Hearthstone Stoves Green Mountain 80 Freestanding Wood Stove
Cast Iron TruHybrid™ Wood Stove with a Soapstone-Lined Firebox and a 6-Inch Top- or Rear-Exit Flue European cast iron construction with a soapstone-lined 3.15 cubic foot firebox, TruHybrid™ catalytic combustion, a versatile 6-inch flue, and a published HeatLife™ of up to 30 hours. Key Features TruHybrid™ combustion system combining primary and secondary combustion with catalytic tertiary combustion EPA certified at 0.53 g/hr particulate emissions under the 2020 EPA particulate standard, tested with crib wood 80% HHV weighted-average efficiency, measured across four burn-rate categories using EPA Method 28R and CSA B415-10 methodology Published HeatLife™ of up to 30 hours 3.15 cubic foot soapstone-lined firebox accepts logs up to 23" in length Heats up to a maximum of 2,500 square feet, depending on insulation, floor plan, stove placement, and fuel quality 6" flue collar with top or rear exit New-generation Green Mountain styling with an elegant silhouette, linear cast iron texture, and a flush door supported by hidden hinges Large glass window designed to show as much of the fire as possible Approved for U.S. mobile home installation when installed to the manufacturer's requirements Current finish: Black Matte Product Features TruHybrid™ Combustion Technology The TruHybrid™ system burns the fuel, then the gases the wood releases, then routes the remaining exhaust through the catalysts for tertiary combustion. A bypass handle directs combustion products around the catalysts during startup and reloading, and through the catalysts once the catalyst thermometer shows the stove is in its active range. The Green Mountain 80 Model 8681 uses Applied Ceramics ACI-6M2 catalytic combustors, three required, which require periodic inspection and eventual replacement. The catalysts become active around 500°F, and the stove typically operates in the 800°F to 1300°F catalyst temperature range. HearthStone notes that there should be little to no visible smoke from the chimney when the catalysts are in the active zone and fully functional. Cast Iron and Soapstone-Lined Firebox The Green Mountain 80 is built from European cast iron produced at HearthStone's own foundry in Spain, with a soapstone-lined firebox. Soapstone absorbs the heat of the fire and releases it gradually, warming objects in the room rather than only the air. HearthStone notes that soapstone requires gradual break-in fires so the natural moisture in the freshly quarried stone is driven out slowly, and that stone color may change and small surface fractures may appear with use without affecting stove function. New-Generation Green Mountain Styling The Model 8681 carries the new generation of Green Mountain styling, defined by an elegant silhouette, linear cast iron texture, and a flush door supported by hidden hinges. The window into the stove is designed to let you see as much fire as possible from a variety of locations in the room. 6-Inch Flue with Top or Rear Exit The Model 8681 features a 6" flue collar and can be vented through the top or the rear of the stove. To support the firebox, HearthStone focused on the ease of airflow through the stove, supporting quick starting and efficient burning. Minimum chimney height differs by exit: a top-exit installation requires a minimum chimney height of 16 feet off the floor, or 13 feet 5 inches from the top of the stove, while a rear-exit installation requires a minimum of 19 feet off the floor, or 16 feet 5 inches from the top of the stove. The stove requires a draft between 0.06" and 0.1" water column; for drafts above 0.1" WC, HearthStone directs installation of a stovepipe damper. Heating Performance HearthStone publishes a heating area of up to a maximum of 2,500 square feet and a maximum heat output of 80,000 BTU per hour of maple cordwood. Under EPA Method 28 test conditions using Douglas Fir crib wood, the Model 8681 delivered heat at rates ranging from 14,846 to 33,424 BTU (output). HearthStone states in the current owner's manual that the Green Mountain 80 should not be considered the primary heat source for a home, and that factors unique to a given house can reduce the square footage the stove will heat. Everyday Controls A single primary air lever under the ash lip regulates the burn rate, a bypass handle controls catalyst engagement, and a catalyst thermometer shows when the stove is in the active temperature range. The front door is operated by a wood handle, and the primary air control will not close completely, so the minimum allowable airflow is always maintained. Available Finish and Configuration The Green Mountain 80 Model 8681 is currently orderable in one configuration. Finish Part ID MSRP Black Matte 8681-0010 $4,799 Pricing notice: The price shown is the current manufacturer-suggested retail price for the stove. Chimney components, hearth protection, accessories, delivery, installation, and applicable taxes are additional. Specifications Performance Model 8681 Combustion system TruHybrid™ — primary, secondary, and catalytic tertiary combustion Catalytic combustor Applied Ceramics ACI-6M2, three required Heating area Up to a maximum of 2,500 sq ft Maximum heat output 80,000 BTU per hour of maple cordwood Tested heat output range 14,846 to 33,424 BTU (output) under specific test conditions, using Douglas Fir crib wood per the Method 28 loading parameters HeatLife™ Up to 30 hours Typical operating range 800°F to 1300°F catalyst temperature Firebox and Fuel Fuel type Natural cordwood only Firebox capacity 3.15 cu ft Maximum log length Up to 23" (58.4 cm), left to right Certification test log length 19¾" Dimensions and Weight Height 32¾" (83 cm) Width 29½" (75 cm) Depth 25" (63 cm) Weight 550 lbs (250 kg) Crate dimensions H 40" x W 41" x L 31" (102 x 104 x 79 cm) Flue and Installation Flue exit location Top or rear Flue collar and connector size 6" (153 mm) diameter Metal chimney requirement 6" (153 mm) inside diameter, listed Type HT (2100°F) per UL 103 or ULC S629 Masonry chimney requirement Code-approved lined chimney; 6" (153 mm) round flue or 7" x 7" (178 x 178 mm) square flue per the specification table. HearthStone requires a 6" inside diameter flue for new installations and recommends a maximum 6" diameter or 6" x 6" tile size for best results Minimum chimney height, top exit 16 feet (4.9 m) off the floor, or 13 feet 5 inches (4.1 m) from the top of the stove Minimum chimney height, rear exit 19 feet (5.8 m) off the floor, or 16 feet 5 inches (5.0 m) from the top of the stove Recommended maximum chimney height 30 feet (9 m) Required draft 0.06" to 0.1" water column; drafts above 0.1" WC require a stovepipe damper Outside air connection Optional kit 96-53400, minimum 3" (76 mm) diameter duct supplied by others; optional 3" to 4" duct adapter, kit 90-53308 Installation type Freestanding room heater only. Per the current owner's manual, the stove is not to be installed in any factory-built fireplace, or any fireplace Mobile home approval Approved when installed in accordance with 24 CFR Part 3280 and the manufacturer's special mobile home requirements described below Efficiency, Emissions, and Certification HHV efficiency 80% weighted average across four burn-rate categories, measured using EPA Method 28R and CSA B415-10 methodology Particulate emissions 0.53 g/hr EPA certification Certified to comply with the U.S. EPA 2020 particulate emissions standard, tested to EPA Method 28R, 40 CFR Part 60 where applicable, using crib wood Certification report PFS Report F24-314 CO emissions by burn category Category 1 (low) 22.8 g/hr, Category 2 (medium low) 11.7 g/hr, Category 3 (medium high) 1.7 g/hr, Category 4 41.2 g/hr Tested standards Conforms to UL Std. 1482-2022; certified to ULC Std. S627-2023 Clearances and Hearth Requirements The values below are from the current Green Mountain 80 Model 8681 owner's manual, 6400-40100 (revision 5/30/2025). Dimensions are measured from the edge of the top cast iron unless otherwise indicated, with a straight stovepipe directly through the ceiling. Reduced rear clearances require the HearthStone rear heat shield, kit 5968-011. Double-wall connector figures shown by HearthStone are specific to Simpson Dura-Vent DVL and may vary with other brands. Installation Configuration Side — edge of top casting to side wall Rear — edge of top casting to rear wall Connector centerline to rear wall Connector centerline to side wall Corner — edge of top casting to corner wall Corner — connector centerline to corner wall United States — single-wall connector, no rear heat shield 17½" (445 mm) 15½" (394 mm) 21" (534 mm) 32" (813 mm) 7½" (191 mm) 21" (534 mm) United States — single-wall connector with rear heat shield 5968-011 17½" (445 mm) 5½" (140 mm) 11" (280 mm) 32" (813 mm) 7½" (191 mm) 21" (534 mm) United States — double-wall connector, no rear heat shield 17½" (445 mm) 15½" (394 mm) 21" (534 mm) 32" (813 mm) 7½" (191 mm) 21" (534 mm) United States — double-wall connector with rear heat shield 5968-011 17½" (445 mm) 3½" (89 mm) 9" (229 mm) 32" (813 mm) 7½" (191 mm) 21" (534 mm) Canada — single-wall connector with rear heat shield (Canadian requirement) 17½" (445 mm) 15½" (394 mm) 21" (534 mm) 32" (813 mm) 7½" (191 mm) 21" (534 mm) Alcove — single-wall connector, no rear heat shield 17½" (445 mm) 15½" (394 mm) 21" (534 mm) 32" (813 mm) 7½" (191 mm) 21" (534 mm) Alcove — single-wall connector with rear heat shield 5968-011 17½" (445 mm) 5½" (140 mm) 11" (280 mm) 32" (813 mm) 7½" (191 mm) 21" (534 mm) Alcove — double-wall connector, no rear heat shield 17½" (445 mm) 15½" (394 mm) 21" (534 mm) 32" (813 mm) 7½" (191 mm) 21" (534 mm) Alcove — double-wall connector with rear heat shield 5968-011 17½" (445 mm) 5½" (140 mm) 11" (280 mm) 32" (813 mm) 7½" (191 mm) 21" (534 mm) In Canada, single-wall connector installations with the rear heat shield keep the unshielded clearances shown above because of connector pipe minimum-clearance requirements; the reduced U.S. rear values do not apply. The rear heat shield reduces only the rear and connector-to-rear-wall values shown in the manual tables; side and corner clearances are unchanged. The minimum unprotected ceiling height for all vertical-exit installations is 92⅜" (234.6 cm). Alcove, trim, and mantel clearances, unprotected surfaces Measurement Required Dimension Minimum alcove width 64½" (163.8 cm) Minimum alcove ceiling height from floor, single-wall connector 83⅜" (211.7 cm) Minimum alcove ceiling height from floor, double-wall connector 83⅜" (211.7 cm) Alcove side clearance 17½" Unshielded mantel height from floor 68⅜" (173.7 cm) Mantel reference projection, from the front of the stove as shown in the manual figure 28" Pipe centerline to front of stove, reference dimension 15⅞" (403 mm) The 83⅜" alcove ceiling height applies to alcove installations; it is a different requirement from the 92⅜" minimum unprotected ceiling height for vertical-exit installations. Rear-exit installation clearances The values below apply to a through-the-wall flue exit using an elbow directly atop the stove to a rear exit, or using the stove's rear exit. The manual publishes the same values for single-wall and double-wall rear-exit pipe. Installation Configuration Back wall to center of pipe Back wall to edge of pipe Back wall to edge of top casting With rear heat shield 5968-011 — United States 11" (280 mm) 8" (204 mm) 5½" (140 mm) With rear heat shield 5968-011 — Canada 11" (280 mm) 8" (204 mm) 5½" (140 mm) No rear heat shield — United States 21" (534 mm) 18" (458 mm) 15½" (394 mm) No rear heat shield — Canada 21" (534 mm) 18" (458 mm) 15½" (394 mm) Pipe clearances apply to all sides of the connection pipe. Single-wall connector pipe generally requires 18" of clearance, including to the ceiling; for double-wall pipe clearance to the ceiling, refer to the pipe manufacturer's specifications. Use the parallel clearances above for the stove's side-wall requirements in rear-exit installations. Hearth and floor protection Combustible flooring must be protected with a covering of noncombustible material. The Green Mountain 80 does not require an insulated hearth pad and there is no R-value requirement; the requirement is ember protection. The stove is compliant to CAN/ULC-S627 for installation directly over a combustible floor with proper ember protection, and radiant floor insulation protection is not required. Country Minimum Floor Protection United States 38" W x 36½" D Canada 45½" W x 46¼" D Country Measurement Required Extension United States Front extension, from the firebox-door opening 16" United States Side extension, from the firebox opening 8" United States and Canada Hearth edge to chimney connector pipe, rear area 2" (51 mm) Canada Front extension, from the firebox-door opening 18" (457 mm) Canada Side extension, from the side of the stove 8" (203 mm) Canada Rear extension, from the rear of the stove body 8" (203 mm) HearthStone notes that luxury vinyl plank and luxury vinyl tile flooring warrants extra consideration, as some products begin to warp at 110° Fahrenheit, and that additional shielding may be necessary depending on the flooring used. Clearances to combustible surfaces may be reduced using an NFPA 211 approved wall protection system with the additional approval of the regulatory authority having jurisdiction. Mobile and manufactured home installation: The Model 8681 may be installed in a mobile home subject to the manufacturer's special requirements, including installation in accordance with 24 CFR Part 3280 (HUD); use of the outside air kit in all mobile home installations; permanent attachment of the stove to the floor using the shipping clips; a mobile home chimney and connector kit conforming to UL 103 or ULC S629 with a spark arrester secured to the chimney; maintaining the structural integrity of the walls, floor, ceiling, and roof; meeting the chimney height and roof-clearance requirements in the manual; and removal of the chimney when transporting the mobile home. The stove must not be installed in a sleeping room in a mobile home. Installation notice: Clearances and hearth requirements vary by connector type, shielding, and installation configuration. Refer to the current Green Mountain 80 Model 8681 owner's manual and applicable local requirements before installation. Included Equipment Green Mountain 80-1 Model 8681 woodstove Stone Kit A Stone Kit B Owner's manual with installation and operating instructions A separate box beneath the stove contains some of the internal parts, with an instruction sheet for installing them. Compatible Accessories Accessory Part ID MSRP Compatibility or Requirement Note Outside Air Starter 96-53400 $109 Required for all mobile home installations; connects the stove's air intake to a minimum 3" duct, supplied by others. Convection Blower 96-57801 $549 Requires Rear Heat Shield 5968-011, which provides the attachment for the blower. Rear Heat Shield 5968-011 $189 Required for blower installation; also provides the reduced rear-clearance configurations published in the current manual. Does not change side or corner clearances. 3" to 4" Outside Air Increaser 90-53308 $49 For adapting the 3-inch outside-air connection to 4-inch duct where needed. All accessories listed above are optional and sold separately unless expressly stated otherwise. Warranty HearthStone warrants the appliance to the original retail purchaser only, when purchased by that purchaser and installed by an authorized HearthStone dealer or their designated representative, against defects in material or workmanship. Coverage begins on the date of the original invoice and is not transferable to subsequent owners. Warranty periods differ by component. HearthStone defines the term "Limited Lifetime" as 10 years from the beginning of warranty coverage, and applies it to the stone, to cast iron not listed elsewhere, and to the clean-burning air supply system. Door handles and latches and steel components and the firebox carry a 5-year period. Appliance electrical components and refractory, vermiculite panels, and baffles carry a 2-year period. Enamel finish against peeling or fading, glass, accessories, and all components not listed elsewhere carry a 1-year period. The catalytic combustors are covered directly by the combustor manufacturer, Applied Ceramics, under a separate limited warranty that provides free replacement within two years of purchase and prorated replacement pricing thereafter. HearthStone pays for warranty labor performed by an authorized dealer during the first year after the purchase date only when the appliance was installed by an authorized dealer or their designated representative; otherwise, and thereafter, labor is the purchaser's responsibility. Exclusions include over-firing, improper installation or operation, service by anyone other than an authorized dealer, use of unapproved fuels or components, water and corrosion damage, and normal wear parts such as paint, gaskets, baffles, refractory materials, and glass. Surface and hairline cracks and scratches in the stone that do not affect operation or safety are excluded, and HearthStone's obligation does not extend to the appliance's ability to heat a desired space. Warranty registration is not required as a condition of coverage. Refer to the complete warranty in the current Green Mountain 80 Model 8681 owner's manual for the full terms, conditions, and limitations. About HearthStone HearthStone Quality Home Heating Products builds wood- and gas-burning hearth appliances in Morrisville, Vermont, and has been building industry-leading products since 1978. Its stoves are handcrafted by Vermont craftsmen from materials including heating-grade soapstone, cast iron produced at the company's own foundry in Spain, precision-made steel, and engineered ceramics, and every HearthStone soapstone stove is signed by the stove builder. The company's TruHybrid™ system, used across its current wood stove line, adds catalytic tertiary combustion to primary and secondary combustion.