the HUUM Cage HSTV is offered with this stove |
| Electrical connection | None needed; wood-fired, no controller |
| Fuel | Firewood only, hardwood or softwood, 10–15% moisture |
| Firewood length | 12" recommended, 16" maximum |
| Flue gas temperature | 642°F average and 725°F maximum at nominal output |
| Efficiency and emissions | 74.9% gross efficiency; CO 346 mg/m³ and particulates 17 mg/m³ at 13% O₂ (emissions report, Engineering Test Institute, Brno) |
| Emission standards | Certified to EN 15821 under the EU Construction Products Regulation (certificate CPR-B-00659-24); meets Germany's 1. BImSchV Stage 2, per the emissions report of the Engineering Test Institute, Brno |
| Sauna room height | 75" (1,900 mm) minimum; 79–91" recommended |
| Made in | Estonia; furnace design patent pending |
| Warranty | 3 years private use, 1 year commercial use (HUUM); the door glass, ash grate and stones are excluded |
How is the HUUM HIVE Flow LS installed?
The HIVE Flow LS stands on a non-combustible floor strong enough to carry it and its 330 lb of stones; HUUM names a concrete floor at least 2" (50 mm) thick as suitable. On wood or another combustible floor, HUUM's manual makes a non-combustible base mandatory, such as HUUM's LS Protective Bedding L, with a ventilation gap of at least 1 3/16" (30 mm) under it, and it is also recommended over underfloor heating pipes. A sheet-metal plate must cover the combustible floor in front of the stove, reaching at least 4" (100 mm) past each side of the door opening and 15 3/4" (400 mm) forward, with the edge nearest the stove bent up so coals cannot slide under it.
Installing the HIVE Flow LS through a wall
The HIVE Flow LS's firebox passes through a non-combustible wall (stone or concrete, for example), so the stove body and its stones sit in the sauna while the fire door opens into the adjacent room. HUUM's manual allows a wall up to 4" (100 mm) thick, or up to 6" (150 mm) with the Mounting Collar L, keeps at least 2" (50 mm) between the stove and the wall, and requires that no combustible wall material protrudes into the opening.
| Non-combustible wall, at least (W × H) | Wall opening, at least (W × H) | |
|---|---|---|
| Stove on the floor, no collar | 26 × 41 in (650 × 1,050 mm) | 13 × 19 in (320 × 470 mm) |
| Stove on the floor, with the HUUM mounting collar | 26 × 41 in (650 × 1,050 mm) | 19 × 22 in (485 × 560 mm) |
| Stove on HUUM protective bedding, with the collar | 26 × 43 in (650 × 1,100 mm) | 19 × 24 in (485 × 615 mm) |
HUUM HIVE Flow LS safety distances
Keep at least these distances from the HIVE Flow LS to walls, benches and anything that can burn. The letters match HUUM's drawing.
| A: sides and back | 6" (150 mm) |
|---|---|
| B: in front of the door | 20" (500 mm) |
| C: total side-to-side span (A + stove + A) | 33" (826 mm) |
| Above the stove | 40" (1,000 mm) |
| To a non-combustible wall | 2" (50 mm) |
A non-combustible protective screen cuts the side distances by 50% (single screen) or up to 75% (double screen), and the distance to the ceiling by 25% (single screen only); the distance is still measured to the combustible surface. HUUM asks you to check local safety rules before reducing any distance. The sauna room must be at least 75" tall; HUUM recommends 79–91", with 44–51" from the top bench to the ceiling.
Connecting the HIVE Flow LS to a chimney
Only a certified installation expert may connect the HIVE Flow LS to the chimney. HUUM's manual calls for a chimney of temperature class T450 with a cross-section of at least 16 sq in (10,400 mm²), joined to the stove's 4.5" (114 mm) chimney leg at the top or the back. For a back connection the bolted chimney leg and its cover plate swap places, and two ribs of the stone grate are cut and fixed with the two metal fixing plates in the box. Seal the joints with heat-resistant rope or stone wool. Because the flue gas stays below 752°F (400°C), HUUM allows the stove to share an existing flue that already serves a fireplace, if your local authority and fire department agree.
| Connects at | Route out of the sauna | |
|---|---|---|
| Thru-Wall | Top | Rises from the top of the stove, turns 90° through the wall and runs up the outside of the building |
| Thru-Flat or Curved Ceiling | Top | Goes straight up through a flat or curved (barrel) ceiling and roof |
| Thru-Angled Ceiling | Top | Goes up through the ceiling and out through a roof pitched 0–20° |
| Thru-Wall Backside Connection | Back | Leaves the back of the stove straight through the wall, then runs up the outside of the building |
HUUM's manual asks for fresh supply air directed as close to the HIVE Flow LS as possible, and warns that forced (mechanical) ventilation can starve the fire of combustion air, so check the ventilation design before the first sauna. It also advises checking local fire safety rules before installing a wood-burning stove.
Before the first fire: HUUM's outdoor burn-in
HUUM's manual requires the HIVE Flow LS to be fired outdoors at least once before it is installed, because the protective paint on the stove body gives off unpleasant fumes while it cures. Remove the stone grate, lay no stones, fit the ash grate, ash drawer and cleaning hatches, and burn one or two loads of firewood in a sheltered, well-ventilated spot with the door slightly open, never closed, until no smoke or steam comes off the surface. Do not throw water on the stove. A length of flue pipe on the chimney leg improves the draft.
Lighting the HIVE Flow LS and adding wood
Burn firewood only, hardwood or softwood at 10–15% moisture, in logs of about 12" (30 cm), no longer than 16" (40 cm), weighing 0.8–1.5 lb each. Lay thin wood at the bottom, the thickest in the middle and kindling on top, then light it from the top. Keep the ash drawer open (its limiter allows 1/8") for no more than 15 minutes, then close it for the rest of the heating. Add wood only once the previous load has burned down to glowing coals, filling the firebox to no more than two thirds of its height. HUUM's maximum loads for the HIVE Flow LS are 11 lb (5 kg) to start, then 5 lb (2.2 kg) and 4 lb (1.8 kg), and no more than 9 lb (4 kg) per hour. If the stove surface glows red it is overheating: close the air valve under the door at once.
Stones, steam and yearly care
Wash the 330 lb of stones, check that the cleaning hatches are in place, then lay the stones evenly, layer by layer, level with the top of the grate, without forcing any between the grate and the stove body. Make steam only once the stones are fully hot: about 1/3 cup (80 ml) of water at a time, never salt or chlorinated water. HUUM says the stones keep giving steam for more than 30 minutes after the fire is out. Have a chimney sweep clean the chimney, the flue connections and the stove's own flues at least once a year, check the stones yearly, and expect to renew them about every two years. Check the door seal each time you clean the glass, and never heat the stove with cracked glass.
What's in the box with the HUUM HIVE Flow LS?
- The sauna stove
- Metal stone grate
- Ash grate
- Ash drawer
- Cleaning hatches (2)
- Metal fixing plates (2), used for a back chimney connection
- Splints
- Heat-resistant glove
- Installation and operation manual
What you need separately
- 10 boxes (330 lb) of HUUM Stones 24, rounded 2–4" stones
- A chimney connected by a certified installer: one of the HUUM chimney kits (HUUM Thru-Wall Chimney Kit, HUUM Thru-Flat or Curved Ceiling Chimney Kit, HUUM Thru-Angled Ceiling Chimney Kit, HUUM Thru-Wall Backside Connection Chimney Kit) or another T450 chimney approved locally
- On a combustible floor: the LS Protective Bedding L or another non-combustible base, plus a sheet-metal plate in front of the door
- A non-combustible wall for the firebox to pass through; the Mounting Collar L is optional
- Optional: the HUUM stone cage (Cage HSTV), which HUUM lists for every HIVE Flow model
HUUM warranty periods
HUUM's limited warranty (Limited Warranty Terms and Conditions, US, v2) covers new HUUM products bought from HUUM or its authorized dealers, such as Topture, against defects in materials and workmanship. The period starts on the date the end user buys the product.
| HUUM product | Private use | Commercial use |
|---|---|---|
| Electric sauna heaters | 3 years | 1 year |
| Wood-burning sauna stoves | 3 years | 1 year |
| Control units (UKU) | 3 years | 1 year |
| Spare parts | 1 year | 1 year |
HUUM counts as commercial use a business using the product commercially, a private owner using it commercially, or a private owner using it for more than 1,500 hours in 12 months.
What the warranty does not cover
- Heating elements of electric heaters
- HUUM accessories, such as rails, reflectors, flanges, protective bedding and chimney parts
- Door glass and ash grate of wood-burning stoves
- Sauna stones
- All controller sensors
- Damage from a heater that is the wrong size for the room, from unsuitable stones, or from installation, use or maintenance that does not follow HUUM's manuals
What keeps the warranty in effect
- Inspect the product when it arrives and report any visible damage within 7 days, with photos, before installing it.
- Install it following HUUM's manual and local building, electrical and fire codes. An electric product must be connected by a licensed electrician, with proof of the installation.
- Report a defect within 30 days of finding it. For products bought from Topture, report it to Topture, which passes the claim to HUUM and helps with troubleshooting.
