HearthStone Green Mountain 20 TruHybrid Wood Stove

The HearthStone Green Mountain 20 packs cast iron good looks and a soapstone-lined firebox into a compact footprint just 14.7 inches wide. That soapstone soaks up heat from the fire and gives it back gradually. It's finished in Matte Black, and its iron parts are made in HearthStone's own foundry in Spain.

Inside, HearthStone's TruHybrid system combines primary, secondary, and tertiary combustion with a catalytic combustor. HearthStone lists a weighted average efficiency of 78.5% (HHV), and the stove is EPA certified to the 2020 standard at 1.14 grams per hour. The 1.0 cubic foot firebox takes wood up to 18 inches long, and a 6 inch flue exits from the top.

What Makes the Green Mountain 20 Different

• Soapstone-lined firebox. Soapstone absorbs the heat of the fire and releases it gently over time.
• TruHybrid combustion. Primary, secondary, and tertiary combustion work together with a catalytic combustor in HearthStone's TruHybrid design.
• Compact cast iron build. At 14.7 inches wide and 24.9 inches deep, it keeps a small footprint on the hearth.
• Made in HearthStone's foundry. The cast iron parts come from HearthStone's own foundry in Spain.

This listing is the HearthStone Green Mountain 20 TruHybrid wood stove, model 8620, in Matte Black (8620-0010).

Key Specifications

• Firebox volume: 1.0 cu ft
• Maximum log length: 18 in (16 in recommended)
• Flue size: 6 in, top exit
• EPA-tested heat output (manual): 14,545 to 20,507 Btu
• Efficiency (HHV): 78.5% weighted average
• EPA certified emissions: 1.14 g/hr (EPA 2020 standard)
• Combustion: Catalytic (HearthStone TruHybrid)
• Construction: Cast iron with soapstone-lined firebox
• Dimensions (H x W x D): 28 x 14.7 x 24.9 in
• Weight: 250 lb
• Safety listings: UL 1482-2022, CAN/ULC S627:2023

The output range, efficiency, and emissions come from HearthStone's manual and EPA certification. Your results will depend on your home, the chimney, your firewood, and how you run the stove.

Ownership & Maintenance

Like any catalytic stove, the Green Mountain 20's combustor should be inspected from time to time and will eventually need replacing. We offer ongoing service for our customers to help keep it burning clean.

See the Green Mountain 20 and other wood stoves at our Auburn, Brunswick, and Yarmouth showrooms. We'll help you compare models, then work out the chimney, clearances, hearth protection, and installation.