Features
TruHybrid™ System
Our TruHybrid™ system burns so cleanly and efficiently, your chimney smoke is barely visible.
Soapstone Comfort
Enjoy long-lasting comfortable heat thanks to the soapstone-lined firebox. Soapstone absorbs the heat of the fire for hours of cozy comfort.
Clean-lined Cast Iron
More than just a black box, the GM20 is designed in cast iron with a clean, modern style that compliments both traditional and contemporary homes.
25C Tax Credit information for products purchased and installed on or before 12/31/2025 >>
Efficiency
78.5%
HeatLife
9.5
EPA Certified
1.14
g/hr
Specifications
BTU: Up to 23,000
Efficiency: 78.5%
EPA Certified: 1.14 g/hr
Finish: Matte Black
Firebox Capacity: 1.0 cubic feet
Flue Exit Diameter: 6″
Flue Exit Location: Top
HeatLife: 9.5
Heats up to: 575 sq. ft.
Maximum Log Length: 18″ (16″ recommended)
Model: 8620
Stove Type: Cast Iron Wood Stove
Weight: 285
Accessories
Rear Heat Shield: 96-68200
Side Heat Shield: 96-68205
Outside Air Stater Kit, 3″: 96-53400
Outside Air Increaser, 3″ to 4″: 90-53308
Clearances
- Side: 13.75″
- Rear: 10″ (15.25″ CAN)
- Corner: 9.5″ (12.5″ CAN)
Single-wall connector pipe, no heat shields - Side: 13.75″
- Rear: 9″
- Corner: 9.5″
Double-wall connector pipe, no heat shields
- Side: 9″
- Rear: 3.5″
- Corner: 4″
Double-wall connector pipe with side & rear heat shields
TruHybrid™
Combustion Technology
Our TruHybrid™ system combines primary, secondary, and tertiary combustion to deliver exceptional performance.
The clean combustion is visible. Thanks to the TruHybrid™ technology, a roaring fire won’t produce any visible smoke from the chimney.
Learn More About TruHybrid
Our Materials
Each HearthStone is handcrafted using a combination of precision-made components in cast iron, soapstone, steel, ceramic, and various other materials. Our commitment to quality and attention to detail ensures that your product will serve you faithfully for years to come.
Soapstone
Soapstone is a natural material that absorbs the high heat of a fire, then radiates a gentle heat into the room. Soapstone warms the objects in your home, not just the air, resulting in a comfortable, livable heat.
Learn more about heating with soapstone
Cast Iron
Using selected raw and recycled material, our iron parts are produced in our foundry in Spain. Our modern casting facility guarantees durable, reliable, high-quality cast iron parts.
Configuration
& Options
Rear Heat Shield: 96-68200
Side Heat Shield: 96-68205
Outside Air Stater Kit, 3″: 96-53400
Outside Air Increaser, 3″ to 4″: 90-53308
Accessories
Heat Shields, Green Mountain 20
Rear Heat Shield 96-68200
Side Heat Shield 96-68205
The rear heat shield clips onto the back of the stove. The side heat shield clips onto either the left side, right side, or both sides of the stove. Heat shields can be installed individually to reduce the required distance between the stove and the wall being shielded.
Outside Air Starter Kit, 3″
96-53400
Bring air into your stove from outside of your house to ensure proper combustion and keep more heat in your home. Recommended for newer well-sealed homes. 3″ ducting not included.
Outside Air Increaser, 3″ to 4″
90-53308
Use the increaser for longer outside air pipes to make sure enough fresh air is reaching your stove.
