A Compact Soapstone Wood Stove with TruHybrid™ Catalytic Combustion and Extra Long Burn Times
Soapstone and cast iron construction, TruHybrid™ catalytic combustion, a square 19" wide by 17" deep firebox, and published burn times of up to 20+ hours.
Key Features
- TruHybrid™ combustion system combining primary and secondary combustion with catalytic tertiary combustion
- EPA certified at 0.98 g/hr particulate emissions under the 2020 EPA particulate standard, tested with crib wood
- 77.3% HHV weighted-average efficiency, measured across four burn-rate categories using EPA Method 28R and CSA B415-10 methodology
- Published burn time of up to 20+ hours, depending on wood, draft, and operating conditions
- Soapstone and cast iron construction, with cast iron produced at HearthStone's own foundry in Spain
- Square 19" wide by 17" deep firebox accepts logs up to 18" in length
- Heats up to a maximum of 1,500 square feet, depending on insulation, floor plan, stove placement, and fuel quality
- Three current finishes: Matte Black, Brown Enamel, and Seafoam Enamel
- 6" flue collar with top or rear exit, and approval for U.S. mobile home installation when installed to the manufacturer's requirements
Product Features
TruHybrid™ Combustion Technology
The TruHybrid™ system burns the fuel, then the gases the wood releases, then routes the remaining exhaust through the catalyst for tertiary combustion. HearthStone describes a 4-tube secondary combustion system with a fixed baffle that ensures a clean burn before the catalyst performs the finishing touches. A bypass handle directs combustion products around the catalyst during startup and reloading, and through the catalyst once the catalyst probe shows the stove is in its active range. The Castleton uses Applied Ceramics ACI-6M2 catalytic combustors, which require periodic inspection and eventual replacement. The catalyst becomes active around 500°F, and the Castleton 8031 typically operates in the 800°F to 1300°F range.
Soapstone and Cast Iron Construction
The Castleton combines soapstone with cast iron elements produced at HearthStone's own foundry. 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.
Convenient Square Firebox
The square shape of the Castleton creates a 19" wide by 17" deep firebox suited to loading and arranging firewood. HearthStone publishes a firebox capacity of 1.9 cubic feet in the current owner's manual, and the firebox accepts logs up to 18" in length.
Fire Viewing and Everyday Operation
A large glass window lets the fire be seen from a variety of locations in the room. A single primary air control lever below the ash lip regulates the burn rate and does not close completely, the bypass handle controls catalyst engagement, and a catalyst probe shows when the stove is in the active temperature range. Turn the stove to high and stoke a big fire, or turn it all the way down to keep a fire burning overnight.
Heating Performance
HearthStone publishes a heating area of up to a maximum of 1,500 square feet and a maximum heat output of 45,000 BTU per hour of cordwood, based on independent laboratory test results. Under EPA test conditions, the Castleton 8031 delivered heat at rates ranging from 12,501 to 24,540 BTU (output). HearthStone states in the current owner's manual that the Castleton 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.
Available Finishes and Configurations
The Castleton 8031 is currently orderable in three finishes. Pricing varies by finish.
| Finish |
Part ID |
MSRP |
| Black Matte |
8031-4110 |
$4,049 |
| Brown Enamel |
8031-4120 |
$4,749 |
| Seafoam Enamel |
8031-4161 |
$4,749 |
Pricing notice: Prices shown are current manufacturer-suggested retail prices for the stove in the selected finish. Chimney components, hearth protection, accessories, delivery, installation, and applicable taxes are additional.
Specifications
Performance
| Model |
8031 |
| Combustion system |
TruHybrid™ — primary, secondary, and catalytic tertiary combustion |
| Catalytic combustor |
Applied Ceramics ACI-6M2 |
| Heating area |
Up to a maximum of 1,500 sq ft |
| Maximum heat output |
45,000 BTU per hour of cordwood, based on independent laboratory test results |
| Tested heat output range |
12,501 to 24,540 BTU (output) under specific test conditions |
| Burn time |
Up to 20+ hours |
| HeatLife™ |
Up to 24 hours, per the current owner's manual (revision 01/11/23) |
| Typical operating range |
800°F to 1300°F catalyst temperature; catalyst becomes active around 500°F |
Firebox and Fuel
| Fuel type |
Natural cordwood only |
| Firebox capacity |
1.9 cu ft |
| Firebox size |
19" wide x 17" deep |
| Maximum log length |
Up to 18" (45.7 cm) |
| Ash pan |
Not offered for this model |
Dimensions and Weight
| Height |
27½" (69.8 cm) |
| Width |
25½" (64.7 cm) |
| Depth |
21⅞" (55.5 cm) |
| Weight |
520 lbs (235 kg) |
| Crate dimensions |
H 39" x W 29" x L 36" (99 x 73.7 x 91.5 cm), add 4" (10.2 cm) for pallet |
Flue and Installation
| Flue exit location |
Top or rear; rear exit requires the top-to-rear venting conversion described in the owner's manual |
| Flue collar and connector size |
6" (152 mm) diameter; single-wall connector must be at least 24 MSG or 25 MSG blued steel stovepipe |
| Metal chimney requirement |
6" (152 mm) inside diameter, listed Type HT (2100°F) per UL 103 or ULC S629 |
| Masonry chimney requirement |
Code-approved lined chimney; maximum 6" (152 mm) diameter round flue or 8" x 8" (203 x 203 mm) tile for best results |
| Recommended minimum chimney height, top exit |
16 feet (4.9 m) off the floor, or 13 feet 10⅛" (4.3 m) from the top of the stove |
| Recommended minimum chimney height, rear exit |
19 feet (5.8 m) off the floor, or 16 feet 10⅛" (5.2 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, verified at installation |
| Outside air connection |
Optional kit 90-53300, minimum 3" (76 mm) diameter duct supplied by others |
| Mobile home approval |
Approved in the U.S. when installed per 24 CFR Part 3280; outside air kit, permanent floor attachment using the supplied shipping clips, and a listed mobile home chimney and connector kit with a stainless spark arrester cap are required; not for installation in a sleeping room |
| Factory-built fireplaces |
The Castleton is to be installed as a freestanding room heater and is not to be installed in any factory-built fireplace |
Efficiency, Emissions, and Certification
| HHV efficiency |
77.3% weighted average across four burn-rate categories, measured using EPA Method 28R and CSA B415-10 methodology |
| Particulate emissions |
0.98 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 file |
PFS File F17-182 |
| CO emissions by burn category |
Category 1 (low) 0.56 g/min, Category 2 (medium low) 0.43 g/min, Category 3 (medium high) 0.59 g/min, Category 4 0.67 g/min |
| Tested standards |
Conforms to UL Std. 1482-2022; certified to ULC Std. S627-2021 |
Clearances and Hearth Requirements
The values below are from the current Castleton 8031 owner's and installation manual (revision 01/11/23). Reduced rear clearances require the HearthStone rear heat shield, kit 90-68300. Close-clearance connector pipe must be listed; double-wall figures shown by HearthStone are specific to Simpson Dura-Vent DVL and may vary with other brands. Dimensions are measured from the top casting of the stove unless otherwise indicated.
The manual's clearance figure (Figure 4) defines the measurements as follows: A is the stove side to the side wall, B is the stove rear to the rear wall, C is the chimney connector to the rear wall, D is the chimney connector to the side wall, E is the stove body to the corner wall, and F is the chimney connector to the corner wall.
| Connector Configuration |
A — Side Wall |
B — Rear Wall |
C — Connector to Rear Wall |
D — Connector to Side Wall |
E — Corner Wall |
F — Connector to Corner Wall |
| Single-wall connector, no rear heat shield |
17" (44 cm) |
15" (39 cm) |
20" (51 cm) |
29.25" (75 cm) |
8" (21 cm) |
20.5" (53 cm) |
| Single-wall connector, with rear heat shield 90-68300 |
17" (44 cm) |
9" (23 cm) |
14" (36 cm) |
29.25" (75 cm) |
8" (21 cm) |
20.5" (53 cm) |
| Double-wall connector, no rear heat shield |
17" (44 cm) |
15" (39 cm) |
20" (51 cm) |
29.25" (75 cm) |
8" (21 cm) |
20.5" (53 cm) |
| Double-wall connector, with rear heat shield 90-68300 |
17" (44 cm) |
8" (21 cm) |
13" (33 cm) |
29.25" (75 cm) |
8" (21 cm) |
20.5" (53 cm) |
| Alcove installation, single- or double-wall connector, with or without rear heat shield |
17" (44 cm) |
16" (41 cm) |
21" (54 cm) |
29.25" (75 cm) |
8" (21 cm) |
20.5" (53 cm) |
Chimney connector clearances
The manual publishes the following chimney connector clearances for through-the-wall top flue or direct rear exit installations (Figure 5).
| Connector Configuration |
Stove or Direct-Rear-Exit Area to Rear Wall |
Vertical Chimney Connector to Rear Wall |
| Single-wall pipe with rear heat shield 90-68300 |
11" (27.94 cm) |
16" (40.6 cm) |
| Single-wall pipe without rear heat shield |
17" (43.2 cm) |
22" (55.9 cm) |
| Double-wall pipe with rear heat shield 90-68300 |
10" (25.4 cm) |
15" (38.1 cm) |
| Double-wall pipe without rear heat shield |
17" (43.2 cm) |
22" (55.9 cm) |
| Connector Type |
Clearance to Ceiling |
| Single-wall pipe, unprotected ceiling |
18" (46 cm) |
| Single-wall pipe, protected ceiling |
9" (23 cm) |
| Double-wall pipe |
Refer to the connector manufacturer's specifications |
Trim and mantel clearances
The values below are from the trim and mantel clearance figure (Figure 6) of the current manual, which shows a trim thickness of 1.25".
| Measurement |
Required Clearance |
| Side trim clearance |
10" |
| Top trim clearance above stove |
24" |
| Mantel height above floor |
60" |
Alcove installation, unprotected surfaces
| Installation Configuration |
Measurement |
Required Dimension |
| Alcove, unprotected surfaces |
Minimum alcove width |
59" (149.9 cm) |
| Alcove, unprotected surfaces |
Maximum alcove depth |
52" (132.0 cm) |
| Alcove, unprotected surfaces |
Minimum alcove ceiling height from floor, single- or double-wall connector |
60" (152.4 cm) |
Hearth and floor protection
Combustible flooring must be protected with a covering of noncombustible material. The Castleton 8031 does not require an insulated hearth pad and there is no R-value requirement; the requirement is ember protection.
| Country |
Minimum Floor Protection |
| United States |
37" x 31½" |
| Canada |
47" x 41" |
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.
Installation notice: Clearances and hearth requirements vary by connector type, shielding, and installation configuration. Refer to the current Castleton 8031 installation manual and applicable local requirements before installation.
Included Equipment
- Castleton Model 8031 woodstove with catalytic combustors installed and secured for shipping
- Owner's manual with installation and operating instructions
- Wood handles with screws and washers
- Canadian Handle Kit 90-71310, supplied where applicable for Canadian installations
Compatible Accessories
| Accessory |
Part ID |
MSRP |
Compatibility or Requirement Note |
| Outside Air Starter |
90-53300 |
$199 |
For the Castleton. Required for mobile home installations. Connects to a minimum 3" duct supplied by others; ducting is not included. |
| Blower |
90-57210 |
$599 |
For Mansfield, Heritage, and Castleton. Requires the rear heat shield, which provides attachment for the blower. |
| Rear Heatshield |
90-68300 |
$149 |
For the Castleton. Required for reduced rear clearances and for blower installation. |
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 carry a 2-year period. Enamel finish against peeling or fading, glass, the ash grate, 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, ash grates, 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 Castleton 8031 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.
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